APRIL 2015
Cloud Computing Security
for Cloud Service Providers
Introduction
1. This document is designed to assist assessors 1 validating the security posture of a cloud service in order to provide
organisations with independent assurance of security claims made by Cloud Service Providers (CSPs). This document
can also assist CSPs to offer secure cloud services.
2. An organisation’s cyber security team, cloud architects and business representatives should refer to the companion
document Cloud Computing Security for Tenants 2.
3. Cloud computing, as defined by the U.S. National Institute of Standards and Technology3, offers organisations potential
benefits such as improved business outcomes.
4. Mitigating the risks associated with using cloud services is a responsibility shared between the organisation (referred to
as the ‘tenant’) and the Cloud Service Provider, including their subcontractors (referred to as the ‘CSP’). However,
organisations are ultimately responsible for protecting their data and ensuring its confidentiality, integrity and
availability.
5. Organisations need to perform a risk assessment 4 and implement associated mitigations before using cloud services.
Risks vary depending on factors such as the sensitivity and criticality of data to be stored or processed, how the cloud
service is implemented and managed, how the organisation intends to use the cloud service, and challenges associated
with the organisation performing timely incident detection and response. Organisations need to compare these risks
against an objective risk assessment of using in-house computer systems which might be poorly secured, have
inadequate availability or be unable to meet modern business requirements.
6. The scope of this document covers Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a
Service (SaaS), provided by a CSP as part of a public cloud, community cloud and, to a lesser extent, a hybrid cloud or
outsourced private cloud.
7. This document focuses on the use of cloud services for storing or processing sensitive and highly sensitive data. For
Commonwealth entities, and for the purposes of this document, sensitive data is defined as unclassified data with a dissemination limiting marker (DLM), such as For Official Use Only (FOUO) orFICIAL: Sensitive: Personal (which aligns with the definition of sensitive information in the Privacy Act 19885). Highly
sensitive data is defined as data classified as PROTECTED. Additionally, this document can assist with mitigating risks to
the availability and integrity of non-sensitive data, defined for Commonwealth entities as unclassified publicly
releasable data. Mitigations are listed in no particular order of prioritisation.
Page 1 of 4
Cloud Computing Security for Cloud Service Providers
Reference Number
Mitigations
APRIL 2015
Most Effective Risk Mitigations- Generally Relevant to All Types of Cloud Services: Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS)
Overarching failure to maintain the confidentiality, integrity and availability of the tenant’s data
1 - General Obtain certification15 of the cloud service and underlying infrastructure (explicitly addressing mitigations in this document) against the ISM6 at the appropriate classification level required to handle the tenant’s data.
2 - General
Implement security governance involving senior management directing and coordinating security-related activities including robust change management, as well as having technically skilled staff in defined security roles.
3 - General
Implement and annually test an incident response plan providing the tenant with emergency contact details, the ability to access forensic evidence otherwise inaccessible to the tenant, and contractual notification of incidents.
Tenant’s data compromised in transit by malicious third party Tenant’s cloud service account credentials compromised by malicious third party7 8 9 10
4 - General
Support and use ASD-approved cryptographic controls to protect data in transit between the tenant and the CSP e.g. application layer TLS or IPsec VPN with approved algorithms, key length and key management.
5 - General
Use ASD-approved cryptographic controls to protect data in transit between the CSP’s data centres over insecure communication channels such as public Internet infrastructure.
6 - General
Support and use ASD-approved cryptographic controls to protect data at rest on storage media in transit via post/courier between the tenant and the CSP when transferring data as part of on-boarding or off-boarding.
7 - General
Provide Identity and Access Management e.g. multi-factor authentication and account roles with varying privileges11 for the tenant to use and administer the cloud service via the CSP’s website control panel and API.
8 - General
Support and use ASD-approved cryptographic controls to protect credentials and administrative activity in transit when the tenant uses and administers the cloud service via the CSP’s website control panel and API.
9 - General
Enable the tenant to download detailed time-synchronised logs and obtain real-time alerts generated for the tenant’s cloud service accounts used to access, and especially to administer, the cloud service.
Tenant’s data compromised by malicious CSP staff or malicious third party
10 - General
Enable the tenant to download detailed time-synchronised logs and obtain real-time alerts generated by the cloud service used by the tenant e.g. operating system, web server and application logs.
11 - General
Disclose the countries and legal jurisdictions where tenant data is (or will be in the coming months) stored, backed up, processed12 and accessed by CSP staff for troubleshooting, remote administration and customer support.
12 - General
Perform background checks of CSP staff commensurate with their level of access to systems and data. Maintain security clearances for staff with access to highly sensitive data13.
13 - General
Use physically secure data centres and offices that store tenant data or that can access tenant data14. Verify and record the identity of all staff and visitors. Escort visitors to mitigate them accessing data without authorisation.
14 - General
Restrict CSP staff privileged access to systems and data based on their job tasks115. Require re-approval every three months for CSP staff requiring privileged access. Revoke access upon termination of CSP staff employment.
