Public ELB with service 'NetBios Datagram Service' (UDP:138) is exposed to a small public network

Services and databases store data that may be sensitive, protected by law, subject to regulatory requirements or compliance standards. It is highly recommended that access to data will be restricted to encrypted protocols. This rule detects network settings that may expose data via unencrypted protocol over the public internet or to a too wide local scope.

Risk Level: Medium
Cloud Entity: Elastic Load Balancing (ELB)
CloudGuard Rule ID: D9.AWS.NET.AG2.7.ELB.138.UDP
Covered by Spectral: No
Category: Networking & Content Delivery


ELB where isPublic=true and inboundRules contain [port <= 138 and portTo >= 138 and protocol in ('UDP','ALL')] should not have inboundRules contain [port <= 138 and portTo >= 138 and protocol in ('UDP','ALL') and scope isPublic() and scope numberOfHosts() > 32 and scope numberOfHosts() <=  256]


Limit the access scope for ELB with service 'NetBios Datagram Service to only allow access in internal networks and limited scope.

If public interface exists, remove it and limit the access scope within the VPC only to applications or instances that requires access.

Amazon Reference:

As a further protection step, Use CloudGuard 'Tamper Protection' (Full Protection mode) and region lock to prevent unauthorized changes to network access settings, refer to for more details.

Refer to for more details.

Elastic Load Balancing (ELB)

Elastic Load Balancing automatically distributes incoming application traffic across multiple targets, such as Amazon EC2 instances, containers, and IP addresses. It can handle the varying load of your application traffic in a single Availability Zone or across multiple Availability Zones. Elastic Load Balancing offers three types of load balancers that all feature the high availability, automatic scaling, and robust security necessary to make your applications fault tolerant.

Compliance Frameworks

  • BP-0318
  • LGPD