Hardening Microsoft
Windows 10 version 1709
Workstations
Table of Contents
Introduction
6
High priorities
7
Application hardening
7
Application versions and patches
7
Application whitelisting
7
Attack Surface Reduction
10
Credential caching
11
Controlled Folder Access
12
Credential entry
13
Early Launch Antimalware
13
Elevating privileges
14
Exploit Protection
15
Local administrator accounts
16
Measured Boot
16
Microsoft Edge
17
Multi-factor authentication
18
Operating system architecture
18
Operating system patching
18
Operating system version
19
Password policy
20
Restricting privileged accounts
20
Secure Boot
21
Medium priorities
22
2
Account lockout policy
22
Anonymous connections
22
Antivirus software
23
Attachment Manager
25
Audit event management
25
Autoplay and AutoRun
28
BIOS and UEFI passwords
28
Boot devices
28
Bridging networks
28
Built-in guest accounts
29
Case locks
29
CD burner access
29
Centralised audit event logging
30
Command Prompt
30
Direct Memory Access
30
Endpoint device control
31
File and print sharing
32
Group Policy processing
32
Hard drive encryption
33
Installing applications
36
Internet printing
37
Legacy and run once lists
38
Microsoft accounts
38
MSS settings
39
NetBIOS over TCP/IP
39
Network authentication
39
3
NoLMHash policy
40
Operating system functionality
40
Power management
40
PowerShell
42
Registry editing tools
42
Remote Assistance
42
Remote Desktop Services
43
Remote Procedure Call
45
Reporting system information
45
Safe Mode
46
Secure channel communications
46
Security policies
47
Server Message Block sessions
48
Session locking
49
Software-based firewalls
50
Sound Recorder
51
Standard Operating Environment
51
System backup and restore
51
System cryptography
52
User rights policies
52
Virtualised web and email access
53
Web Proxy Auto Discovery protocol
53
Windows Remote Management
54
Windows Remote Shell access
54
Windows Search and Cortana
55
Windows To Go
55
4
Low priorities
56
Displaying file extensions
56
File and folder security properties
56
Location awareness
56
Microsoft Store
57
Publishing information to the Web
57
Resultant Set of Policy reporting
58
Contact details
59
5
Introduction
Workstations are often targeted by an adversary using malicious webpages, emails with malicious attachments and
removable media with malicious content in an attempt to extract sensitive information. Hardening workstations is an
important part of reducing this risk.
This document provides guidance on hardening workstations using Enterprise and Education editions of Microsoft
Windows 10 version 1709. Some Group Policy settings used in this document may not be available or compatible with
Professional, Home or S editions of Microsoft Windows 10 version 1709.
While this document refers to workstations, most Group Policy settings are equally applicable to servers (with the
exception of Domain Controllers) using Microsoft Windows Server, version 1709 or Microsoft Windows Server 2016.
The names and locations of Group Policy settings used in this document are taken from Microsoft Windows 10 version
1709; some differences exist for earlier versions of Microsoft Windows.
Before implementing recommendations in this document, thorough testing should be undertaken to ensure the
potential for unintended negative impacts on business processes is reduced as much as possible.
This document is intended for information technology and information security professionals within organisations
looking to undertake risk assessments or vulnerability assessments as well as those wishing to develop a hardened
Standard Operating Environment for workstations.
6
High priorities
The following security controls, listed in alphabetical order, are considered to have an excellent effectiveness and
should be treated as high priorities when hardening Microsoft Windows 10 version 1709 workstations.
Application hardening
When applications are installed they are often not pre-configured in a secure state. By default, many applications
enable functionality that isn’t required by any users while in-built security functionality may be disabled or set at a
lower security level. For example, Microsoft Office by default allows untrusted macros in Office documents to
automatically execute without user interaction. To reduce this risk, applications should have any in-built security
functionality enabled and appropriately configured along with unrequired functionality disabled. This is especially
important for key applications such as office productivity suites (e.g. Microsoft Office), PDF readers (e.g. Adobe
Reader), web browsers (e.g. Microsoft Internet Explorer, Mozilla Firefox or Google Chrome), common web browser
plugins (e.g. Adobe Flash), email clients (Microsoft Outlook) and software platforms (e.g. Oracle Java Platform and
Microsoft .NET Framework). In addition, vendors may provide guidance on configuring their products securely. For
example, Microsoft provides security baselines for their products on their Microsoft Security Guidance blog 1. In such
cases, vendor guidance should be followed to assist in securely configuring their products.
The Australian Cyber Security Centre (ACSC) also provides guidance for hardening Microsoft Office. For more
information see the Hardening Microsoft Office 2013 and Hardening Microsoft Office 365 ProPlus, Office 2019
and Office 2016 publications2 3.
Application versions and patches
While some vendors may release new application versions to address security vulnerabilities, others may release
patches. If new application versions and patches for applications are not installed it can allow an adversary to easily
compromise workstations. This is especially important for key applications that interact with content from untrusted
sources such as office productivity suites (e.g. Microsoft Office), PDF readers (e.g. Adobe Reader), web browsers (e.g.
Microsoft Internet Explorer, Mozilla Firefox or Google Chrome), common web browser plugins (e.g. Adobe Flash), email
clients (Microsoft Outlook) and software platforms (e.g. Oracle Java Platform and Microsoft .NET Framework). To
reduce this risk, new application versions and patches for applications should be applied in an appropriate timeframe as
determined by the severity of security vulnerabilities they address and any mitigating measures already in place. In
cases where a previous version of an application continues to receive support in the form of patches it still should be
upgraded to the latest version to receive the benefit of any new security functionality; however, this may be done as
soon as practical rather than within two days of release.
For more information on determining the severity of security vulnerabilities and timeframes for applying new
application versions and patches for applications see the Assessing Security Vulnerabilities and Applying Patches
publication4.
Application whitelisting
An adversary can email malicious code, or host malicious code on a compromised website, and use social engineering
techniques to convince users into executing it on their workstation. Such malicious code often aims to exploit security
vulnerabilities in existing applications and doesn’t need to be installed on the workstation to be successful. To reduce
1
https://blogs.technet.microsoft.com/secguide/
https://www.acsc.gov.au/publications/protect/Hardening_MS_Office_2013.pdf
3
https://www.acsc.gov.au/publications/protect/Hardening_MS_Office_2016.pdf
4
https://www.acsc.gov.au/publications/protect/Assessing_Security_Vulnerabilities_and_Applying_Patches.pdf
2
7
this risk, an application whitelisting solution should be appropriately implemented. Application whitelisting when
implemented in its most effective form (e.g. using hashes for executables, dynamic link libraries, scripts, installers and
packaged apps) can be an extremely effective mechanism in not only preventing malicious code from executing but also
ensuring only authorised applications can be installed on workstations. Less effective implementations of application
whitelisting (e.g. using approved paths for installed applications in combination with access controls requiring
privileged access to write to these locations) can be used as a first step towards implementing a more comprehensive
application whitelisting solution.
For more information on application whitelisting and how it can be appropriately implemented see the Implementing
Application Whitelisting publication5.
If Microsoft AppLocker6 is used for application whitelisting, the following rules can be used as a sample path-based
implementation. In support of this, the rules, enforcement of rules and the automatic starting of the Application
Identity service should be set via Group Policy at a domain level.
Whitelisting Rule
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Application Control Policies\AppLocker\
DLL Rules
[Path] %ProgramFiles%\*
Allow Everyone
[Path] %WinDir%\*
Allow Everyone
Exceptions:
%System32%\spool\drivers\color\*
%System32%\Tasks\*
%WinDir%\Tasks\*
%WinDir%\Temp\*
Computer Configuration\Policies\Windows Settings\Security Settings\Application Control Policies\AppLocker\
Executable Rules
[Path] %ProgramFiles%\*
Allow Everyone
[Path] %WinDir%\*
Allow Everyone
Exceptions:
%System32%\spool\drivers\color\*
%System32%\Tasks\*
%WinDir%\Tasks\*
%WinDir%\Temp\*
Computer Configuration\Policies\Windows Settings\Security Settings\Application Control Policies\AppLocker\
Packaged app Rules
5
https://www.acsc.gov.au/publications/protect/Application_Whitelisting.pdf
https://docs.microsoft.com/en-au/windows/security/threat-protection/windows-defender-applicationcontrol/applocker/applocker-overview
6
8
[Publisher] CN=Microsoft Corporation, O=Microsoft
Corporation, L-Redmond, S=Washington, C=US
Allow Everyone
Computer Configuration\Policies\Windows Settings\Security Settings\Application Control Policies\AppLocker\
Script Rules
[Path] %ProgramFiles%\*
Allow Everyone
[Path] %WinDir%\*
Allow Everyone
Exceptions:
%System32%\Com\dmp\*
%System32%\FxsTmp\*
%System32%\spool\drivers\color\*
%System32%\spool\PRINTERS\*
%System32%\spool\SERVERS\*
%System32%\Tasks\*
%WinDir%\Registration\CRMLog\*
%WinDir%\Tasks\*
%WinDir%\Temp\*
%WinDir%\tracing\*
Computer Configuration\Policies\Windows Settings\Security Settings\Application Control Policies\AppLocker\
Windows Installer Rules
[Publisher] CN=Microsoft Corporation, O=Microsoft
Corporation, L-Redmond, S=Washington, C=US
Allow Everyone
Note, for those organisations using the latest version of Microsoft Windows 10 (i.e. version 1709), the following paths
no longer need to be included as exceptions:
%WinDir%\servicing\Packages\*
%WinDir%\servicing\Sessions\*.
A security feature in Microsoft Windows 10 version 1709 is Device Guard7 8. Device Guard uses a Code Integrity Policy
to restrict what can run in both kernel mode and on the desktop based on its policy. Device Guard also uses
virtualisation to protect itself from being disabled by an adversary that has obtained administrative privileges.
However, while Device Guard can implement application whitelisting, organisations are likely to require an additional
application whitelisting solution to supplement Device Guard, especially if choosing to use a path-based approach for
application whitelisting.
If Device Guard is used for application whitelisting, the following Group Policy settings can be implemented, assuming
all software, firmware and hardware pre-requests are met.
