AWS Suspicious SAML Activity — Sigma Rule

Rule metadata and linked tags

Author: Austin Songer. Source status: test; severity: medium. Source dates: 2021-09-22 / 2022-12-18.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: c90617886006d86216ea86cce6fc275be6504f61e1142770a2ee9c5ffa5bad8e

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 Suspicious SAML Activity
id: f43f5d2f-3f2a-4cc8-b1af-81fde7dbaf0e
status: test
description: Identifies when suspicious SAML activity has occurred in AWS. An adversary could gain backdoor access via SAML.
references:
    - https://docs.aws.amazon.com/IAM/latest/APIReference/API_UpdateSAMLProvider.html
    - https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithSAML.html
author: Austin Songer
date: 2021-09-22
modified: 2022-12-18
tags:
    - attack.initial-access
    - attack.lateral-movement
    - attack.persistence
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1078
    - attack.t1548
    - attack.t1550
    - attack.t1550.001
logsource:
    product: aws
    service: cloudtrail
detection:
    selection_sts:
        eventSource: 'sts.amazonaws.com'
        eventName: 'AssumeRoleWithSAML'
    selection_iam:
        eventSource: 'iam.amazonaws.com'
        eventName: 'UpdateSAMLProvider'
    condition: 1 of selection_*
falsepositives:
    - Automated processes that uses Terraform may lead to false positives.
    - SAML Provider could be updated by a system administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
    - SAML Provider being updated from unfamiliar users should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
level: medium

Original YAML and metadata in JSON

False positives

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

Source references

• https://docs.aws.amazon.com/IAM/latest/APIReference/API_UpdateSAMLProvider.html
• https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithSAML.html