Detection rules › Sigma

AWS Suspicious SAML Activity

Status
test
Severity
medium
Log source
product aws, service cloudtrail
Author
Austin Songer
Source
github.com/SigmaHQ/sigma

Identifies when suspicious SAML activity has occurred in AWS. An adversary could gain backdoor access via SAML.

MITRE ATT&CK coverage

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

Rule body yaml

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

Stages and Predicates

Stage 0: condition

1 of selection_*

Stage 1: selection_sts

selection_sts:
    eventSource: 'sts.amazonaws.com'
    eventName: 'AssumeRoleWithSAML'

Stage 2: selection_iam

selection_iam:
    eventSource: 'iam.amazonaws.com'
    eventName: 'UpdateSAMLProvider'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
eventNameeq
  • AssumeRoleWithSAML
  • UpdateSAMLProvider
eventSourceeq
  • iam.amazonaws.com
  • sts.amazonaws.com