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🛡️ AWS VPC Subnet Map Public IP On Launch is enabled🟢

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Description​

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Description​

This policy identifies AWS VPC Subnets that are configured to automatically assign public IPv4 addresses and/or IPv6 addresses to instances launched within them.

Rationale​

Public IP address assignment should be an intentional and controlled action. When subnet-level auto-assignment settings are enabled, all instances launched into the subnet (unless explicitly overridden) automatically receive externally routable IP addresses.

  • Map Public IP On Launch assigns a public IPv4 address.
  • Assign IPv6 Address On Creation assigns an IPv6 address from the subnet's IPv6 CIDR block.

Enabling either setting can unintentionally expose resources to external networks, increasing the attack surface and the risk of unauthorized access. These settings should be enabled only for subnets explicitly designed for internet-facing workloads.

Audit​

This policy flags an AWS VPC Subnet as INCOMPLIANT if either of the following conditions is met:

  • Map Public IP On Launch is set to true
  • Assign IPv6 Address On Creation is set to true

Remediation​

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Remediation​

Disable automatic public IP assignment at the subnet level​

Disable both IPv4 and IPv6 auto-assignment settings on the subnet to ensure that IP address exposure is explicitly controlled.

From Command Line​

Disable auto-assign public IPv4 addresses​
aws ec2 modify-subnet-attribute \
    --subnet-id {{subnet-id}} \
    --no-map-public-ip-on-launch
Disable auto-assign IPv6 addresses on instance creation​
aws ec2 modify-subnet-attribute \
    --subnet-id {{subnet-id}} \
    --no-assign-ipv6-address-on-creation

Considerations​

  • These changes apply only to instances launched after the modification.
  • Existing instances retain their currently assigned IPv4 and IPv6 addresses.

policy.yaml​

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Linked Framework Sections​

SectionSub SectionsInternal RulesPoliciesFlagsCompliance
💼 AWS Foundational Security Best Practices v1.0.0 → 💼 [EC2.15] Amazon EC2 subnets should not automatically assign public IP addresses1no data
💼 Cloudaware Framework → 💼 Network Exposure137no data
💼 FedRAMP High Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)49103no data
💼 FedRAMP High Security Controls → 💼 AC-4 Information Flow Enforcement (M)(H)248188no data
💼 FedRAMP High Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)18141no data
💼 FedRAMP High Security Controls → 💼 AC-6 Least Privilege (M)(H)81287no data
💼 FedRAMP High Security Controls → 💼 AC-21 Information Sharing (M)(H)19no data
💼 FedRAMP High Security Controls → 💼 SC-7 Boundary Protection (L)(M)(H)10999no data
💼 FedRAMP High Security Controls → 💼 SC-7(3) Access Points (M)(H)19no data
💼 FedRAMP High Security Controls → 💼 SC-7(4) External Telecommunications Services (M)(H)49no data
💼 FedRAMP High Security Controls → 💼 SC-7(20) Dynamic Isolation and Segregation (H)20no data
💼 FedRAMP High Security Controls → 💼 SC-7(21) Isolation of System Components (H)37no data
💼 FedRAMP Low Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)103no data
💼 FedRAMP Low Security Controls → 💼 SC-7 Boundary Protection (L)(M)(H)50no data
💼 FedRAMP Moderate Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)103no data
💼 FedRAMP Moderate Security Controls → 💼 AC-4 Information Flow Enforcement (M)(H)1169no data
💼 FedRAMP Moderate Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)141no data
💼 FedRAMP Moderate Security Controls → 💼 AC-6 Least Privilege (M)(H)687no data
💼 FedRAMP Moderate Security Controls → 💼 AC-21 Information Sharing (M)(H)19no data
💼 FedRAMP Moderate Security Controls → 💼 SC-7 Boundary Protection (L)(M)(H)783no data
💼 FedRAMP Moderate Security Controls → 💼 SC-7(3) Access Points (M)(H)19no data
💼 FedRAMP Moderate Security Controls → 💼 SC-7(4) External Telecommunications Services (M)(H)49no data
💼 NIST CSF v2.0 → 💼 DE.CM-01: Networks and network services are monitored to find potentially adverse events187no data
💼 NIST CSF v2.0 → 💼 DE.CM-09: Computing hardware and software, runtime environments, and their data are monitored to find potentially adverse events185no data
💼 NIST CSF v2.0 → 💼 ID.AM-03: Representations of the organization's authorized network communication and internal and external network data flows are maintained128no data
💼 NIST CSF v2.0 → 💼 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
💼 NIST CSF v2.0 → 💼 PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected248no data
💼 NIST CSF v2.0 → 💼 PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected219no data
💼 NIST CSF v2.0 → 💼 PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected249no data
💼 NIST CSF v2.0 → 💼 PR.IR-01: Networks and environments are protected from unauthorized logical access and usage165no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-3 Access Enforcement15866no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-3(7) Access Enforcement _ Role-based Access Control36no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-4 Information Flow Enforcement32120207no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-4(21) Information Flow Enforcement _ Physical or Logical Separation of Information Flows83141no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-6 Least Privilege102580no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-21 Information Sharing219no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7 Boundary Protection2911108no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(3) Boundary Protection _ Access Points19no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(4) Boundary Protection _ External Telecommunications Services49no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(9) Boundary Protection _ Restrict Threatening Outgoing Communications Traffic35no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(11) Boundary Protection _ Restrict Incoming Communications Traffic37no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(16) Boundary Protection _ Prevent Discovery of System Components37no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(20) Boundary Protection _ Dynamic Isolation and Segregation20no data
💼 NIST SP 800-53 Revision 5 → 💼 SC-7(21) Boundary Protection _ Isolation of System Components37no data
💼 PCI DSS v3.2.1 → 💼 1.3.6 Place system components that store cardholder data in an internal network zone, segregated from the DMZ and other untrusted networks.15no data
💼 PCI DSS v4.0.1 → 💼 1.4.4 System components that store cardholder data are not directly accessible from untrusted networks.15no data
💼 PCI DSS v4.0 → 💼 1.4.4 System components that store cardholder data are not directly accessible from untrusted networks.15no data