A security engineer is investigating a malware infection that has spread across a set of...

Enable VPC Flow Logs:

VPC flow logs capture details about the network traffic in your VPC, including both accepted and rejected traffic.

Configure the flow logs to capture traffic for the subnet where the affected EC2 instances are located.

Filter Rejected Traffic:

In the flow log configuration, ensure that you capture rejected traffic (log-status = REJECT).

This will provide a record of instances that attempted to communicate on TCP port 2905 and were blocked by the NACL rule.

Analyze Flow Logs:

Search the flow log records for entries where:

destination-port = 2905

log-status = REJECT

This will help identify the specific EC2 instances attempting to communicate on TCP port 2905.

Advantages of Using VPC Flow Logs:

Cost-effective: No additional infrastructure or services are required.

Scalable: Automatically captures traffic across the subnet without manual intervention.

Detailed Logs: Provides granular details about the rejected traffic.

VPC Flow Logs Documentation

Filtering VPC Flow Logs