Information
A _route table_ contains a set of rules, called _routes_, that are used to determine where network traffic is directed.
Each subnet in your VPC must be associated with a route table; the table controls the routing for the subnet. A subnet can only be associated with one route table at a time, but you can associate multiple subnets with the same route table.
The default route (0.0.0.0/0) should be pointing to the NAT Gateway in order to provide internet connectivity for the Web tier instances.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
Using the Amazon unified command line interface:
* For the above route tables, if the default route (0.0.0.0/0) exists but it doesn't have a NAT GW configured as gateway:
aws ec2 replace-route --route-table-id _<route_table_id>_ --destination-cidr-block 0.0.0.0/0 --gateway-id _<vpc_nat_gw>_
* For the above route tables, if the default route (0.0.0.0/0) doesn't exist:
aws ec2 create-route --route-table-id _<route_table_id>_ --destination-cidr-block 0.0.0.0/0 --gateway-id _<vpc_nat_gw>_