Public NetworkLoadBalancer with service 'NetBios Datagram Service' (TCP:138) is exposed to the entire internet

Risk Level: High
Cloud Entity: Network Load Balancer
CloudGuard Rule ID: D9.AWS.NET.AG2.8.NetworkLoadBalancer.138.TCP
Covered by Spectral: No
Category: Networking & Content Delivery

GSL LOGIC

NetworkLoadBalancer where isPublic=true and nics contain [ subnet.routeTable.associations length()>0 ] and nics contain [ subnet.routeTable.routes contain [ destinationCidrBlock='0.0.0.0/0' and gatewayId regexMatch /gw/ ] ] should not have inboundRules contain [ port<=138  and portTo>=138  and protocol in ('TCP', 'ALL') and scope isPublic() and scope='0.0.0.0/0']

REMEDIATION

Limit the access scope for NetworkLoadBalancer 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: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/authorizing-access-to-an-instance.html

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 https://sc1.checkpoint.com/documents/CloudGuard_Dome9/Documentation/Network-Security/DynAccessLease.html?Highlight=dynamic%20access for more details.

Network Load Balancer

A Network Load Balancer functions at the fourth layer of the Open Systems Interconnection (OSI) model. It can handle millions of requests per second. After the load balancer receives a connection request, it selects a target from the target group for the default rule. It attempts to open a TCP connection to the selected target on the port specified in the listener configuration.

Compliance Frameworks

• BP-0318
• LGPD
• NETWSEC-V2