AWS STS GetSessionToken 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: 6b08c17de0503620379210c8371dd4a8bb7a04337be4f15d4b808182c121e435

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 GetSessionToken Misuse
id: b45ab1d2-712f-4f01-a751-df3826969807
status: test
description: Identifies the suspicious use of GetSessionToken. Tokens could be created and used by attackers to move laterally and escalate privileges.
references:
    - https://github.com/elastic/detection-rules/pull/1213
    - https://docs.aws.amazon.com/STS/latest/APIReference/API_GetSessionToken.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:
        eventSource: sts.amazonaws.com
        eventName: GetSessionToken
        userIdentity.type: IAMUser
    condition: selection
falsepositives:
    - GetSessionToken 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. GetSessionToken from unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
level: low

Original YAML and metadata in JSON

False positives

• GetSessionToken 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. GetSessionToken from unfamiliar users or hosts should be investigated. If known behavior is causing false positives, it can be exempted from the rule.

Source references

• https://github.com/elastic/detection-rules/pull/1213
• https://docs.aws.amazon.com/STS/latest/APIReference/API_GetSessionToken.html