7
https://docs.microsoft.com/en-au/windows/security/threat-protection/device-guard/introduction-to-device-guardvirtualization-based-security-and-windows-defender-application-control
8
https://docs.microsoft.com/en-au/windows/security/threat-protection/windows-defender-applicationcontrol/windows-defender-application-control-deployment-guide
9
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Device Guard
Deploy Windows Defender Application Control
Enabled
Code Integrity Policy file path: <organisation defined>
Turn On Virtualization Based Security
Enabled
Virtualization Based Protection of Code Integrity:
Enabled with UEFI lock
Attack Surface Reduction
Attack Surface Reduction (ASR)9 is a security feature in Microsoft Windows 10 version 1709 that forms part of Windows
Defender Exploit Guard. It is designed to combat the threat of malware exploiting legitimate functionality in Microsoft
Office applications. In order to use ASR, Windows Defender Antivirus must be configured as the primary real-time
antivirus scanning engine on workstations.
ASR offers a number of attack surface reduction rules, these include:
block executable content from email client and webmail:
BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550
block Office applications from creating child processes:
D4F940AB-401B-4EFC-AADC-AD5F3C50688A
block Office applications from creating executable content:
3B576869-A4EC-4529-8536-B80A7769E899
block Office applications from injecting code into other processes:
75668C1F-73B5-4CF0-BB93-3ECF5CB7CC84
block JavaScript and VBScript from launching downloaded executable content:
D3E037E1-3EB8-44C8-A917-57927947596D
block execution of potentially obfuscated scripts:
5BEB7EFE-FD9A-4556-801D-275E5FFC04CC
block Win32 API calls from Office macro:
92E97FA1-2EDF-4476-BDD6-9DD0B4DDDC7B.
Organisations should either implement ASR using Windows Defender Antivirus or use third party antivirus solutions
that offer similar functionality to those provided by ASR. For older versions of Microsoft Windows, alternative measures
will need to be implemented to mitigate certain threats addressed by ASR, such as the likes of Dynamic Data Exchange
(DDE) attacks10.
9
https://docs.microsoft.com/en-au/windows/threat-protection/windows-defender-exploit-guard/attack-surfacereduction-exploit-guard
10
https://docs.microsoft.com/en-au/security-updates/securityadvisories/2017/4053440
10
For organisations using Windows Defender Antivirus, the following Group Policy settings can be implemented to
enforce the above ASR rules.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
Windows Defender Exploit Guard\Attack Surface Reduction
Configure Attack Surface Reduction rules
Enabled
Set the state for each ASR rule:
75668c1f-73b5-4cf0-bb93-3ecf5cb7cc84
1
3b576869-a4ec-4529-8536-b80a7769e899
1
d4f940ab-401b-4efc-aadc-ad5f3c50688a
1
92E97FA1-2EDF-4476-BDD6-9DD0B4DDDC7B
1
5beb7efe-fd9a-4556-801d-275e5ffc04cc
1
d3e037e1-3eb8-44c8-a917-57927947596d
1
be9ba2d9-53ea-4cdc-84e5-9b1eeee46550
1
Credential caching
Cached credentials are stored in the Security Accounts Manager (SAM) database and can allow a user to log onto a
workstation they have previously logged onto even if the domain is not available. Whilst this functionality may be
desirable from an availability of services perspective, this functionality can be abused by an adversary who can retrieve
these cached credentials (potentially Domain Administrator credentials in a worst-case scenario). To reduce this risk,
cached credentials should be limited to only one previous logon.
The following Group Policy settings can be implemented to disable credential caching.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Interactive logon: Number of previous logons to cache
(in case domain controller is not available)
1 logons
Network access: Do not allow storage of passwords and
credentials for network authentication
Enabled
Within an active user session, credentials are cached within the Local Security Authority Subsystem Service (LSASS)
process (including the user’s passphrase in plaintext if WDigest authentication is enabled) to allow for access to
network resources without users having to continually enter their credentials. Unfortunately, these credentials are at
risk of theft by an adversary. To reduce this risk, WDigest authentication should be disabled.
Credential Guard11, a security feature of Microsoft Windows 10 version 1709, is also designed to assist in protecting the
LSASS process.
11
https://docs.microsoft.com/en-au/windows/security/identity-protection/credential-guard/credential-guard
11
The following Group Policy settings can be implemented to disable WDigest authentication and enable Credential
Guard functionality, assuming all software, firmware and hardware pre-requests are met.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\MS Security Guide
WDigest Authentication
Disabled
Computer Configuration\Policies\Administrative Templates\System\Device Guard
Turn On Virtualization Based Security
Enabled
Select Platform Security Level: Secure Boot and DMA
Protection
Credential Guard Configuration: Enabled with UEFI lock
Controlled Folder Access
Controlled Folder Access12 is a security feature in Microsoft Windows 10 version 1709 that forms part of Windows
Defender Exploit Guard. It is designed to combat the threat of ransomware.
In order to use Controlled Folder Access, Windows Defender Antivirus must be configured as the primary real-time
antivirus scanning engine on workstations. Other third party antivirus solutions may offer similar functionality as part of
their offerings.
The following Group Policy settings can be implemented to implement Controlled Folder Access.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
Windows Defender Exploit Guard\Controlled Folder Access
Configure allowed applications
Enabled
Enter the applications that should be trusted:
<organisation defined>
Configure Controlled folder access
Enabled
Configure the guard my folders feature: Block
Configure protected folders
Enabled
Enter the folders that should be guarded: <organisation
defined>
12
https://docs.microsoft.com/en-au/windows/security/threat-protection/windows-defender-exploit-guard/controlled-folders-exploit-guard
12
Credential entry
When users enter their credentials on a workstation it provides an opportunity for malicious code, such as a key logging
application, to capture the credentials. To reduce this risk, users should be authenticated by using a trusted path to
enter their credentials on the Secure Desktop.
The following Group Policy settings can be implemented to ensure credentials are entered in a secure manner as well
as prevent the disclosure of usernames of previous users.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Logon
Do not display network selection UI
Enabled
Enumerate local users on domain-joined computers
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Credential User Interface
Do not display the password reveal button
Enabled
Enumerate administrator accounts on elevation
Disabled
Require trusted path for credential entry
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Logon Options
Disable or enable software Secure Attention Sequence
Disabled
Sign-in last interactive user automatically after a systeminitiated restart
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Interactive logon: Do not require CTRL+ALT+DEL
Disabled
Interactive logon: Don’t display username at sign-in
Enabled
Early Launch Antimalware
Another key security feature of Trusted Boot supported by Microsoft Windows 10 version 1709 and motherboards with
an Unified Extensible Firmware Interface (UEFI) is Early Launch Antimalware (ELAM)13. Used in conjunction with Secure
Boot, an ELAM driver can be registered as the first non-Microsoft driver that will be initialised on a workstation as part
of the boot process, thus allowing it to verify all subsequent drivers before they are initialised. The ELAM driver is
capable of allowing only known good drivers to initialise; known good and unknown drivers to initialise; known good,
13
https://docs.microsoft.com/en-au/windows/security/information-protection/secure-the-windows-10-boot-process
13
unknown and bad but critical drivers to initialise; or all drivers to initialise. To reduce the risk of malicious drivers, only
known good drivers should be allowed to be initialised during the boot process.
The following Group Policy setting can be implemented to ensure only known good drivers will be initialised at boot
time.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Early Launch Antimalware
Boot-Start Driver Initialization Policy
Enabled
Choose the boot-start drivers that can be initialized:
Good and unknown
Elevating privileges
Microsoft Windows provides the ability to require confirmation from users, via the User Access Control (UAC)
functionality, before any sensitive actions are performed. The default settings allow privileged users to perform
sensitive actions without first providing credentials and while standard users must provide privileged credentials they
are not required to do so via a trusted path on the Secure Desktop. This provides an opportunity for an adversary that
gains access to an open session of a privileged user to perform sensitive actions at will or for malicious code to capture
any credentials entered via a standard user when attempting to elevate their privileges. To reduce this risk, UAC
functionality should be implemented to ensure all sensitive actions are authorised by providing credentials on the
Secure Desktop.
The following Group Policy settings can be implemented to configure UAC functionality effectively.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
User Account Control: Admin Approval Mode for the
Built-in Administrator account
Enabled
User Account Control: Allow UIAccess applications to
prompt for elevation without using the secure desktop
Disabled
User Account Control: Behavior of the elevation prompt
for administrators in Admin Approval Mode
Prompt for credentials on the secure desktop
User Account Control: Behavior of the elevation prompt
for standard users
Prompt for credentials on the secure desktop
User Account Control: Detect application installations
and prompt for elevation
Enabled
User Account Control: Only elevate UIAccess applications
that are installed in secure locations
Enabled
14
User Account Control: Run all administrators in Admin
Approval Mode
Enabled
User Account Control: Switch to the secure desktop
when prompting for elevation
Enabled
User Account Control: Virtualize file and registry write
failures to per-user locations
Enabled
Exploit Protection
An adversary that develops exploits for Microsoft Windows or third party applications will have a higher success rate
when security measures designed by Microsoft to help prevent security vulnerabilities from being exploited are not
implemented. Windows Defender Exploit Guard’s Exploit Protection14 functionality was introduced in Microsoft
Windows 10 version 1709 to provide system-wide and application-specific security measures. Exploit Protection is
designed to replace the Enhanced Mitigation Experience Toolkit (EMET) that was used on earlier versions of Microsoft
Windows 10.
System-wide security measures configurable via Exploit Protection include: Control Flow Guard (CFG), Data Execution
Prevention (DEP), mandatory Address Space Layout Randomization (ASLR), bottom-up ASLR, Structured Exception
Handling Overwrite Protection (SEHOP) and heap corruption protection. Many more application-specific security
measures are also available.
The following Group Policy settings can be implemented to define Exploit Protection settings and to prevent users from
modifying these settings on their devices.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Exploit
Guard\Exploit Protection
Use a common set of exploit protection settings
Enabled
Type the location (local path, UNC path, or URL) of the
mitigation settings configuration XML file: <organisation
defined>
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Security
Center\App and browser protection
Prevent users from modifying settings
Enabled
In addition, the following Group Policy setting can be implemented to ensure DEP is not disabled for File Explorer.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\File Explorer
14
https://docs.microsoft.com/en-au/windows/threat-protection/windows-defender-exploit-guard/exploit-protectionexploit-guard
15
Turn off Data Execution Prevention for Explorer
Disabled
Furthermore, the following Group Policy setting can be implemented to force the use of SEHOP.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\MS Security Guide
Enabled Structured Exception Handling Overwrite
Protection (SEHOP)
Enabled
Local administrator accounts
When built-in administrator accounts are used with common account names and passwords it can allow an adversary
that compromises these credentials on one workstation to easily transfer across the network to other workstations.
