Compromised AWS EC2 Instance

cloudtrail

Goal

Detect an Impossible Travel event when a @userIdentity.type: {{@userIdentity.type}} uses an AWS EC2 access key and filter out VPNs and AWS Internal IPs.

Strategy

The Impossible Travel detection type’s algorithm compares the GeoIP data of the last log and the current log to determine if the EC2 instance with @userIdentity.session_name: {{@userIdentity.session_name}} traveled more than 500km at over 1,000km/hr and used an AWS EC2 access key.

Triage and response

  1. Determine if the @userIdentity.accessKeyId: {{@userIdentity.accessKeyId}} for @userIdentity.session_name: {{@userIdentity.session_name}} instance should be used from {{@impossible_travel.triggering_locations.first_location.city}}, {{@impossible_travel.triggering_locations.first_location.country}} and {{@impossible_travel.triggering_locations.second_location.city}}, {{@impossible_travel.triggering_locations.second_location.country}}.
  2. If the EC2 access key should not be used from {{@impossible_travel.triggering_locations.first_location.city}}, {{@impossible_travel.triggering_locations.first_location.country}} and {{@impossible_travel.triggering_locations.second_location.city}}, {{@impossible_travel.triggering_locations.second_location.country}}., then consider isolating the account and reset credentials.
  3. Audit any instance actions that may have occurred after the illegitimate login.

NOTE VPNs and other anonymous IPs are filtered out of this signal

Changelog

7 April 2022 - Updated rule name and signal message.