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πŸ›‘οΈ Azure VM Scale Set Instance allows public access to SSH port🟒

  • Contextual name: πŸ›‘οΈ Instance allows public access to SSH port🟒
  • ID: /ce/ca/azure/vm-scale-set/instance-allows-unrestricted-ssh-traffic
  • Tags:
  • Policy Type: COMPLIANCE_POLICY
  • Policy Categories: SECURITY

Stats​

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Logic​

Similar Policies​

  • Internal: dec-x-599c86b4

Similar Internal Rules​

RulePoliciesFlags
βœ‰οΈ dec-x-599c86b43

Description​

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Description​

Ensure that Azure VM Scale Set Instances are not configured to allow unrestricted inbound access to the Secure Shell (SSH) port (TCP 22). SSH is widely used for remote management of Linux-based systems. Leaving SSH ports open to the public internet increases the risk of brute-force attacks, credential theft, and unauthorized system access.

Rationale​

Restricting SSH access through NSGs is a critical step in reducing the attack surface of Azure VM Scale Set Instances. Public exposure of SSH enables malicious actors to attempt automated attacks, exploit misconfigurations, or leverage stolen credentials. Access to SSH should be limited to trusted IP ranges or secured through bastion hosts or private connectivity methods.

Impact​

Blocking public access to SSH may disrupt workflows that involve direct internet-based remote management. It is important to transition to secure access alternatives, such as VPN tunnels or Azure Bastion, to maintain administrative capabilities without exposing sensitive management ports to external threats.

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Remediation​

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Remediation​

Modify or Remove Insecure NSG Rule​

Review the security rules associated with the relevant Network Security Group (NSG) and determine whether they are required. Take appropriate action based on necessity and scope:

  • If the rule is not required: Remove the rule entirely.

  • If the rule is required but overly permissive: Update the rule to narrowly scope access, restricting the source IP range to only what is strictly necessary.

Azure CLI​

  1. Delete the rule:

    az network nsg rule delete \
      --resource-group {{resource-group-name}} \
      --nsg-name {{nsg-name}} \
      --name {{rule-name}}

  2. Restrict the rule:

    az network nsg rule update \
        --resource-group {{resource-group-name}} \
        --nsg-name {{nsg-name}} \
        --name {{rule-name}} \
        --source-address-prefixes {{trusted-cidr}}

    Replace placeholders with the appropriate values. Use space-separated values for multiple source prefixes or destination ports (e.g., --source-address-prefixes "1.2.3.4/32 5.6.7.8/32").