Even if built-in administrator accounts are uniquely named and have unique passwords, an adversary can still identify
these accounts based on their security identifier (i.e. S-1-5-21-domain-50015) and use this information to focus any
attempts to brute force credentials on a workstation if they can get access to the SAM database. To reduce this risk,
built-in administrator accounts should be disabled. Instead, domain accounts with local administrative privileges, but
without domain administrative privileges, should be used for workstation management.
The following Group Policy setting can be implemented to disable built-in administrator accounts.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Accounts: Administrator account status
Disabled
If a common local administrator account absolutely must be used for workstation management then Microsoft’s Local
Administrator Password Solution (LAPS)16 needs to be used to ensure unique passphrases are used for each
workstation. In addition, User Account Control restrictions should be applied to remote connections using such
accounts.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\MS Security Guide
Apply UAC restrictions to local accounts on network
logons
Enabled
Measured Boot
The third key security feature of Trusted Boot supported by Microsoft Windows 10 version 1709 and motherboards
with both an UEFI and a Trusted Processing Module (TPM) is Measured Boot 17. Measured Boot is used to develop a
reliable log of components that are initialised before the ELAM driver. This information can then be scrutinised by
15
https://support.microsoft.com/en-au/help/243330/well-known-security-identifiers-in-windows-operating-systems
https://www.microsoft.com/en-au/download/details.aspx?id=46899
17
https://docs.microsoft.com/en-au/windows/security/information-protection/secure-the-windows-10-boot-process
16
16
antimalware software for signs of tampering of boot components. To reduce the risk that malicious changes to boot
components go unnoticed, Measured Boot should be used on workstations that support it.
Microsoft Edge
Microsoft Edge is a web browser that was first introduced in Microsoft Windows 10 to replace Internet Explorer.
Microsoft Edge contains significant security enhancements over Internet Explorer and should be used wherever
possible.
Internet Explorer 11’s use should be restricted to supporting any legacy web applications hosted on corporate
intranets. If Internet Explorer 11 is not required, it should be uninstalled from Microsoft Windows 10 to reduce the
operating system’s attack surface.
For organisations using Microsoft Edge instead of third party web browsers, the following Group Policy settings can be
implemented to harden Microsoft Edge, including Windows Defender SmartScreen 18.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Microsoft Edge
Allow Adobe Flash
Disabled
Allow Developer Tools
Disabled
Configure Do Not Track
Enabled
Configure Password Manager
Disabled
Configure Pop-up Blocker
Enabled
Configure Windows Defender SmartScreen
Enabled
Prevent access to the about:flags page in Microsoft Edge
Enabled
Prevent bypassing Windows Defender SmartScreen
prompts for files
Enabled
Prevent bypassing Windows Defender SmartScreen
prompts for sites
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
Windows Defender Exploit Guard\Network Protection
Prevent users and apps from accessing dangerous
websites
Enabled
Block
18
https://docs.microsoft.com/en-au/windows/security/threat-protection/windows-defender-smartscreen/windowsdefender-smartscreen-overview
17
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender
Application Guard
Turn on Windows Defender Application Guard in
Enterprise Mode
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender
SmartScreen\Microsoft Edge
Configure Windows Defender SmartScreen
Enabled
Prevent bypassing Windows Defender SmartScreen
prompts for sites
Enabled
Multi-factor authentication
As privileged credentials often allow users to bypass security functionality put in place to protect workstations, and are
susceptible to key logging applications, it is important that they are appropriately protected against compromise. In
addition, an adversary that brute forces captured password hashes can gain access to workstations if multi-factor
authentication hasn’t been implemented. To reduce this risk, hardware-based multi-factor authentication should be
used for users as they perform a privileged action or access any important or sensitive data repositories.
For more information on how to effectively implement multi-factor authentication see the Implementing MultiFactor Authentication publication19.
Operating system architecture
The x64 (64-bit) versions of Microsoft Windows include additional security functionality that the x86 (32-bit) versions
lack. This includes native hardware-based Data Execution Prevention (DEP) kernel support, Kernel Patch Protection
(PatchGuard), mandatory device driver signing and lack of support for malicious 32-bit drivers. Using x86 (32-bit)
versions of Microsoft Windows exposes organisations to exploit techniques mitigated by x64 (64-bit) versions of
Microsoft Windows. To reduce this risk, workstations should use the x64 (64-bit) versions of Microsoft Windows.
Operating system patching
Patches are released either in response to previously disclosed security vulnerabilities or to proactively address security
vulnerabilities that have not yet been publicly disclosed. In the case of disclosed security vulnerabilities, it is possible
that exploits have already been developed and are freely available in common hacking tools. In the case of patches for
security vulnerabilities that have not yet been publically disclosed, it is relatively easy for an adversary to use freely
available tools to identify the security vulnerability being patched and develop an associated exploit. This activity can be
undertaken in less than one day and has led to an increase in 1-day attacks. To reduce this risk, operating system
patches and driver updates should be centrally managed and deployed in an appropriate timeframe as determined by
the severity of the security vulnerability and any mitigating measures already in place. This can be achieved using
Microsoft System Center Configuration Manager (SCCM)20. Microsoft Windows Server Update Services (WSUS) 21 can
also centrally deploy patches but only for Microsoft applications.
19
https://www.acsc.gov.au/publications/protect/Multi_Factor_Authentication.pdf
https://www.microsoft.com/en-au/cloud-platform/system-center-configuration-manager
21
https://docs.microsoft.com/en-au/windows-server/administration/windows-server-update-services/getstarted/windows-server-update-services-wsus
20
18
For more information on determining the severity of security vulnerabilities and timeframes for applying patches see
the Assessing Security Vulnerabilities and Applying Patches publication22.
The following Group Policy settings can be implemented to ensure operating systems remain appropriately patched.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Update
Allow Automatic Updates immediate installation
Enabled
Configure Automatic Updates
Enabled
Configure automatic updating: 4 - Auto download and
schedule the install
Schedule install day: 0 - Every day
Install updates for other Microsoft products
Do not include drivers with Windows Updates
Disabled
No auto-restart with logged on users for scheduled
automatic updates installations
Enabled
Remove access to use all Windows Update features
Disabled
Turn on recommended updates via Automatic Updates
Enabled
Furthermore, if a Windows Server Update Services (WSUS) server is used, the following Group Policy setting can be
implemented.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Update
Specify intranet Microsoft update service location
Enabled
Set the intranet update service for detecting updates:
<server:port>
Alternatively, if System Centre Configuration Manager (SCCM) is used instead of Microsoft update servers or a WSUS
server, equivalent settings can be implemented to achieve a similar outcome.
Operating system version
Microsoft Windows 10 has introduced improvements in security functionality over previous versions of Microsoft
Windows23. This has made it more difficult for an adversary to craft reliable exploits for security vulnerabilities they
discovered. Using older versions of Microsoft Windows, including previous versions of Microsoft Windows 10, exposes
22
https://www.acsc.gov.au/publications/protect/Assessing_Security_Vulnerabilities_and_Applying_Patches.pdf
https://docs.microsoft.com/en-au/windows/security/threat-protection/overview-of-threat-mitigations-in-windows10
23
19
organisations to exploit techniques that have since been mitigated in newer versions of Microsoft Windows. To reduce
this risk, workstations should use the latest version of Microsoft Windows 10.
Password policy
The use of weak passwords, such as eight character passwords with no complexity, can allow them to be brute forced
within minutes using applications freely available on the Web. In addition, having no maximum password age can allow
an adversary to maintain extended access to a workstation or network once a password has been compromised while
having no minimum password age can allow an adversary to recycle passwords if forced to change them due to
maximum password ages. To reduce this risk, a secure password policy should be implemented.
The following Group Policy settings can be implemented to achieve a secure password policy.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Logon
Turn off picture password sign-in
Enabled
Turn on convenience PIN sign-in
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Account Policies\Password Policy
Enforce password history
8 passwords remembered
Maximum password age
90 days
Minimum password age
1 days
Minimum password length
10 characters
Password must meet complexity requirements
Enabled
Store passwords using reversible encryption
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Accounts: Limit local account use of blank passwords to
console logon only
Enabled
Restricting privileged accounts
Providing users with a privileged account for day to day usage poses a risk that they will use this account for external
web and email access. This is of particular concern as privileged users have the ability to execute malicious code with
privileged access rather than standard access. To reduce this risk, users that don’t require privileged access should not
be granted privileged accounts while users that require privileged access should have separate standard and privileged
accounts with different credentials. In addition, any privileged accounts used should have external web and email
access blocked.
20
For more information on the use of privileged accounts and minimising their usage see the Restricting Administrative
Privileges publication24.
Secure Boot
Another method for malicious code to maintain persistence and prevent detection is to replace the default boot loader
for Microsoft Windows with a malicious version. In such cases the malicious boot loader executes at boot time and
loads Microsoft Windows without any indication that it is present. Such malicious boot loaders are extremely difficult to
detect and can be used to conceal malicious code on workstations. To reduce this risk, motherboards with Secure Boot
functionality should be used. Secure Boot, a component of Trusted Boot, is a security feature supported by Microsoft
Windows 10 version 1709 and motherboards with an UEFI25. Secure Boot works by checking at boot time that the boot
loader is signed and matches a Microsoft signed certificate stored in the UEFI. If the certificate signatures match the
boot loader is allowed to run, otherwise it is prevented from running and the workstation will not boot.
24
25
https://www.acsc.gov.au/publications/protect/Restricting_Admin_Privileges.pdf
https://docs.microsoft.com/en-au/windows/security/information-protection/secure-the-windows-10-boot-process
21
Medium priorities
The following security controls, listed in alphabetical order, are considered to have a very good effectiveness and
should be treated as medium priorities when hardening Microsoft Windows 10 version 1709 workstations.
Account lockout policy
Allowing unlimited attempts to access workstations will fail to prevent an adversary’s attempts to brute force
authentication measures. To reduce this risk, accounts should be locked out after a defined number of invalid
authentication attempts. The threshold for locking out accounts does not need to be overly restrictive in order to be
effective. For example, a threshold of 5 incorrect attempts, with a reset period of 15 minutes for the lockout counter,
will prevent any brute force attempt while being unlikely to lock out a legitimate user who accidently enters their
password incorrectly a few times.
The following Group Policy settings can be implemented to achieve a reasonable lockout policy.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Account Policies\Account Lockout Policy
Account lockout duration
0
Account lockout threshold
5 invalid logon attempts
Reset account lockout counter after
15 minutes
Anonymous connections
An adversary can use anonymous connections to gather information about the state of workstations. Information that
can be gathered from anonymous connections (i.e. using the net use command to connect to the IPC$ share) can
include lists of users and groups, SIDs for accounts, lists of shares, workstation policies, operating system versions and
patch levels. To reduce this risk, anonymous connections to workstations should be disabled.
