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

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

Stats​

not available

Logic​

Similar Policies​

  • Internal: dec-x-749f6d5f

Similar Internal Rules​

RulePoliciesFlags
βœ‰οΈ dec-x-749f6d5f3

Description​

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Description​

Ensure that Azure VM Scale Set Instances are not configured to allow unrestricted inbound access to the CIFS (Common Internet File System) service on TCP port 445. CIFS is a network file-sharing protocol used primarily by Windows-based systems for accessing and sharing files over a network. While essential in certain scenarios, exposing TCP port 445 to the public internet poses a significant security risk. Access to CIFS should be strictly limited to trusted IP addresses and networks to mitigate the risk of unauthorized access and data compromise.

Rationale​

Unrestricted access to CIFS over TCP port 445 significantly increases the attack surface of your environment. Threat actors commonly target this port to exploit vulnerabilities in file-sharing protocols, potentially resulting in unauthorized access, data leakage, or lateral movement within the network. Restricting CIFS access to only trusted networks and enforcing appropriate network security controls aligns with the principle of least privilege and is a critical step toward safeguarding sensitive resources.

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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 36d access management controls β€”only authorised users, software and hardware are able to access information assets (refer to Attachment B for further guidance);4161no data
πŸ’Ό APRA CPG 234 β†’ πŸ’Ό 36e hardware and software asset controls β€”appropriate authorisation to prevent security compromises from unauthorised hardware and software assets;4464no data
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 Cloudaware Framework β†’ πŸ’Ό Network Exposure137no 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 Moderate Security Controls β†’ πŸ’Ό AC-4(21) Physical or Logical Separation of Information Flows (M)(H)141no data
πŸ’Ό ISO/IEC 27001:2013 β†’ πŸ’Ό A.9.4.1 Information access restriction4992no 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.DS-5: Protections against data leaks are implemented89152no 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.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 SP 800-53 Revision 5 β†’ πŸ’Ό AC-4(21) Information Flow Enforcement _ Physical or Logical Separation of Information Flows83141no 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 2.2.4 Configure system security parameters to prevent misuse.40no 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 2.2.6 System security parameters are configured to prevent misuse.40no 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 2.2.6 System security parameters are configured to prevent misuse.2340no data
πŸ’Ό UK Cyber Essentials β†’ πŸ’Ό 1.2 Prevent access to the administrative interface from the internet85119no data