Compromised AWS IAM User Access Key

cloudtrail
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Goal

Detect an Impossible Travel event when a @userIdentity.type: {{@userIdentity.type}} uses an AWS IAM 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 IAM user with @userIdentity.session_name: {{@userIdentity.session_name}} traveled more than 500km at over 1,000km/hr and used an AWS IAM access key.

Triage and response

  1. Determine if the @userIdentity.accessKeyId: {{@userIdentity.accessKeyId}} for @userIdentity.session_name: {{@userIdentity.session_name}} 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 IAM user 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 user actions that may have occurred after the illegitimate login.

Changelog

  • 7 April 2022 - Updated signal message.
  • 3 August 2022 - Fixed null groupby field in query.
  • 11 September 2024 - Tuned rule to remove internal network IPs and the three major cloud provider IPs: Azure, AWS, and GCP.
  • 30 September 2024 - Updated query to replace attribute @threat_intel.results.subcategory:anonymizer.
  • 18 November 2024 - Updated query to remove when accessKeyId is empty.