The following Group Policy settings can be implemented to disable the use of anonymous connections.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Network\Lanman Workstation
Enable insecure guest logons
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Network access: Allow anonymous SID/Name translation
Disabled
Network access: Do not allow anonymous enumeration
of SAM accounts
Enabled
22
Network access: Do not allow anonymous enumeration
of SAM accounts and shares
Enabled
Network access: Let Everyone permissions apply to
anonymous users
Disabled
Network access: Restrict anonymous access to Named
Pipes and Shares
Enabled
Network access: Restrict clients allowed to make remote
calls to SAM
O:BAG:BAD:(A;;RC;;;BA)
Network security: Allow Local System to use computer
identity for NTLM
Enabled
Network security: Allow LocalSystem NULL session
fallback
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Access this computer from the network
Administrators
Remote Desktop Users
Deny access to this computer from the network
Guests
NT AUTHORITY\Local Account
Antivirus software
An adversary can develop malicious code to exploit security vulnerabilities in software not detected and remedied by
vendors during testing. As significant time and effort is often involved in the development of functioning and reliable
exploits, an adversary will often reuse their exploits as much as possible before being forced to develop new exploits.
To reduce this risk, endpoint security applications with signature-based antivirus functionality should be implemented.
In doing so, signatures should be updated at least on a daily basis.
Whilst using signature-based antivirus functionality can assist in reducing risk, they are only effective when a particular
piece of malicious code has already been profiled and signatures are current. An adversary can create variants of
known malicious code, or develop new unseen malicious code, to bypass traditional signature-based detection
mechanisms. To reduce this risk, endpoint security applications with host-based intrusion prevention functionality, or
equivalent functionality leveraging cloud-based services, should also be implemented. In doing so, such functionality
should be set at the highest level available.
If using Microsoft’s Windows Defender Antivirus solution 26, the following Group Policy settings can be implemented to
optimally configure it.
26
https://docs.microsoft.com/en-au/windows/security/threat-protection/windows-defender-antivirus/windowsdefender-antivirus-in-windows-10
23
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus
Turn off Windows Defender Antivirus
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
MAPS
Configure local setting override for reporting to
Microsoft MAPS
Disabled
Configure the ‘Block at First Sight’ feature
Enabled
Join Microsoft MAPS
Enabled
Join Microsoft MAPS: Advanced MAPS
Send file samples when further analysis is required
Enabled
Send file samples when further analysis is required: Send
safe samples
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
MpEngine
Configure extended cloud check
Enabled
Specify the extended cloud check time in seconds: 50
Select cloud protection level
Enabled
Select cloud blocking level: High blocking level or High+
blocking level
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
Quarantine
Configure removal of items from Quarantine folder
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
Real-time Protection
Scan all downloaded files and attachments
Enabled
Turn off real-time protection
Disabled
Turn on behavior monitoring
Enabled
24
Turn on process scanning whenever real-time protection
is enabled
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\
Scan
Allow users to pause scan
Disabled
Check for the latest virus and spyware definitions before
running a scheduled scan
Enabled
Scan archive files
Enabled
Scan packed executables
Enabled
Scan removable drives
Enabled
Turn on e-mail scanning
Enabled
Turn on heuristics
Enabled
Attachment Manager
The Attachment Manager within Microsoft Windows works in conjunction with applications such as the Microsoft
Office suite and Internet Explorer to help protect workstations from attachments that have been received via email or
downloaded from the Internet. The Attachment Manager classifies files as high, medium or low risk based on the zone
they originated from and the type of file. Based on the risk to the workstation, the Attachment Manager will either
issue a warning to a user or prevent them from opening a file. If zone information is not preserved, or can be removed,
it can allow an adversary to socially engineer a user to bypass protections afforded by the Attachment Manager. To
reduce this risk, the Attachment Manager should be configured to preserve and protect zone information for files.
The following Group Policy settings can be implemented to ensure zone information associated with attachments is
preserved and protected.
Group Policy Setting
Recommended Option
User Configuration\Policies\Administrative Templates\Windows Components\Attachment Manager
Do not preserve zone information in file attachments
Disabled
Hide mechanisms to remove zone information
Enabled
Audit event management
Failure to capture and analyse security related audit events from workstations can result in intrusions going unnoticed.
In addition, the lack of such information can significantly hamper investigations following a security incident. To reduce
this risk, security related audit events from workstations should be captured and routinely analysed.
25
The following Group Policy settings can be implemented to ensure security related audit events are appropriately
captured.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Audit Process Creation
Include command line in process creation events
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Event Log Service\Application
Specify the maximum log file size (KB)
Enabled
Maximum Log Size (KB): 65536
Computer Configuration\Policies\Administrative Templates\Windows Components\Event Log Service\Security
Specify the maximum log file size (KB)
Enabled
Maximum Log Size (KB): 2097152
Computer Configuration\Policies\Administrative Templates\Windows Components\Event Log Service\System
Specify the maximum log file size (KB)
Enabled
Maximum Log Size (KB): 65536
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Manage auditing and security log
Administrators
Furthermore, the following Group Policy settings can be implemented to enable a comprehensive auditing strategy.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit
Policies\Account Management
Audit Computer Account Management
Success and Failure
Audit Other Account Management Events
Success and Failure
Audit Security Group Management
Success and Failure
Audit User Account Management
Success and Failure
Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit
Policies\Detailed Tracking
Audit Process Creation
Success
26
Audit Process Termination
Success
Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit
Policies\Logon/Logoff
Audit Account Lockout
Success
Audit Group Membership
Success
Audit Logoff
Success
Audit Logon
Success and Failure
Audit Other Logon/Logoff Events
Success and Failure
Audit Special Logon
Success and Failure
Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit
Policies\Object Access
Audit File Share
Success and Failure
Audit File System
Success and Failure
Audit Kernel Object
Success and Failure
Audit Other Object Access Events
Success and Failure
Audit Registry
Success and Failure
Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit
Policies\Policy Change
Audit Audit Policy Change
Success and Failure
Audit Other Policy Change Events
Success and Failure
Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit
Policies\System
Audit System Integrity
Success and Failure
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Audit: Force audit policy subcategory settings (Windows
Vista or later) to override audit policy category settings
Enabled
27
Autoplay and AutoRun
When enabled, Autoplay will automatically begin reading from a drive or media source as soon as it is used with a
workstation, while AutoRun commands, generally in an autorun.inf file on the media, can be used to automatically
execute any file on the media without user interaction. This functionality can be exploited by an adversary to
automatically execute malicious code. To reduce this risk, Autoplay and AutoRun functionality should be disabled.
The following Group Policy settings can be implemented to disable Autoplay and AutoRun functionality.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\AutoPlay Policies
Disallow Autoplay for non-volume devices
Enabled
Set the default behavior for AutoRun
Enabled
Default AutoRun Behavior: Do not execute any autorun
commands
Turn off Autoplay
Enabled
Turn off Autoplay on: All drives
BIOS and UEFI passwords
An adversary with access to a workstation’s Basic Input/Output System (BIOS) or UEFI can modify the hardware
configuration of the workstation to introduce attack vectors or weaken security functionality within the workstation’s
operating system. This can include disabling security functionality in the CPU, modifying allowed boot devices and
enabling insecure communications interfaces such as FireWire and Thunderbolt. To reduce this risk, strong BIOS and
UEFI passwords should be used for all workstations to prevent unauthorised access.
Boot devices
By default, workstations are often configured to boot from optical media, or even USB media, in preference to hard
drives. An adversary with physical access to such workstations can boot from their own media in order to gain access to
the content of the hard drives. With this access, an adversary can reset local user account passwords or gain access to
the local SAM database to steal password hashes for offline brute force cracking attempts. To reduce this risk,
workstations should be restricted to only booting from the designated primary system drive.
Bridging networks
When workstations have multiple network interfaces, such as an Ethernet interface and a wireless interface, it is
possible to establish a bridge between the connected networks. For example, when using an Ethernet interface to
connect to an organisation’s wired network and a wireless interface to connect to another non-organisation controlled
network such as a public wireless hotspot. When bridges are created between such networks an adversary can directly
access the wired network from the wireless network to extract sensitive information. To reduce this risk, the ability to
install and configure network bridges between different networks should be disabled. This won’t prevent an adversary
from compromising a workstation via the wireless network and then using malicious software as a medium to indirectly
access the wired network. This can only be prevented by manually disabling all wireless interfaces when connecting to
wired networks.
28
The following Group Policy settings can be implemented to disable the ability to install and configure network bridges.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Network\Network Connections
Prohibit installation and configuration of Network Bridge
on your DNS domain network
Enabled
Route all traffic through the internal network
Enabled
Select from the following states: Enabled State
Computer Configuration\Policies\Administrative Templates\Network\Windows Connection Manager
Prohibit connection to non-domain networks when
connected to domain authenticated network
Enabled
Built-in guest accounts
When built-in guest accounts are used, it can allow an adversary to log onto a workstation over the network without
first needing to compromise legitimate user credentials. To reduce this risk, built-in guest accounts should be disabled.
The following Group Policy settings can be implemented to disable and rename built-in guest accounts.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Accounts: Guest account status
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Deny log on locally
Guests
Case locks
Without the use of case locks an adversary can gain physical access to the insides of a workstation. An adversary with
this access can install or remove hardware, remove and replace the CMOS battery to reset the BIOS or UEFI to default
settings (i.e. no password), or temporarily remove hard drives to create copies for offline analysis at a later date. To
reduce this risk, case locks should be used on workstations to prevent an adversary from gaining unauthorised access.
CD burner access
If CD burning functionality is enabled, and CD burners are installed in workstations, an adversary may attempt to steal
sensitive information by burning it to CD. To reduce this risk, users should not have access to CD burning functionality
except when explicitly required.
The following Group Policy setting can be implemented to prevent access to CD burning functionality, although as this
Group Policy setting only prevents access to native CD burning functionality in Microsoft Windows, users should also be
29
prevented from installing third party CD burning applications. Alternatively, CD readers can be used in workstations
instead of CD burners.
Group Policy Setting
Recommended Option
User Configuration\Policies\Administrative Templates\Windows Components\File Explorer
Remove CD Burning features
Enabled
Centralised audit event logging
Storing audit event logs on workstations poses a risk that an adversary could attempt to modify or delete these logs
during an intrusion to cover their tracks. In addition, failure to conduct centralised audit event logging will reduce the
visibility of audit events across all workstations, prevent the correlation of audit events and increase the complexity of
any investigations after security incidents. To reduce this risk, audit event logs from workstations should be transferred
to a secure central logging server.