15 - General
Promptly analyse logs of CSP staff actions that are logged to a secured and isolated log server. Implement separation of duties by requiring log analysis to be performed by CSP staff who have no other privileges or job roles.
16 - General
Perform a due diligence review of suppliers before obtaining software, hardware or services, to assess the potential increase to the CSP’s security risk profile.
17 - General
Use ASD-approved cryptographic controls to protect highly sensitive data at rest. Sanitise storage media prior to repair, disposal, and tenant off-boarding with a non-disclosure agreement for data in residual backups.
Tenant’s data compromised by another malicious/compromised tenant15 16 17 18 19 20 21 22 23 24 18 - General
Implement multi-tenancy mechanisms to prevent the tenant’s data being accessed by other tenants. Isolate network traffic, storage, memory and computer processing. Sanitise storage media prior to its reuse.
Tenant’s data unavailable due to corruption, deletion8, or CSP terminating the account/service 19 - General
Enable the tenant to perform up-to-date backups in a format that avoids CSP lock-in. If an account or cloud service is terminated, immediately notify the tenant and provide them with at least a month to download their data.
Tenant’s data unavailable or compromised due to CSP bankruptcy or other legal action
20 - General
Contractually ensure that the tenant retains legal ownership of their data.
Cloud service unavailable due to CSP’s inadequate network connectivity
21 - General
Support adequately high bandwidth, low latency, reliable network connectivity between the tenant and the cloud service to meet the claimed level of availability as required by the tenant.
Cloud service unavailable due to CSP error, planned outage, failed hardware or act of nature
22 - General
Architect to meet the claimed level of availability as required by the tenant e.g. minimal single points of failure, clustering and load balancing, data replication, automated failover and real-time availability monitoring.
23 - General
Develop and annually test a disaster recovery and business continuity plan to meet the claimed level of availability as required by the tenant, e.g. enacted for incidents that cause enduring loss of CSP staff or infrastructure.
24 - General
Implement denial of service mitigations to meet the claimed level of availability as required by the tenant e.g. redundant high bandwidth external and internal network connectivity with traffic throttling and filtering.
Cloud service unavailable due to genuine spike in demand or bandwidth/CPU denial of service
25 - General
Provide infrastructure capacity and responsive automated scaling to meet the claimed level of availability as required by the tenant.
Financial consequences of a genuine spike in demand or bandwidth/CPU denial of service
26 - General
Enable the tenant to manage the cost of a genuine spike in demand or denial of service via contractual spending limits, real-time alerts, and configurable maximum limits for their use of the CSP’s infrastructure capacity.
CSP’s infrastructure compromised by malicious tenant or malicious third party
27 - General
Use corporately approved and secured computers, jump servers, dedicated accounts, strong passphrases and multi-factor authentication, to provide customer support and administer cloud services and infrastructure.
28 - General
Use ASD-approved cryptographic controls to protect credentials and administrative activity in transit over insecure communication channels between the CSP’s data centre and CSP administrator / customer support staff.
29 - General
Implement network segmentation and segregation257 between the Internet, CSP infrastructure used by tenants, the network that the CSP uses to administer cloud services and infrastructure, and the CSP’s corporate LAN.
30 - General
Utilise secure programming practices for software developed by the CSP268 279 2830.
31 - General
Perform secure configuration, ongoing vulnerability management, prompt patching, annual third party security reviews and penetration testing of cloud services and underlying infrastructure.
32 - General
Train all CSP staff, especially administrators, on commencement of employment and annually, to protect tenant data, maintain cloud service availability, and proactively identify security incidents e.g. via prompt log analysis.
Most Effective Risk Mitigations Particularly Relevant to IaaS
Tenant’s Virtual Machine (VM) compromised by malicious third party7
1 - IaaS 2 - IaaS
Provide network access controls enabling the tenant to implement network segmentation and segregation325, including a network filtering capability to disallow remote administration of their VMs except from their IP address.
2 - IaaS
Provide the tenant with securely configured and patched VM template images. Avoid assigning a weak administrative passphrase to newly provisioned VMs.
Most1 Effective Risk Mitigations Particularly Relevant to- PaaS
Tenant’s data compromised by malicious third party
1 - PaaS
Most Effective Risk Mitigations Particularly Relevant to SaaS
Tenant’s data compromised by malicious third party
1 - SaaS 2 - SaaS
Implement security controls specific to the cloud service e.g. for email delivered as a service, provide features including whitelisted content filtering with automated dynamic analysis of emails and email attachments.
2 - SaaS
Implement general security controls2933 e.g. limited inbound and outbound network connectivity to only required ports/protocols, antivirus software updated daily, intrusion prevention systems and prompt log analysis.
