AWS IAM Backdoor Users Keys — Sigma Rule

Rule metadata and linked tags

Author: faloker. Source status: test; severity: medium. Source dates: 2020-02-12 / 2022-10-09.

{
  "product": "aws",
  "service": "cloudtrail"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 3dd4fe36c892c8fefef93c24f29e5747f2b046ef129c33c92a283d1dcba188d5

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: AWS IAM Backdoor Users Keys
id: 0a5177f4-6ca9-44c2-aacf-d3f3d8b6e4d2
status: test
description: |
  Detects AWS API key creation for a user by another user.
  Backdoored users can be used to obtain persistence in the AWS environment.
  Also with this alert, you can detect a flow of AWS keys in your org.
references:
    - https://github.com/RhinoSecurityLabs/pacu/blob/866376cd711666c775bbfcde0524c817f2c5b181/pacu/modules/iam__backdoor_users_keys/main.py
author: faloker
date: 2020-02-12
modified: 2022-10-09
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1098
logsource:
    product: aws
    service: cloudtrail
detection:
    selection_source:
        eventSource: iam.amazonaws.com
        eventName: CreateAccessKey
    filter:
        userIdentity.arn|contains: responseElements.accessKey.userName
    condition: selection_source and not filter
falsepositives:
    - Adding user keys to their own accounts (the filter cannot cover all possible variants of user naming)
    - AWS API keys legitimate exchange workflows
level: medium

Original YAML and metadata in JSON

False positives

• Adding user keys to their own accounts (the filter cannot cover all possible variants of user naming)
• AWS API keys legitimate exchange workflows

Source references

• https://github.com/RhinoSecurityLabs/pacu/blob/866376cd711666c775bbfcde0524c817f2c5b181/pacu/modules/iam__backdoor_users_keys/main.py