Command Prompt
An adversary who gains access to a workstation can use the Command Prompt to execute in-built Microsoft Windows
tools to gather information about the workstation or domain as well as schedule malicious code to execute on other
workstations on the network. To reduce this risk, users should not have Command Prompt access or the ability to
execute batch files and scripts. Should a legitimate business requirement exist to allow users to execute batch files (e.g.
cmd and bat files); run logon, logoff, startup or shutdown batch file scripts; or use Remote Desktop Services, this risk
will need to be accepted.
The following Group Policy setting can be implemented to prevent access to the Command Prompt and script
processing functionality.
Group Policy Setting
Recommended Option
User Configuration\Policies\Administrative Templates\System
Prevent access to the command prompt
Enabled
Disable the command prompt script processing also: Yes
Direct Memory Access
Communications interfaces that use Direct Memory Access (DMA) can allow an adversary with physical access to a
workstation to directly access the contents of a workstation’s memory. This can be used to read sensitive contents such
as cryptographic keys or to write malicious code directly into memory. To reduce this risk, communications interfaces
that allow DMA (e.g. FireWire and Thunderbolt) should be disabled. This can be achieved either physically (e.g. using
epoxy) or by using software controls27 (e.g. disabling the functionality in the BIOS or UEFI; removing the SBP-2 driver
and disabling the Thunderbolt controller; or using an end point protection solution).
The following Group Policy settings can be implemented to remove the SBP-2 driver and disable the Thunderbolt
controller.
27
https://support.microsoft.com/en-au/help/2516445/blocking-the-sbp-2-driver-and-thunderbolt-controllers-toreduce-1394-d
30
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Device Installation\Device Installation
Restrictions
Prevent installation of devices that match any of these
device IDs
Enabled
Prevent installation of devices that match any of these
Device IDs: PCI\CC_0C0A
Also apply to matching devices that are already installed.
Prevent installation of devices using drivers that match
these device setup classes
Enabled
Prevent installation of devices using drivers for these
device setup classes:
{d48179be-ec20-11d1-b6b8-00c04fa372a7}
Also apply to matching devices that are already installed.
Endpoint device control
An adversary with physical access to a workstation may attempt to connect unauthorised USB media or other devices
with mass storage functionality (e.g. smartphones, digital music players or cameras) to facilitate malicious code
infections or the unauthorised copying of sensitive information. To reduce this risk, endpoint device control
functionality should be appropriately implemented to control the use of all removable storage devices.
The following Group Policy setting can be implemented to disable the use of removable storage devices.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Removable Storage Access
All Removable Storage classes: Deny all access
Enabled
Alternatively, if specific classes of removable storage devices are required to meet business requirements, the execute,
read and write permissions should be controlled on a class by class basis.
The following Group Policy settings provide a sample implementation that allows data to be read from but not
executed from or written to all classes of removable storage devices.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Removable Storage Access
CD and DVD: Deny execute access
Enabled
CD and DVD: Deny read access
Disabled
CD and DVD: Deny write access
Enabled
Custom Classes: Deny read access
Disabled
31
Custom Classes: Deny write access
Enabled
Floppy Drives: Deny execute access
Enabled
Floppy Drives: Deny read access
Disabled
Floppy Drives: Deny write access
Enabled
Removable Disks: Deny execute access
Enabled
Removable Disks: Deny read access
Disabled
Removable Disks: Deny write access
Enabled
Tape Drives: Deny execute access
Enabled
Tape Drives: Deny read access
Disabled
Tape Drives: Deny write access
Enabled
WPD Devices: Deny read access
Disabled
WPD Devices: Deny write access
Enabled
File and print sharing
Users sharing files from their workstations can result in a lack of appropriate access controls being applied to sensitive
information and the potential for the propagation of malicious code should file shares have read/write access. To
reduce this risk, local file and print sharing should be disabled. Ideally, sensitive information should be centrally
managed (e.g. on a network share with appropriate access controls). Disabling file and print sharing will not affect a
user’s ability to access shared drives and printers on a network.
The following Group Policy settings can be implemented to prevent users from sharing files.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\HomeGroup
Prevent the computer from joining a homegroup
Enabled
User Configurations\Policies\Administrative Templates\Windows Components\Network Sharing
Prevent users from sharing files within their profile.
Enabled
Group Policy processing
Relying on users to set Group Policy settings for their workstations creates the potential for users to inadvertently
misconfigure or disable security functionality without consideration of the impact on the security posture of the
32
workstation. Alternatively, an adversary could exploit this to disable any Local Group Policy settings that are hampering
their efforts to extract sensitive information. To reduce this risk, all audit, user rights and security related Group Policy
settings should be specified for workstations at an organisational unit or domain level. To ensure these policies aren’t
weakened, support for Local Group Policy settings should also be disabled.
The following Group Policy settings can be implemented to ensure only domain-based Group Policy settings are applied
to workstations.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Network\Network Provider
Hardened UNC Paths
Enabled
Hardened UNC Paths:
\\*\SYSVOL
RequireMutualAuthentication=1, RequireIntegrity=1
\\*\NETLOGON
RequireMutualAuthentication=1, RequireIntegrity=1
Computer Configuration\Policies\Administrative Templates\System\Group Policy
Configure registry policy processing
Enabled
Process even if the Group Policy objects have not
changed
Configure security policy processing
Enabled
Process even if the Group Policy objects have not
changed
Turn off background refresh of Group Policy
Disabled
Turn off Local Group Policy Objects processing
Enabled
Hard drive encryption
An adversary with physical access to a workstation may be able to use a bootable CD/DVD or USB media to load their
own operating environment. From this environment, they can access the local file system to gain access to sensitive
information or the SAM database to access password hashes. In addition, an adversary that gains access to a stolen or
unsanitised hard drive will be to recover its contents when connected to another machine on which they have
administrative access and can take ownership of files. To reduce this risk, 256-bit AES full disk encryption should be
used to protect the contents of hard drives from unauthorised access.
If Microsoft BitLocker is used, the following Group Policy settings should be implemented.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\BitLocker Drive Encryption
33
Choose drive encryption method and cipher strength
(Windows 10 [Version 1511] and later)
Enabled
Select the encryption method for operating system
drives: XTS-AES 256-bit
Select the encryption method for fixed data drives: XTSAES 256-bit
Select the encryption method for removable data drives:
XTS-AES 256-bit
Disable new DMA devices when this computer is locked
Enabled
Prevent memory overwrite on restart
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\BitLocker Drive Encryption\
Fixed Data Drives
Choose how BitLocker-protected fixed drives can be
recovered
Enabled
Allow data recovery agent
Configure user storage of BitLocker recovery
information:
Allow 48-digit recovery password
Allow 256-bit recovery key
Omit recovery options from the BitLocker setup wizard
Save BitLocker recovery information to AD DS for fixed
data drives
Configure storage of BitLocker recovery information to
AD DS: Backup recovery passwords and key packages
Do not enable BitLocker until recovery information is
stored to AD DS for fixed data drives
Configure use of passwords for fixed data drives
Enabled
Require password for fixed data drive
Configure password complexity for fixed data drives:
Require password complexity
Minimum password length for fixed data drive: 10
Deny write access to fixed drives not protected by
BitLocker
Enabled
Enforce drive encryption type on fixed data drives
Enabled
Select the encryption type: Full encryption
Computer Configuration\Policies\Administrative Templates\Windows Components\BitLocker Drive Encryption\
Operating System Drives
34
Allow devices compliant with InstantGo or HSTI to opt
out of pre-boot PIN.
Disabled
Allow enhanced PINs for startup
Enabled
Allow network unlocked at startup
Enabled
Allow Secure Boot for integrity validation
Enabled
Choose how BitLocker-protected operating system
drives can be recovered
Enabled
Allow data recovery agent
Configure user storage of BitLocker recovery
information:
Allow 48-digit recovery password
Allow 256-bit recovery key
Omit recovery options from the BitLocker setup wizard
Save BitLocker recovery information to AD DS for
operating system drives
Configure storage of BitLocker recovery information to
AD DS: Backup recovery passwords and key packages
Do not enable BitLocker until recovery information is
stored to AD DS for operating system drives
Configure minimum PIN length for startup
Enabled
Minimum characters: 13
Configure use of passwords for operating system drives
Enabled
Configure password complexity for operating system
drives: Require password complexity
Minimum password length for operating system drive:
10
Disallow standard users from changing the PIN or
password
Disabled
Enforce drive encryption type on operating system
drives
Enabled
Require additional authentication at startup
Enabled
Select the encryption type: Full encryption
Allow BitLocker without a compatible TPM (requires a
password or a startup key on a USB flash drive)
Settings for computers with a TPM
Configure TPM startup: Do not allow TPM
Configure TPM startup PIN: Allow startup PIN with TPM
35
Configure TPM startup key: Allow startup key with TPM
Configure TPM startup key and PIN: Allow startup key
and PIN with TPM
Reset platform validation data after BitLocker recovery
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\BitLocker Drive Encryption\
Removable Data Drives
Choose how BitLocker-protected removable drives can
be recovered
Enabled
Allow data recovery agent
Configure user storage of BitLocker recovery
information:
Allow 48-digit recovery password
Allow 256-bit recovery key
Omit recovery options from the BitLocker setup wizard
Save BitLocker recovery information to AD DS for
removable data drives
Configure storage of BitLocker recovery information to
AD DS: Backup recovery passwords and key packages
Do not enable BitLocker until recovery information is
stored to AD DS for removable data drives
Configure use of passwords for removable data drives
Enabled
Require password for removable data drive
Configure password complexity for removable data
drives: Require password complexity
Minimum password length for removable data drive: 10
Control use of BitLocker on removable drives
Enabled
Allow users to apply BitLocker protection on removable
data drives
Deny write access to removable drives not protected by
BitLocker
Enabled
Enforce drive encryption type on removable data drives
Enabled
Select the encryption type: Full encryption
Installing applications
While the ability to install applications may be a business requirement for users, this privilege can be exploited by an
adversary. An adversary can email a malicious application, or host a malicious application on a compromised website,
and use social engineering techniques to convince users into installing the application on their workstation. Even if
privileged access is required to install applications, users will use their privileged access if they believe, or can be
convinced that, the requirement to install the application is legitimate. Additionally, if applications are configured to
36
install using elevated privileges, an adversary can exploit this by creating a Windows Installer installation package to
create a new account that belongs to the local built-in administrators group or to install a malicious application. To
reduce this risk, all application installations should be strictly controlled.
