📝 AWS EC2 Security Group allows unrestricted NetBIOS traffic 🟢

• Contextual name: 📝 Security Group allows unrestricted NetBIOS traffic 🟢
• ID: /ce/ca/aws/ec2/security-group-allows-unrestricted-netbios-traffic
• Located in: 📁 AWS EC2

Flags

• 🟢 Policy with categories
• 🟢 Policy with type
• 🟢 Production policy

Our Metadata

• Policy Type: COMPLIANCE_POLICY
• Policy Category:
  • SECURITY

Similar Policies

• Cloud Conformity
  • Unrestricted NetBIOS Access
• Internal
  • dec-x-6eab9b88

Similar Internal Rules

Rule	Policies	Flags
✉️ dec-x-6eab9b88	1

Logic

• 🧠 prod.logic.yaml 🟢
  • 📗 AWS EC2 Security Group
  • 🔌 AWS EC2 Security Group Rule - object.extracts.yaml
  • 🧪 test-data.json

Description

Open File

Description

It is recommended to evaluate and restrict the configuration of AWS EC2 security groups to prevent unrestricted NetBIOS traffic (TCP: 137, 139, UDP: 137, 138). NetBIOS is often used in legacy systems for file sharing and network management in Windows environments, but exposing these ports publicly can pose significant security risks.

Rational

Restricting NetBIOS traffic in security groups reduces the attack surface of your EC2 instances, enhancing the overall security posture. NetBIOS is known to be vulnerable to exploitation and is rarely required in modern cloud-based applications. Addressing this configuration minimizes the risk of unauthorized access, data exfiltration, and the spread of malicious payloads.

Impact

Restrictions could also disrupt legitimate operations for systems relying on NetBIOS for communication. Therefore, should be carefully implemented, ensuring that it does not interfere with necessary business functions.

Audit

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

... see more

Remediation

Open File

Remediation

From Command Line

1. Run the following command to remove or modify the unrestricted rule for NetBIOS access:

aws ec2 revoke-security-group-ingress \
--region {{region-name}} \
--group-id {{security-group-id}} \
--protocol {{protocol}} \
--port {{137, 138, or 139}} \
--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.

2. 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==`137`].{CIDR:IpRanges[*].CidrIp,Port:FromPort}'

3. Confirm that application functionality is unaffected by the updated rules.

policy.yaml

Open File

Linked Framework Sections

Section	Sub Sections	Internal Rules	Policies	Flags
💼 APRA CPG 234 → 💼 36f network design — to ensure authorised network traffic flows and to reduce the impact of security compromises;		29	30
💼 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.		35	37
💼 Cloudaware Framework → 💼 Threat Protection			27
💼 FedRAMP High Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)		37	64
💼 FedRAMP High Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)		11	42
💼 FedRAMP High Security Controls → 💼 CM-7(1) Periodic Review (M)(H)		12	12
💼 FedRAMP Low Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)			64
💼 FedRAMP Moderate Security Controls → 💼 AC-3 Access Enforcement (L)(M)(H)			64
💼 FedRAMP Moderate Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)			42
💼 FedRAMP Moderate Security Controls → 💼 CM-7(1) Periodic Review (M)(H)			12
💼 ISO/IEC 27001:2013 → 💼 A.9.1.2 Access to networks and network services		17	18
💼 NIST CSF v1.1 → 💼 PR.AC-4: Access permissions and authorizations are managed, incorporating the principles of least privilege and separation of duties		17	52
💼 NIST CSF v1.1 → 💼 PR.DS-5: Protections against data leaks are implemented		47	66
💼 NIST CSF v1.1 → 💼 PR.PT-3: The principle of least functionality is incorporated by configuring systems to provide only essential capabilities		21	30
💼 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 duties			88
💼 NIST CSF v2.0 → 💼 PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected			114
💼 NIST CSF v2.0 → 💼 PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected			94
💼 NIST CSF v2.0 → 💼 PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected			108
💼 NIST SP 800-53 Revision 5 → 💼 AC-4(21) Information Flow Enforcement _ Physical or Logical Separation of Information Flows		37	42
💼 PCI DSS v3.2.1 → 💼 1.1 Establish and implement firewall and router configuration standards	7	1	38
💼 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.		1	27
💼 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.		10	35
💼 PCI DSS v3.2.1 → 💼 2.2.3 Implement additional security features for any required services, protocols, or daemons that are considered to be insecure.		3	3
💼 PCI DSS v3.2.1 → 💼 2.2.4 Configure system security parameters to prevent misuse.			16
💼 PCI DSS v4.0.1 → 💼 1.2.1 Configuration standards for NSC rulesets are defined, implemented, maintained.			34
💼 PCI DSS v4.0.1 → 💼 1.2.5 All services, protocols, and ports allowed are identified, approved, and have a defined business need.			27
💼 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.			27
💼 PCI DSS v4.0.1 → 💼 1.3.1 Inbound traffic to the CDE is restricted.			35
💼 PCI DSS v4.0.1 → 💼 1.3.2 Outbound traffic from the CDE is restricted.			35
💼 PCI DSS v4.0.1 → 💼 2.2.5 If any insecure services, protocols, or daemons are present, business justification is documented.			3
💼 PCI DSS v4.0.1 → 💼 2.2.6 System security parameters are configured to prevent misuse.			16
💼 PCI DSS v4.0 → 💼 1.2.1 Configuration standards for NSC rulesets are defined, implemented, maintained.		24	34
💼 PCI DSS v4.0 → 💼 1.2.5 All services, protocols, and ports allowed are identified, approved, and have a defined business need.		15	27
💼 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.		6	27
💼 PCI DSS v4.0 → 💼 1.3.1 Inbound traffic to the CDE is restricted.		7	35
💼 PCI DSS v4.0 → 💼 1.3.2 Outbound traffic from the CDE is restricted.			35
💼 PCI DSS v4.0 → 💼 2.2.5 If any insecure services, protocols, or daemons are present, business justification is documented.			3
💼 PCI DSS v4.0 → 💼 2.2.6 System security parameters are configured to prevent misuse.		12	16
💼 SOC 2 → 💼 CC6.1-7 Restricts Access to Information Assets		13	26
💼 SOC 2 → 💼 CC6.6-1 Restricts Access		16	19
💼 UK Cyber Essentials → 💼 1.2 Prevent access to the administrative interface from the internet		36	38