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policy.yaml​

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Linked Framework Sections​

SectionSub SectionsInternal RulesPoliciesFlagsCompliance
πŸ’Ό APRA CPG 234 β†’ πŸ’Ό 36f network design β€” to ensure authorised network traffic flows and to reduce the impact of security compromises;76107no data
πŸ’Ό APRA CPG 234 β†’ πŸ’Ό 45 An understanding of plausible worst case scenarios can help regulated entities identify and implement additional controls to prevent or reduce the impact of such scenarios. One example is malware that infects computers and encrypts data, both on the infected computer and any connected storage, including (corporate) networks and cloud storage. Such attacks reinforce the importance of protecting the backup environment in the event that the production environment is compromised. Common techniques to achieve this include network segmentation, highly restricted and segregated access controls and network traffic flow restrictions.83115no data
πŸ’Ό CIS Azure v1.1.0 β†’ πŸ’Ό 6.2 Ensure that SSH access is restricted from the internetπŸ”΄13πŸ”΄ x1no data
πŸ’Ό CIS Azure v1.3.0 β†’ πŸ’Ό 6.2 Ensure that SSH access is restricted from the internet - Level 1 (Automated)πŸ”΄13πŸ”΄ x1no data
πŸ’Ό CIS Azure v1.4.0 β†’ πŸ’Ό 6.2 Ensure that SSH access is restricted from the internet - Level 1 (Automated)πŸ”΄13πŸ”΄ x1no data
πŸ’Ό CIS Azure v1.5.0 β†’ πŸ’Ό 6.2 Ensure that SSH access from the Internet is evaluated and restricted - Level 1 (Automated)πŸ”΄13πŸ”΄ x1no data
πŸ’Ό CIS Azure v2.0.0 β†’ πŸ’Ό 6.2 Ensure that SSH access from the Internet is evaluated and restricted - Level 1 (Automated)πŸ”΄13πŸ”΄ x1no data
πŸ’Ό CIS Azure v2.1.0 β†’ πŸ’Ό 6.2 Ensure that SSH access from the Internet is evaluated and restricted - Level 1 (Automated)πŸ”΄13πŸ”΄ x1no data
πŸ’Ό CIS Azure v3.0.0 β†’ πŸ’Ό 7.2 Ensure that SSH access from the Internet is evaluated and restricted (Automated)πŸ”΄3πŸ”΄ x1no data
πŸ’Ό CIS Azure v4.0.0 β†’ πŸ’Ό 8.2 Ensure that SSH access from the Internet is evaluated and restricted (Automated)πŸ”΄3πŸ”΄ x1no data
πŸ’Ό CIS Azure v5.0.0 β†’ πŸ’Ό 7.2 Ensure that SSH access from the Internet is evaluated and restricted (Automated)πŸ”΄3πŸ”΄ x1no data
πŸ’Ό CIS Azure v6.0.0 β†’ πŸ’Ό 7.2 Ensure that SSH Access from the Internet is Evaluated and Restricted (Automated)πŸ”΄3πŸ”΄ x1no data
πŸ’Ό Cloudaware Framework β†’ πŸ’Ό Network Exposure137no data
πŸ’Ό FedRAMP High Security Controls β†’ πŸ’Ό AC-3 Access Enforcement (L)(M)(H)49103no data
πŸ’Ό FedRAMP High Security Controls β†’ πŸ’Ό AC-4(21) Physical or Logical Separation of Information Flows (M)(H)18141no data
πŸ’Ό FedRAMP High Security Controls β†’ πŸ’Ό CM-7 Least Functionality (L)(M)(H)32545no data
πŸ’Ό FedRAMP High Security Controls β†’ πŸ’Ό SC-7(5) Deny by Default β€” Allow by Exception (M)(H)34no data
πŸ’Ό FedRAMP Low Security Controls β†’ πŸ’Ό AC-3 Access Enforcement (L)(M)(H)103no data
πŸ’Ό FedRAMP Low Security Controls β†’ πŸ’Ό CM-7 Least Functionality (L)(M)(H)36no data
πŸ’Ό FedRAMP Moderate Security Controls β†’ πŸ’Ό AC-3 Access Enforcement (L)(M)(H)103no data
πŸ’Ό FedRAMP Moderate Security Controls β†’ πŸ’Ό AC-4(21) Physical or Logical Separation of Information Flows (M)(H)141no data
πŸ’Ό FedRAMP Moderate Security Controls β†’ πŸ’Ό CM-7 Least Functionality (L)(M)(H)345no data
πŸ’Ό FedRAMP Moderate Security Controls β†’ πŸ’Ό SC-7(5) Deny by Default β€” Allow by Exception (M)(H)34no data
πŸ’Ό HIPAA Security Rules β†’ πŸ’Ό 164.312(e)(1) Transmission Security (R)210no data
πŸ’Ό ISO/IEC 27001:2013 β†’ πŸ’Ό A.9.1.2 Access to networks and network services2767no data
πŸ’Ό ISO/IEC 27001:2013 β†’ πŸ’Ό A.9.4.1 Information access restriction4992no data
πŸ’Ό ISO/IEC 27001:2013 β†’ πŸ’Ό A.13.1.1 Network controls65no data
πŸ’Ό ISO/IEC 27001:2022 β†’ πŸ’Ό 5.14 Information transfer916no data
πŸ’Ό ISO/IEC 27001:2022 β†’ πŸ’Ό 6.7 Remote working518no data
πŸ’Ό ISO/IEC 27001:2022 β†’ πŸ’Ό 8.1 User end point devices1431no data
πŸ’Ό ISO/IEC 27001:2022 β†’ πŸ’Ό 8.16 Monitoring activities519no data
πŸ’Ό ISO/IEC 27001:2022 β†’ πŸ’Ό 8.22 Segregation of networks518no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό DE.AE-1: A baseline of network operations and expected data flows for users and systems is established and managed1179no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.AC-3: Remote access is managed66no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.AC-4: Access permissions and authorizations are managed, incorporating the principles of least privilege and separation of duties48127no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.AC-5: Network integrity is protected (e.g., network segregation, network segmentation)1184no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.DS-2: Data-in-transit is protected1797no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.DS-5: Protections against data leaks are implemented89152no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.IP-1: A baseline configuration of information technology/industrial control systems is created and maintained incorporating security principles (e.g. concept of least functionality)533no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.PT-3: The principle of least functionality is incorporated by configuring systems to provide only essential capabilities3179no data
