Anomalous amount of access denied events for AWS EC2 Instance

cloudtrail

Goal

Detect when an EC2 instance is assessing privileges in AWS through various enumeration and discovery techniques.

Strategy

Monitor CloudTrail logs to identify when an EC2 instance (@userIdentity.session_name:i-*") generates an anomalous amount of AccessDenied events.

Triage and response

  1. Determine what events the EC2 instance {{@userIdentity.session_name}} are generating in the time frame of the signal.
  2. If the root cause is not a misconfiguration, investigate any other signals around the same time of the signal by looking at the Host Investigation dashboard.