Risk Level: High
Cloud Entity: Network Load Balancer
CloudGuard Rule ID: D9.AWS.NET.AG2.3.NetworkLoadBalancer.53.UDP
Covered by Spectral: No
Category: Networking & Content Delivery
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<=53 and portTo>=53 and protocol in ('UDP', 'ALL') and scope isPublic() and scope numberOfHosts()>=32 ]
Limit the access scope for NetworkLoadBalancer with service 'DNS 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.
As a further protection, use CloudGuard Dynamic Access Leasing to limit access to SSH/Remote Desktop only from allowed sources and only when needed.
For more information please refer to: https://sc1.checkpoint.com/documents/CloudGuard_Dome9/Documentation/Network-Security/DynAccessLease.html?tocpath=Network%20Security%7C_____3
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.
Updated 4 days ago