The following Group Policy settings can be implemented to control application installations.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\File Explorer
Configure Windows Defender SmartScreen
Enabled
Pick one of the following settings: Warn and prevent
bypass
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender
SmartScreen\Explorer
Configure Windows Defender SmartScreen
Enabled
Pick one of the following settings: Warn and prevent
bypass
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Installer
Allow user control over installs
Disabled
Always install with elevated privileges
Disabled
User Configuration\Policies\Administrative Templates\Windows Components\Windows Installer
Always install with elevated privileges
Disabled
Internet printing
Microsoft Windows has the ability to print to internet printers over HTTP. If not disabled, this functionality could result
in the accidental or intentional release of sensitive information into the public domain. To reduce this risk, internet
printing should be disabled.
The following Group Policy settings can be implemented to prevent the use of internet printing.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Internet Communication Management\
Internet Communication settings
Turn off downloading of print drivers over HTTP
Enabled
Turn off printing over HTTP
Enabled
37
Legacy and run once lists
Once malicious code has been copied to a workstation, an adversary with registry access can remotely schedule it to
execute (i.e. using the run once list) or to automatically execute each time Microsoft Windows starts (i.e. using the
legacy run list). To reduce this risk, legacy and run once lists should be disabled. This may interfere with the operation
of legitimate applications that need to automatically execute each time Microsoft Windows starts. In such cases, the
Run these programs at user logon Group Policy setting can be used to perform the same function in a more secure
manner when defined at a domain level; however, if not used this Group Policy setting should be disabled rather than
left in its default undefined state.
The following Group Policy settings can be implemented to disable the use of legacy and run once lists.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Logon
Do not process the legacy run list
Enabled
Do not process the run once list
Enabled
Run these programs at user logon
Disabled
Microsoft accounts
A feature of Microsoft Windows 10 version 1709 is the ability to link Microsoft accounts (formerly Windows Live IDs) to
local or domain accounts. When this occurs, a user’s settings and files are stored in the cloud using OneDrive rather
than locally or on a domain controller. While this may have the benefit of allowing users to access their settings and
files from any workstation (e.g. corporate workstation, home PC, Internet café) it can also pose a risk to an organisation
as they lose control over where sensitive information may be accessed from. To reduce this risk, users should not link
Microsoft accounts with local or domain accounts.
The following Group Policy settings can be implemented to disable the ability to link Microsoft accounts to local or
domain accounts.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Microsoft account
Block all consumer Microsoft account user
authentication
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\OneDrive
Prevent the usage of OneDrive for file storage
Enabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Accounts: Block Microsoft accounts
Users can’t add or log on with Microsoft accounts
38
MSS settings
By failing to specify MSS specific registry values an adversary may be able to exploit weaknesses in a workstation’s
security posture to gain access to sensitive information. To reduce this risk, MSS specific registry values that are still
relevant to modern versions of Microsoft Windows should be specified using Group Policy settings.
The Group Policy Administrative Templates for MSS specific registry values are available from the Microsoft Security
Guidance blog28. The ADMX and ADML files can be placed in
%SystemDrive%\Windows\SYSVOL\domain\Policies\PolicyDefinitions on the Domain Controller and they will
automatically be loaded in the Group Policy Management Editor.
The following Group Policy settings can be implemented to configure MSS specific registry values that are still relevant
to modern versions of Microsoft Windows.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\MSS (Legacy)
MSS: (DisableIPSourceRouting IPv6) IP source routing
protection level (protects against packet spoofing)
Enabled
MSS: (DisableIPSourceRouting) IP source routing
protection level (protects against packet spoofing)
Enabled
MSS: (EnableICMPRedirect) Allow ICMP redirects to
override OSPF generated routes
Disabled
MSS: (NoNameReleaseOnDemand) Allow the computer
to ignore NetBIOS name release requests except from
WINS servers
Enabled
DisableIPSourceRoutingIPv6: Highest protection, source
routing is completely disabled
DisableIPSourceRouting: Highest protection, source
routing is completely disabled
NetBIOS over TCP/IP
NetBIOS over TCP/IP facilitates a number of intrusion methods. To reduce this risk, NetBIOS over TCP/IP should be
disabled. As NetBIOS over TCP/IP is only used to support legacy Microsoft Windows operating systems, such as those
prior to Microsoft Windows 2000, there shouldn’t be a business requirement for its use except in very rare
circumstances. NetBIOS over TCP/IP can be disabled by setting the NetBIOS settings under the IPv4 WINS settings on
each network interface to Disable NetBIOS over TCP/IP. NetBIOS over TCP/IP is not supported by IPv6.
Network authentication
Using insecure network authentication methods may permit an adversary to gain unauthorised access to network
traffic and services. To reduce this risk, only secure network authentication methods, ideally Kerberos, should be used
for network authentication.
28
https://blogs.technet.microsoft.com/secguide/2016/10/02/the-mss-settings/
39
The following Group Policy settings can be implemented to configure Kerberos, and if required for legacy purposes, the
use of NTLMv2.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Network security: Configure encryption types allowed
for Kerberos
AES128_HMAC_SHA1
Network security: LAN Manager authentication level
Send NTLMv2 response only. Refuse LM & NTLM
Network security: Minimum session security for NTLM
SSP based (including secure RPC) clients
Require NTLMv2 session security
Network security: Minimum session security for NTLM
SSP based (including secure RPC) servers
Require NTLMv2 session security
AES256_HMAC_SHA1
Require 128-bit encryption
Require 128-bit encryption
NoLMHash policy
When Microsoft Windows hashes a password that is less than 15 characters, it stores both a LAN Manager hash (LM
hash) and Windows NT hash (NT hash) in the local SAM database for local accounts, or in Activity Directory for domain
accounts. The LM hash is significantly weaker than the NT hash and can easily be brute forced. To reduce this risk, the
NoLMHash Policy should be implemented on all workstations and domain controllers. As the LM hash is designed for
authentication of legacy Microsoft Windows operating systems, such as those prior to Microsoft Windows 2000, there
shouldn’t be a business requirement for its use except in very rare circumstances.
The following Group Policy setting can be implemented to prevent the storage of LM hashes for passwords. All users
should be encouraged to change their password once this Group Policy setting has been set as until they do they will
remain vulnerable.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Network security: Do not store LAN Manager hash value
on next password change
Enabled
Operating system functionality
Leaving unneeded functionality in Microsoft Windows enabled can provide greater opportunities for potentially
vulnerable or misconfigured functionality to be exploited by an adversary. To reduce this risk, unneeded functionality in
Microsoft Windows should be disabled or removed.
Power management
One method of reducing power usage by workstations is to enter a sleep, hibernation or hybrid sleep state after a predefined period of inactivity. When a workstation enters a sleep state it maintains the contents of memory while
powering down the rest of the workstation; with hibernation or hybrid sleep, it writes the contents of memory to the
40
hard drive in a hibernation file (hiberfil.sys) and powers down the rest of the workstation. When this occurs, sensitive
information such as encryption keys could either be retained in memory or written to the hard drive in a hibernation
file. An adversary with physical access to the workstation and either the memory or hard drive can recover the sensitive
information using forensic techniques. To reduce this risk, sleep, hibernation and hybrid sleep states should be
disabled.
The following Group Policy settings can be implemented to ensure that sleep, hibernation and hybrid sleep states are
disabled.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Power Management\Sleep Settings
Allow standby states (S1-S3) when sleeping (on battery)
Disabled
Allow standby states (S1-S3) when sleeping (plugged in)
Disabled
Require a password when a computer wakes (on
battery)
Enabled
Require a password when a computer wakes (plugged in)
Enabled
Specify the system hibernate timeout (on battery)
Enabled
System Hibernate Timeout (seconds): 0
Specify the system hibernate timeout (plugged in)
Enabled
System Hibernate Timeout (seconds): 0
Specify the system sleep timeout (on battery)
Enabled
System Sleep Timeout (seconds): 0
Specify the system sleep timeout (plugged in)
Enabled
System Sleep Timeout (seconds): 0
Specify the unattended sleep timeout (on battery)
Enabled
Unattended Sleep Timeout (seconds): 0
Specify the unattended sleep timeout (plugged in)
Enabled
Unattended Sleep Timeout (seconds): 0
Turn off hybrid sleep (on battery)
Enabled
Turn off hybrid sleep (plugged in)
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\File Explorer
41
Show hibernate in the power options menu
Disabled
Show sleep in the power options menu
Disabled
PowerShell
Allowing any PowerShell script to execute exposes a workstation to the risk that a malicious script may be unwittingly
executed by a user. To reduce this risk, users should not have the ability to execute PowerShell scripts; however, if
using PowerShell scripts is an essential business requirement, only signed scripts should be allowed to execute.
Ensuring that only signed scripts are allowed to execute can provide a level of assurance that a script is trusted and has
been endorsed as having a legitimate business purpose.
For more information on how to effectively implement PowerShell see the Securing PowerShell in the Enterprise
publication29.
The following Group Policy settings can be implemented to control the use of PowerShell scripts.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows PowerShell
Turn on PowerShell Script Block Logging
Enabled
Turn on Script Execution
Enabled
Execution Policy: Allow only signed scripts
Registry editing tools
One method for malicious code to maintain persistence (i.e. remain after a workstation is rebooted) is to use
administrative privileges to modify the registry (as standard privileges only allow viewing of the registry). To reduce this
risk, users should not have the ability to modify the registry using registry editing tools (i.e. regedit) or to make silent
changes to the registry (i.e. using .reg files).
The following Group Policy setting can be implemented to prevent users from viewing or modifying the registry using
registry editing tools.
Group Policy Setting
Recommended Option
User Configuration\Policies\Administrative Templates\System
Prevent access to registry editing tools
Enabled
Disable regedit from running silently: Yes
Remote Assistance
While Remote Assistance can be a useful business tool to allow system administrators to remotely administer
workstations, it can also pose a risk. When a user has a problem with their workstation they can generate a Remote
Assistance invitation. This invitation authorises anyone that has access to it to remotely control the workstation that
29
https://www.acsc.gov.au/publications/protect/Securing_PowerShell.pdf
42
issued the invitation. Invitations can be sent by email, instant messaging or saved to a file. If an adversary manages to
intercept an invitation they will be able to use it to access the user’s workstation. Additionally, if network traffic on port
3389 is not blocked from reaching the Internet, users may send Remote Assistance invitations over the Internet which
could allow for remote access to their workstation by an adversary. While Remote Assistance only grants access to the
privileges of the user that generated the request, an adversary could install a key logging application on the workstation
in preparation of a system administer using their privileged credentials to fix any problems. To reduce this risk, Remote
Assistance should be disabled.
