AWS STS AssumeRole Misuse — Sigma Rule

Rule metadata and linked tags

Author: Austin Songer @austinsonger. Source status: test; severity: low. Source dates: 2021-07-24 / 2022-10-09.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 6d5a489785cb83e1d7459733493874d0b18ecee6e76a155f932b0723504a5d78

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 STS AssumeRole Misuse
id: 905d389b-b853-46d0-9d3d-dea0d3a3cd49
status: test
description: Identifies the suspicious use of AssumeRole. Attackers could move laterally and escalate privileges.
references:
    - https://github.com/elastic/detection-rules/pull/1214
    - https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html
author: Austin Songer @austinsonger
date: 2021-07-24
modified: 2022-10-09
tags:
    - attack.lateral-movement
    - attack.privilege-escalation
    - attack.t1548
    - attack.t1550
    - attack.t1550.001
logsource:
    product: aws
    service: cloudtrail
detection:
    selection:
        userIdentity.type: AssumedRole
        userIdentity.sessionContext.sessionIssuer.type: Role
    condition: selection
falsepositives:
    - AssumeRole may be done by a system or network administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
    - AssumeRole from unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
    - Automated processes that uses Terraform may lead to false positives.
level: low

Original YAML and metadata in JSON

False positives

• AssumeRole may be done by a system or network administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
• AssumeRole from unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
• Automated processes that uses Terraform may lead to false positives.

Source references

• https://github.com/elastic/detection-rules/pull/1214
• https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html