PMost Effective Risk Mitigations Generally Relevant to All Types of Cloud Services
Overarching failure 2to maintain the confidentiality, integrity and availability of the tenant’s data
Tenant’s data compromised in transit by malicious third party
Tenant’s cloud service account credentials compromised by malicious third
party7 8 9 10
Tenant’s data compromised by malicious CSP staff or malicious third party
Tenant’s data compromised by another malicious/compromised
Tenant’s data unavailable due to corruption,
deletion26,
tenant16 17 18 19 20 21 22 23 24 25
or CSP terminating the account/service
Cloud service unavailable due to genuine spike in demand or bandwidth/CPU denial of service
Most Effective Risk Mitigations Particularly Relevant to IaaS
Tenant’s Virtual Machine (VM) compromised by malicious third party31
Most Effective Risk Mitigations Particularly Relevant to PaaS
Tenant’s data compromised by malicious third party
Most Effective Risk Mitigations Particularly Relevant to SaaS
Tenant’s data compromised by malicious third party
2
Further information
8. The Australian Government Information Security Manual (ISM)634 provides guidance for mitigations such as ASD-approved cryptographic controls. The Strategies to Mitigate Cyber Security Incidents29 35provide additional guidance
for mitigations such as prompt patching, prompt log analysis, securing computers, as well as network segmentation and
segregation.
9. Commonwealth entities applying the ISM must only use outsourced cloud services listed on the Australian Cyber
Security Centre’s Certified Cloud Services List (CCSL)306. Commonwealth entities need to perform accreditation
activities, including reviewing the certification report, to determine whether the residual risk of their proposed use of a
cloud service is acceptable. Commonwealth entities also need to perform an additional due diligence review of
financial, privacy, data ownership, data sovereignty and legal risks 317.
10. Additional cloud computing security advice is available at https://www.acsc.gov.au/infosec/cloudsecurity.htm.
Contact details
11. 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).
1 https://www.acsc.gov.au/infosec/irap.htm 2
https://www.acsc.gov.au/infosec/cloudsecurity.htm
3 https://csrc.nist.gov/publications/detail/sp/800-145/final
4 https://www.protectivesecurity.gov.au/infgovermnationce/security/Documents/Austra-plianGovernmentInformationSecug-rityMsk-manageme ntGui/Pages/defaulinet.as.pdf x
5
https://www.oaicsc.gov.au/individuals/privacy-fact-osheetsc/geneiral/privacy-fact-s.heet-17-australian-privacy-principles m
6
https://www.acsc.gov.au/infosec/ism/
7 https://www.browserstack.com/attack-and-downtime-on-9-November
8 https://www.darkreading.com/attacks-breaches/code-hosting-service-shuts-down-after-cyber-attack/d/d-id/1278743
9 https://securosis.com/blog/my-500-cloud-security-screwup
10 https://www.theregister.co.uk/2014/05/20/github_oversharing_snafu_nbc_private_keys/
11 https://www.acsc.gov.au/publications/protect/Restricting_Admin_Privileges.pdf
12 https://news.defence.gov.au/media/media-releases/defence-optometry-contract-cancelled
13 https://www.protectivesecurity.gov.au/personnelsecurity/Pages/default.aspx
14 hhttps://www.protectivesecurity.gov.au/physicalsecurity/Pages/default.aspx
15
https://www.acsc.gov.au/publications/protect/Restricting_Admin_Privileges.pdf
16 https://www.cvedetails.com/vulnerability-list.php?vendor_id=252&product_id=22134&page=1&order=3
167 https://docs.microsoft.com/en-au/security-updates/SecurityBulletins/2013/ms13-092
178 https://www.cvedetails.com/vulnerability-list.php?vendor_id=6276&page=1&order=3
189 https://access.redhat.com/errata/RHSA-2014:0420
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1920 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-0311
20 1
https://blog.docker.com/2014/06/docker-container-breakout-proof-of-concept-exploit/
212 https://opensource.com/business/14/7/docker-security-selinux
223 https://www.theregister.co.uk/2014/11/25/docker_vulnerabilities/
234 https://www.theregister.co.uk/2014/12/12/docker_vulnerability/
245 https://seclists.org/fulldisclosure/2014/Dec/26
26
https://www.darkreading.com/attacks-breaches/code-hosting-service-shuts-down-after-cyber-attack/d/did/1278743
257 https://www.acsc.gov.au/publications/protect/Network_Segmentation_Segregation.pdf
268 https://www.microsoft.com/en-us/sdl
279 https://www.sans.org/top25-software-errors
1
28
3
https://www.owasp.org/index.php/OWASP_Proactive_Controls 2
https://www.browserstack.com/attack-and-downtime-on-9 -November
32
https://www.acsc.gov.au/publications/protect/Network_Segmentation_Segregation.pdf
33
https://www.acsc.gov.au/infosec/top35mitigationstrategies.htm
34
https://www.acsc.gov.au/infosec/ism/
305
https://www.acsc.gov.au/infosec/top35mitigationstrategies.htm
36 https://www.acsc.gov.au/infosec/irap/certified_clouds.htm
317 https://www.finance.gov.au/archive/cloud/
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