πŸ’Ό NIST CSF v1.1 β†’ πŸ’Ό PR.PT-4: Communications and control networks are protected1184no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό ID.AM-03: Representations of the organization's authorized network communication and internal and external network data flows are maintained128no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.AA-03: Users, services, and hardware are authenticated102no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.AA-05: Access permissions, entitlements, and authorizations are defined in a policy, managed, enforced, and reviewed, and incorporate the principles of least privilege and separation of duties199no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.AA-06: Physical access to assets is managed, monitored, and enforced commensurate with risk84no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected248no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected219no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected249no data
πŸ’Ό NIST CSF v2.0 β†’ πŸ’Ό PR.IR-01: Networks and environments are protected from unauthorized logical access and usage165no data
πŸ’Ό NIST SP 800-53 Revision 5 β†’ πŸ’Ό AC-4(21) Information Flow Enforcement _ Physical or Logical Separation of Information Flows83141no data
πŸ’Ό NIST SP 800-53 Revision 5 β†’ πŸ’Ό SC-7(5) Boundary Protection _ Deny by Default β€” Allow by Exception1134no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.1 Establish and implement firewall and router configuration standards71110no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.1.6 Documentation of business justification and approval for use of all services, protocols, and ports allowed, including documentation of security features implemented for those protocols considered to be insecure.195no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.2.1 Restrict inbound and outbound traffic to that which is necessary for the cardholder data environment, and specifically deny all other traffic.16111no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.3 Prohibit direct public access between the Internet and any system component in the cardholder data environment.712113no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.3.1 Implement a DMZ to limit inbound traffic to only system components that provide authorized publicly accessible services, protocols, and ports.10100no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.3.2 Limit inbound Internet traffic to IP addresses within the DMZ.100no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 1.3.5 Permit only β€œestablished” connections into the network.100no data
πŸ’Ό PCI DSS v3.2.1 β†’ πŸ’Ό 2.3 Encrypt all non-console administrative access using strong cryptography.527no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.2.1 Configuration standards for NSC rulesets are defined, implemented, maintained.105no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.2.5 All services, protocols, and ports allowed are identified, approved, and have a defined business need.95no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.2.6 Security features are defined and implemented for all services, protocols, and ports that are in use and considered to be insecure, such that the risk is mitigated.95no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.3.1 Inbound traffic to the CDE is restricted.111no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.3.2 Outbound traffic from the CDE is restricted.111no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.4.1 NSCs are implemented between trusted and untrusted networks.90no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 1.4.2 Inbound traffic from untrusted networks to trusted networks is restricted.100no data
πŸ’Ό PCI DSS v4.0.1 β†’ πŸ’Ό 2.2.7 All non-console administrative access is encrypted using strong cryptography.27no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.2.1 Configuration standards for NSC rulesets are defined, implemented, maintained.62105no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.2.5 All services, protocols, and ports allowed are identified, approved, and have a defined business need.4795no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.2.6 Security features are defined and implemented for all services, protocols, and ports that are in use and considered to be insecure, such that the risk is mitigated.2195no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.3.1 Inbound traffic to the CDE is restricted.31111no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.3.2 Outbound traffic from the CDE is restricted.111no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.4.1 NSCs are implemented between trusted and untrusted networks.3190no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 1.4.2 Inbound traffic from untrusted networks to trusted networks is restricted.31100no data
πŸ’Ό PCI DSS v4.0 β†’ πŸ’Ό 2.2.7 All non-console administrative access is encrypted using strong cryptography.1127no data
πŸ’Ό SOC 2 β†’ πŸ’Ό CC6.1-3 Restricts Logical Access430no data
πŸ’Ό SOC 2 β†’ πŸ’Ό CC6.1-7 Restricts Access to Information Assets1867no data
πŸ’Ό SOC 2 β†’ πŸ’Ό CC6.1-8 Manages Identification and Authentication2234no data
πŸ’Ό SOC 2 β†’ πŸ’Ό CC6.6-1 Restricts Access2162no data
πŸ’Ό SOC 2 β†’ πŸ’Ό CC6.6-4 Implements Boundary Protection Systems9no data
πŸ’Ό UK Cyber Essentials β†’ πŸ’Ό 1.2 Prevent access to the administrative interface from the internet85119no data