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Most Effective Risk Mitigations Generally Relevant to All Types of Cloud Services
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Overarching failure to maintain the confidentiality, integrity and availability of the tenant’s data
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1 - General
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Obtain certification [5] of the cloud service and underlying infrastructure (explicitly addressing mitigations in this document) against the ISM [6] at the appropriate classification level required to handle the tenant’s data.
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2 - General
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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.
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3 - General
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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.
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Tenant’s data compromised in transit by malicious third party
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4 - General
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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.
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5 - General
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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.
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6 - General
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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.
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Tenant’s cloud service account credentials compromised by malicious third party [7] [8] [9] [10]
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7 - General
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Provide Identity and Access Management e.g. multi-factor authentication and account roles with varying privileges [11] for the tenant to use and administer the cloud service via the CSP’s website control panel and API.
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8 - General
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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.
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9 - General
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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.
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Tenant’s data compromised by malicious CSP staff or malicious third party
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10 - General
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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.
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11 - General
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Disclose the countries and legal jurisdictions where tenant data is (or will be in the coming months) stored, backed up, processed [12] and accessed by CSP staff for troubleshooting, remote administration and customer support.
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12 - General
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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 data [13].
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13 - General
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Use physically secure data centres and offices that store tenant data or that can access tenant data [14]. Verify and record the identity of all staff and visitors. Escort visitors to mitigate them accessing data without authorisation.
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14 - General
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Restrict CSP staff privileged access to systems and data based on their job tasks [15]. Require re-approval every three months for CSP staff requiring privileged access. Revoke access upon termination of CSP staff employment.
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15 - General
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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.
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16 - General
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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.
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17 - General
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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.
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Tenant’s data compromised by another malicious/compromised tenant [16] [17] [18] [19] [20] [21] [22] [23] [24] [25]
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18 - General
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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.
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Tenant’s data unavailable due to corruption, deletion [26], or CSP terminating the account/service
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19 - General
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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.
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Tenant’s data unavailable or compromised due to CSP bankruptcy or other legal action
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20 - General
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Contractually ensure that the tenant retains legal ownership of their data.
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Cloud service unavailable due to CSP’s inadequate network connectivity
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21 - General
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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.
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Cloud service unavailable due to CSP error, planned outage, failed hardware or act of nature
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22 - General
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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.
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23 - General
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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.
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Cloud service unavailable due to genuine spike in demand or bandwidth/CPU denial of service
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24 - General
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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.
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25 - General
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Provide infrastructure capacity and responsive automated scaling to meet the claimed level of availability as required by the tenant.
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Financial consequences of a genuine spike in demand or bandwidth/CPU denial of service
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26 - General
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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.
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CSP’s infrastructure compromised by malicious tenant or malicious third party
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27 - General
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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.
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28 - General
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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.
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29 - General
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Implement network segmentation and segregation [27] 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.
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30 - General
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Utilise secure programming practices for software developed by the CSP [28] [29] [30].
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31 - General
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Perform secure configuration, ongoing vulnerability management, prompt patching, annual third party security reviews and penetration testing of cloud services and underlying infrastructure.
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32 - General
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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.
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Most Effective Risk Mitigations Particularly Relevant to IaaS
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Tenant’s Virtual Machine (VM) compromised by malicious third party [31]
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1 - IaaS
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Provide network access controls enabling the tenant to implement network segmentation and segregation [32], including a network filtering capability to disallow remote administration of their VMs except from their IP address.
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2 - IaaS
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Provide the tenant with securely configured and patched VM template images. Avoid assigning a weak administrative passphrase to newly provisioned VMs.
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Most Effective Risk Mitigations Particularly Relevant to PaaS
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Tenant’s data compromised by malicious third party
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1 - PaaS
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Harden and securely configure operating system, web server and platform software. Limit inbound and outbound network connectivity to only required ports/protocols. Promptly perform patching and log analysis.
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Most Effective Risk Mitigations Particularly Relevant to SaaS
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Tenant’s data compromised by malicious third party
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1 - SaaS
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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.
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2 - SaaS
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Implement general security controls [33] e.g. limited inbound and outbound network connectivity to only required ports/protocols, antivirus software updated daily, intrusion prevention systems and prompt log analysis.
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