The following Group Policy settings can be implemented to disable Remote Assistance.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Remote Assistance
Configure Offer Remote Assistance
Disabled
Configure Solicited Remote Assistance
Disabled
Remote Desktop Services
While remote desktop access may be convenient for legitimate users to access workstations across a network, it also
allows an adversary to access other workstations once they have compromised an initial workstation and user’s
credentials. This risk can be compounded if an adversary can compromise domain administrator credentials or common
local administrator credentials. To reduce this risk, Remote Desktop Services should be disabled.
The following Group Policy settings can be implemented to disable Remote Desktop Services.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\
Remote Desktop Session Host\Connections
Allow users to connect remotely by using Remote
Desktop Services
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Allow log on through Remote Desktop Services
<blank>
Deny log on through Remote Desktop Services
Administrators
Guests
NT AUTHORITY\Local Account
Alternatively, if it is an essential business requirement to use Remote Desktop Services, it should be configured in a
manner that is as secure as possible and only on workstations and for users for which it is explicitly required.
The following Group Policy settings can be implemented to use Remote Desktop Services in as secure a manner as
possible.
43
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Credentials Delegation
Remote host allows delegation of non-exportable
credentials
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\
Remote Desktop Connection Client
Configure server authentication for client
Enabled
Authentication setting:
Do not connect if authentication fails
Do not allow passwords to be saved
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\
Remote Desktop Session Host\Connections
Allow users to connect remotely by using Remote
Desktop Services
Enabled
Deny logoff of an administrator logged in to the console
session
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\
Remote Desktop Session Host\Device and Resource Redirection
Do not allow Clipboard redirection
Enabled
Do not allow drive redirection
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Remote Desktop Services\
Remote Desktop Session Host\Security
Always prompt for password upon connection
Enabled
Do not allow local administrators to customize
permissions
Enabled
Require secure RPC communication
Enabled
Require use of specific security layer for remote (RDP)
connections
Enabled
Security Layer: SSL
44
Require user authentication for remote connections by
using Network Level Authentication
Enabled
Set client connection encryption level
Enabled
Encryption Level: High Level
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Allow log on through Remote Desktop Services
Remote Desktop Users
Deny log on through Remote Desktop Services
Administrators
Guests
Remote Procedure Call
Remote Procedure Call (RPC) is a technique used for facilitating client and server application communications using a
common interface. RPC is designed to make client and server interaction easier and safer by using a common library to
handle tasks such as security, synchronisation and data flows. If unauthenticated communications are allowed between
client and server applications, it could result in accidental disclosure of sensitive information or the failure to take
advantage of RPC security functionality. To reduce this risk, all RPC clients should authenticate to RPC servers.
The following Group Policy setting can be implemented to ensure RPC clients authenticate to RPC servers.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Remote Procedure Call
Restrict Unauthenticated RPC clients
Enabled
RPC Runtime Unauthenticated Client Restriction to
Apply: Authenticated
Reporting system information
Microsoft Windows contains a number of in-built functions to, often automatically and transparently, report system
information to Microsoft. This includes system errors and crash information as well as inventories of applications, files,
devices and drivers on the system. If captured by an adversary, this information could expose potentially sensitive
information on workstations. This information could also subsequently be used by an adversary to tailor malicious code
to target specific workstations or users. To reduce this risk, all in-built functions that report potentially sensitive system
information should be directed to a corporate Windows Error Reporting server.
The following Group Policy settings can be implemented to prevent potentially sensitive system information being
reported to Microsoft.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Troubleshooting and Diagnostics\Microsoft
Support Diagnostic Tool
45
Microsoft Support Diagnostic Tool: Turn on MSDT
interactive communication with support provider
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Application Compatibility
Turn off Inventory Collector
Enabled
Turn off Steps Recorder
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Data Collection and Preview
Builds
Allow Telemetry
Enabled
0 - Security [Enterprise Only]
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Error Reporting\
Advanced Error Reporting Settings
Configure Corporate Windows Error Reporting
Enabled
Corporate server name: <organisation defined>
Connect using SSL
Server port: <organisation defined>
Safe Mode
An adversary with standard user credentials that can boot into Microsoft Windows using Safe Mode, Safe Mode with
Networking or Safe Mode with Command Prompt options may be able to bypass system protections and security
functionality such as application whitelisting solutions. To reduce this risk, users with standard credentials should be
prevented from using Safe Mode options to log in.
The following registry entry can be implemented using Group Policy preferences to prevent non-administrators from
using Safe Mode options.
Registry Entry
Recommended Value
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
SafeModeBlockNonAdmins
REG_DWORD 0x00000001 (1)
Secure channel communications
Periodically, workstations connected to a domain will communicate with the domain controllers. If an adversary has
access to unprotected network communications they may be able to capture or modify sensitive information
communicated between workstations and the domain controllers. To reduce this risk, all secure channel
communications should be signed and encrypted with strong session keys.
The following Group Policy settings can be implemented to ensure secure channel communications are appropriately
signed and encrypted.
46
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Domain member: Digitally encrypt or sign secure
channel data (always)
Enabled
Domain member: Digitally encrypt secure channel data
(when possible)
Enabled
Domain member: Digitally sign secure channel data
(when possible)
Enabled
Domain member: Require strong (Windows 2000 or
later) session key
Enabled
Security policies
By failing to comprehensively specify security policies, an adversary may be able to exploit weaknesses in a
workstation’s Group Policy settings to gain access to sensitive information. To reduce this risk, security policies should
be comprehensively specified.
The following Group Policy settings can be implemented, in addition to those specifically mentioned in other areas of
this document, to form a comprehensive set of security policies.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Network\DNS Client
Turn off multicast name resolution
Enabled
Computer Configuration\Policies\Administrative Templates\Network\WLAN Service\WLAN Settings
Allow Windows to automatically connect to suggested
open hotspots, to networks shared by contacts, and to
hotspots offering paid services
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Cloud Content
Turn off Microsoft consumer experiences
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\File Explorer
Turn off heap termination on corruption
Disabled
Turn off shell protocol protected mode
Disabled
47
Computer Configuration\Policies\Administrative Templates\Windows Components\RSS Feeds
Prevent downloading of enclosures
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Search
Allow indexing of encrypted files
Disabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Game Recording
and Broadcasting
Enables or disables Windows Game Recording and
Broadcasting
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Domain member: Disable machine account password
changes
Disabled
Domain member: Maximum machine account password
age
30 days
Network security: Allow PKU2U authentication requests
to this computer to use online identities.
Disabled
Network security: Force logoff when logon hours expire
Enabled
Network security: LDAP client signing requirements
Negotiate signing
System objects: Require case insensitivity for nonWindows subsystems
Enabled
System objects: Strengthen default permissions of
internal system objects (e.g. Symbolic Links)
Enabled
Server Message Block sessions
An adversary that has access to network communications may attempt to use session hijacking tools to interrupt,
terminate or steal a Server Message Block (SMB) session. This could potentially allow an adversary to modify packets
and forward them to a SMB server to perform undesirable actions or to pose as the server or client after a legitimate
authentication has taken place to gain access to sensitive information. To reduce this risk, all communications between
SMB clients and servers should be signed, with any passwords used appropriately encrypted.
The following Group Policy settings can be implemented to ensure communications between SMB clients and servers
are secure.
48
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\MS Security Guide
Configure SMB v1 client driver
Enabled
Configure MrxSmb10 driver: Disable driver
(recommended)
Configure SMB v1 server
Disabled
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
Microsoft network client: Digitally sign communications
(always)
Enabled
Microsoft network client: Digitally sign communications
(if server agrees)
Enabled
Microsoft network client: Send unencrypted password to
third-party SMB servers
Disabled
Microsoft network server: Amount of idle time required
before suspending session
15 minutes
Microsoft network server: Digitally sign communications
(always)
Enabled
Microsoft network server: Digitally sign communications
(if client agrees)
Enabled
Session locking
An adversary with physical access to an unattended workstation may attempt to inappropriately access other users’
sessions in order to use their credentials to access sensitive information they don’t have access to or to conduct actions
on the network that won’t be attributed to them. To reduce this risk, a session lock should be configured to activate
after a maximum of 15 minutes of user inactivity.
The following Group Policy settings can be implemented to set session locks.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Control Panel\Personalization
Prevent enabling lock screen camera
Enabled
Prevent enabling lock screen slide show
Enabled
49
Computer Configuration\Policies\Administrative Templates\System\Logon
Allow users to select when a password is required when
resuming from connected standby
Disabled
Turn off app notifications on the lock screen
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\File Explorer
Show lock in the user tile menu
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Ink Workspace
Allow Windows Ink Workspace
Enabled
Choose one of the following actions: On, but disallow
access above lock
Computer Configuration\Policies\Windows Settings\Local Policies\Security Options
Interactive logon: Machine inactivity limit
900 seconds
User Configuration\Policies\Administrative Templates\Control Panel\Personalization
Enable screen saver
Enabled
Password protect the screen saver
Enabled
Screen saver timeout
Enabled
Seconds: 900
User Configuration\Policies\Administrative Templates\Start Menu and Taskbar\Notifications
Turn off toast notifications on the lock screen
Enabled
User Configuration\Policies\Administrative Templates\Windows Components\Cloud Content
Do not suggest third-party content in Windows spotlight
Enabled
Software-based firewalls
Network firewalls often fail to prevent the propagation of malicious code on a network, or an adversary from extracting
sensitive information, as they generally only control which ports or protocols can be used between segments on a
network. Many forms of malicious code are designed specifically to take advantage of this by using common protocols
such as HTTP, HTTPS, SMTP and DNS. To reduce this risk, software-based firewalls that filter both incoming and
outgoing traffic should be appropriately implemented. Software-based firewalls are more effective than network
50
firewalls as they can control which applications and services can communicate to and from workstations. The in-built
Windows firewall30 can be used to control both inbound and outbound traffic for specific applications.
Sound Recorder
Sound Recorder is a feature of Microsoft Windows that allows audio from a device with a microphone to be recorded
and saved as an audio file on the local hard drive. An adversary with remote access to a workstation can use this
functionality to record sensitive conversations in the vicinity of the workstation. To reduce this risk, Sound Recorder
should be disabled.
