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🛡️ AWS EC2 Security Group allows unrestricted DNS traffic🟢

  • Contextual name: 🛡️ Security Group allows unrestricted DNS traffic🟢
  • ID: /ce/ca/aws/ec2/security-group-allows-unrestricted-dns-traffic
  • Tags:
  • Policy Type: COMPLIANCE_POLICY
  • Policy Categories: SECURITY

Logic​

Similar Policies​

Similar Internal Rules​

RulePoliciesFlags
✉️ dec-z-dbeeed9f1
✉️ dec-z-f778950c1

Description​

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Description​

AWS EC2 Security Groups should not allow unrestricted DNS traffic to avoid exposure to security vulnerabilities. Security group rules should be configured to limit DNS traffic (UDP port 53) to trusted IP ranges, such as internal networks or approved DNS servers, reducing the risk of misuse or attacks such as DNS amplification.

Rationale​

Restricting DNS traffic prevents unauthorized use of EC2 instances for malicious activities, such as DNS tunneling or participating in amplification attacks. By limiting DNS access to trusted sources, you ensure only authorized clients and servers can interact, reducing the surface area for potential exploits.

Impact​

Implementing restrictions might cause service interruptions if legitimate applications are not properly configured to use allowed DNS servers, making it essential to validate and update configurations thoroughly during remediation.

Audit​

This policy marks an EC2 Security Group as INCOMPLIANT if it contains a rule that meets all the following conditions:

... see more

Remediation​

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Remediation​

From Command Line​

  1. Run the following command to remove or modify the unrestricted rule for DNS access:
aws ec2 revoke-security-group-ingress \
--region {{region-name}} \
--group-id {{security-group-id}} \
--protocol {{protocol}} \
--port 53 \
--cidr {{0.0.0.0/0 or ::/0}}

  • Optionally, run the authorise-security-group-ingress command to create a new rule, specifying a trusted CIDR range instead of 0.0.0.0/0.

  1. Confirm the changes by describing the security group again and ensuring the unrestricted access rule has been removed or appropriately restricted:
aws ec2 describe-security-groups \
--region {{region-name}} \
--group-ids {{security-group-id}} \
--query 'SecurityGroups[*].IpPermissions[?FromPort==`53`].{CIDR:IpRanges[*].CidrIp,Port:FromPort}'
  1. Test the functionality of services that rely on DNS to ensure that they operate correctly with the updated security group rules.

policy.yaml​

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Linked Framework Sections​

SectionSub SectionsInternal RulesPoliciesFlagsCompliance
💼 APRA CPG 234 → 💼 36f network design — to ensure authorised network traffic flows and to reduce the impact of security compromises;2930no data
💼 APRA CPG 234 → 💼 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.3537no data
💼 Cloudaware Framework → 💼 Threat Protection29no data
💼 FedRAMP High Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)3767no data
💼 FedRAMP High Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)1146no data
💼 FedRAMP High Security Controls → 💼 CM-7(1) Periodic Review (M)(H)1212no data
💼 FedRAMP Low Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)67no data
💼 FedRAMP Moderate Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)67no data
💼 FedRAMP Moderate Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)46no data
💼 FedRAMP Moderate Security Controls → 💼 CM-7(1) Periodic Review (M)(H)12no data
💼 ISO/IEC 27001:2013 → 💼 A.9.1.2 Access to networks and network services1718no data
💼 NIST CSF v1.1 → 💼 PR.AC-4: Access permissions and authorizations are managed, incorporating the principles of least privilege and separation of duties1752no data
💼 NIST CSF v1.1 → 💼 PR.DS-5: Protections against data leaks are implemented4766no data
💼 NIST CSF v1.1 → 💼 PR.PT-3: The principle of least functionality is incorporated by configuring systems to provide only essential capabilities2130no 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 duties91no data
💼 NIST CSF v2.0 → 💼 PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected118no data
💼 NIST CSF v2.0 → 💼 PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected98no data
💼 NIST CSF v2.0 → 💼 PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected112no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-4(21) Information Flow Enforcement _ Physical or Logical Separation of Information Flows3746no data
💼 PCI DSS v3.2.1 → 💼 1.1 Establish and implement firewall and router configuration standards7139no data
💼 PCI DSS v3.2.1 → 💼 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.127no data
💼 PCI DSS v3.2.1 → 💼 1.2.1 Restrict inbound and outbound traffic to that which is necessary for the cardholder data environment, and specifically deny all other traffic.1035no data
💼 PCI DSS v4.0.1 → 💼 1.2.1 Configuration standards for NSC rulesets are defined, implemented, maintained.34no data
💼 PCI DSS v4.0.1 → 💼 1.2.5 All services, protocols, and ports allowed are identified, approved, and have a defined business need.27no data
💼 PCI DSS v4.0.1 → 💼 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.27no data
💼 PCI DSS v4.0.1 → 💼 1.3.1 Inbound traffic to the CDE is restricted.35no data
💼 PCI DSS v4.0.1 → 💼 1.3.2 Outbound traffic from the CDE is restricted.35no data
💼 PCI DSS v4.0 → 💼 1.2.1 Configuration standards for NSC rulesets are defined, implemented, maintained.2434no data
💼 PCI DSS v4.0 → 💼 1.2.5 All services, protocols, and ports allowed are identified, approved, and have a defined business need.1527no data
💼 PCI DSS v4.0 → 💼 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.627no data
💼 PCI DSS v4.0 → 💼 1.3.1 Inbound traffic to the CDE is restricted.735no data
💼 PCI DSS v4.0 → 💼 1.3.2 Outbound traffic from the CDE is restricted.35no data
💼 SOC 2 → 💼 CC6.1-7 Restricts Access to Information Assets1326no data
💼 SOC 2 → 💼 CC6.6-1 Restricts Access1619no data
💼 UK Cyber Essentials → 💼 1.2 Prevent access to the administrative interface from the internet3638no data