The following Group Policy setting can be implemented to disable the use of Sound Recorder.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Sound Recorder
Do not allow Sound Recorder to run
Enabled
Standard Operating Environment
When users are left to setup, configure and maintain their own workstations it can very easily lead to an inconsistent
and insecure environment where particular workstations are more vulnerable than others. This inconsistent and
insecure environment can easily allow an adversary to gain an initial foothold on a network. To reduce this risk,
workstations should connect to a domain using a Standard Operating Environment that is centrally controlled and
configured by experienced information technology and information security professionals.
System backup and restore
An adversary that compromises a user account with privileges to backup files and directories can use this privilege to
backup the contents of a workstation. This content can then be transferred to a non-domain connected workstation
where the adversary has administrative access. From here an adversary can restore the contents and take ownership,
thereby circumventing all original access controls that were in place. In addition, if a user has privileges to restore files
and directories, an adversary could exploit this privilege by using it to either restore previous versions of files that may
have been removed by system administrators as part of malicious code removal activities or to replace existing files
with malicious variants. To reduce this risk, the ability to use backup and restore functionality should be limited to
administrators.
The following Group Policy settings can be implemented to control the use of backup and restore functionality.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Back up files and directories
Administrators
Restore files and directories
Administrators
30
https://docs.microsoft.com/en-au/windows/security/threat-protection/windows-firewall/windows-firewall-withadvanced-security
51
System cryptography
By default, when cryptographic keys are stored in Microsoft Windows, users can access them without first entering a
password to unlock the certificate store. An adversary that compromises a workstation, or gains physical access to an
unlocked workstation, can use these user keys to access sensitive information or resources that are cryptographically
protected. To reduce this risk, strong encryption algorithms and strong key protection should be used on workstations.
The following Group Policy settings can be implemented to ensure strong encryption algorithms and strong key
protection is used.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
System cryptography: Force strong key protection for
user keys stored on the computer
User must enter a password each time they use a key
System cryptography: Use FIPS compliant algorithms for
encryption, hashing, and signing
Enabled
User rights policies
By failing to comprehensively specify user rights policies, an adversary may be able to exploit weaknesses in a
workstation’s Group Policy settings to gain access to sensitive information. To reduce this risk, user rights policies
should be comprehensively specified.
The following Group Policy settings can be implemented, in addition to those specifically mentioned in other areas of
this document, to form a comprehensive set of user rights policies.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\User Rights Assignment
Access Credential Manager as a trusted caller
<blank>
Act as part of the operating system
<blank>
Allow log on locally
Administrators
Users
Create a pagefile
Administrators
Create a token object
<blank>
Create global objects
Administrators
LOCAL SERVICE
NETWORK SERVICE
SERVICE
52
Create permanent shared objects
<blank>
Create symbolic links
Administrators
Debug programs
Administrators
Enable computer and user accounts to be trusted for
delegation
<blank>
Force shutdown from a remote system
Administrators
Impersonate a client after authentication
Administrators
LOCAL SERVICE
NETWORK SERVICE
SERVICE
Increase scheduling priority
Administrators
Load and unload device drivers
Administrators
Lock pages in memory
<blank>
Modify an object label
<blank>
Modify firmware environment values
Administrators
Perform volume maintenance tasks
Administrators
Profile single process
Administrators
Take ownership of files or other objects
Administrators
Virtualised web and email access
An adversary can often deliver malicious code directly to workstations via external web and email access. Once a
workstation has been exploited, an adversary can use these same communication paths for bi-directional
communications to control their malicious code. To reduce this risk, web and email access on workstations should occur
through a non-persistent virtual environment (i.e. using virtual desktops or virtual applications). When using a virtual
environment, workstations will receive additional protection against intrusion attempts targeted at exploiting security
vulnerabilities in web browsers and email clients as any attempts, if successful, will execute in a non-persistent virtual
environment rather than on a local workstation.
Web Proxy Auto Discovery protocol
The Web Proxy Auto Discovery (WPAD) protocol assists with the automatic detection of proxy settings for web
browsers. Unfortunately, WPAD has suffered from a number of severe security vulnerabilities. Organisations that do
53
not rely on the use of the WPAD protocol should disable it. This can be achieved by modifying each workstation’s host
file at %SystemDrive%\Windows\System32\Drivers\etc\hosts to create the following entry: 255.255.255.255 wpad.
Windows Remote Management
Windows Remote Management (WinRM)31 is the Microsoft implementation of the WS-Management Protocol32 which
was developed as a public standard for remotely exchanging management data between devices that implement the
protocol. If appropriate authentication and encryption is not implemented for this protocol, traffic may be subject to
inception by an adversary. To reduce this risk, Windows Remote Management should be securely configured.
The following Group Policy settings can be implemented to secure the use of the Windows Remote Management.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Remote
Management (WinRM)\WinRM Client
Allow Basic authentication
Disabled
Allow unencrypted traffic
Disabled
Disallow Digest authentication
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Remote
Management (WinRM)\WinRM Service
Allow Basic authentication
Disabled
Allow unencrypted traffic
Disabled
Disallow WinRM from storing RunAs credentials
Enabled
Windows Remote Shell access
When Windows Remote Shell is enabled it can allow an adversary to remotely execute scripts and commands on
workstations. To reduce this risk, Windows Remote Shell should be disabled.
The following Group Policy setting can be implemented to disable Windows Remote Shell access.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Remote Shell
Allow Remote Shell Access
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Disabled
https://msdn.microsoft.com/en-au/library/aa384426(v=vs.85).aspx
https://msdn.microsoft.com/en-au/library/windows/desktop/aa384470(v=vs.85).aspx
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Windows Search and Cortana
As part of the in-built search functionality of Microsoft Windows, users can search for Web results in addition to local
workstation results. This functionality if used could result in the accidental disclosure of sensitive information if
sensitive terms are searched for automatically on the Web in addition to the local workstation. To reduce this risk, the
ability to automatically search the Web should be disabled.
The following Group Policy settings can be implemented to prevent Web search results being returned for any user
search terms.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Search
Allow Cortana
Disabled
Don’t search the web or display web results in Search
Enabled
Windows To Go
A feature of Microsoft Windows 10 version 1709 is Windows To Go. Windows To Go allows users to boot into a
workspace stored on USB media from any machine that supports the minimum hardware requirements. While this may
be highly beneficial for Bring Your Own Device (BYOD) or remote access initiatives, it can also pose a risk to an
organisation’s network. Workstations that allow automatic booting of Windows To Go workspaces do not discriminate
between approved workspaces and malicious workspaces developed by an adversary. As such, an adversary may use a
malicious workspace they have customised with their desired toolkit to attempt to gain access to sensitive information
on the network. To reduce this risk, automatic booting of Windows To Go media should be disabled.
The following Group Policy setting can be implemented to disable the automatic booting of Windows To Go media.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Portable Operating System
Windows To Go Default Startup Options
Disabled
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Low priorities
The following security controls, listed in alphabetical order, are recommended for consideration and should be treated
as low priorities when hardening Microsoft Windows 10 version 1709 workstations.
Displaying file extensions
When extensions for known file types are hidden, an adversary can more easily use social engineering techniques to
convince users to execute malicious email attachments. For example, a file named vulnerability_assessment.pdf.exe
could appear as vulnerability_assessment.pdf to a user. To reduce this risk, hiding extensions for known file types
should be disabled. Showing extensions for all known file types, in combination with user education and awareness of
dangerous email attachment file types, can help reduce the risk of users executing malicious email attachments.
The following registry entry can be implemented using Group Policy preferences to prevent extensions for known file
types from being hidden.
Registry Entry
Recommended Value
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
HideFileExt
REG_DWORD 0x00000000 (0)
File and folder security properties
By default, all users have the ability to view security properties of files and folders. This includes the security properties
associated with files and folders as well as users and groups that they relate to. An adversary could use this information
to target specific accounts that have access to sensitive information. To reduce this risk, users should not have the
ability to view security properties of files and folders.
The following Group Policy setting can be implemented to disable users’ access to the security tab in file and folder
properties in File Explorer.
Group Policy Setting
Recommended Option
User Configuration\Policies\Administrative Templates\Windows Components\File Explorer
Remove Security tab
Enabled
Location awareness
When users interact with the Internet their workstations often automatically provide geo-location details to websites
or online services to assist them in tailoring content specific to the user’s geographical region (i.e. the city they are
accessing the Internet from). This information can be captured by an adversary to determine the location of a specific
user. To reduce this risk, location services in the operating system and applications should be disabled.
The following Group Policy settings can be implemented to disable location services within the operating system.
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Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\Windows Components\Location and Sensors
Turn off location
Enabled
Turn off location scripting
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Location and Sensors\
Windows Location Provider
Turn off Windows Location Provider
Enabled
Microsoft Store
Whilst applications in the Microsoft Store are vetted by Microsoft, there is still a risk that users given access to the
Microsoft Store could download and install potentially malicious applications or applications that cause conflicts with
other endorsed applications on their workstation. To reduce this risk, access to the Microsoft Store should be disabled.
The following Group Policy settings can be implemented to prevent Microsoft Store access.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Internet Communication Management\
Internet Communication settings
Turn off access to the Store
Enabled
Computer Configuration\Policies\Administrative Templates\Windows Components\Store
Turn off the Store application
Enabled
Publishing information to the Web
Microsoft Windows has the ability to assist users in either directly publishing information to the Web or sending
information to publishers for professional publication. If not disabled, this functionality could result in the accidental or
intentional release of sensitive information into the public domain. To reduce this risk, the ability to publish information
to the Web or send to publishers should be disabled.
The following Group Policy setting can be implemented to disable the ability to publish information to the Web or send
it to publishers.
Group Policy Setting
Recommended Option
Computer Configuration\Policies\Administrative Templates\System\Internet Communication Management\
Internet Communication settings
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Turn off Internet download for Web publishing and
online ordering wizards
Enabled
Resultant Set of Policy reporting
By default, all users have the ability to generate Resultant Set of Policy (RSOP) reports which allows them to view the
Group Policy settings being applied to their workstation and user account. This information could be used by an
adversary to determine misconfigurations or weaknesses in Group Policy settings being applied to the workstation or
the user account. To reduce this risk, users should not have the ability to generate RSOP reports.
The following Group Policy setting can be implemented to disable users’ ability to generate RSOP reports.
Group Policy Setting
Recommended Option
User Configuration\Policies\Administrative Templates\System\Group Policy
Determine if interactive users can generate Resultant Set
of Policy data
Enabled
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Contact details
Organisations or individuals with questions regarding this advice can contact the ACSC by emailing
asd.assist@defence.gov.au or calling 1300 CYBER1 (1300 292 371).
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