Detection rules › Sigma

Activity Performed by Terminated User

Status
test
Severity
medium
Log source
product m365, service threat_management
Author
Austin Songer @austinsonger
Source
github.com/SigmaHQ/sigma

Detects when a Microsoft Cloud App Security reported for users whose account were terminated in Azure AD, but still perform activities in other platforms such as AWS or Salesforce. This is especially relevant for users who use another account to manage resources, since these accounts are often not terminated when a user leaves the company.

MITRE ATT&CK coverage

TacticTechniques
ImpactNo specific technique

Rule body yaml

title: Activity Performed by Terminated User
id: 2e669ed8-742e-4fe5-b3c4-5a59b486c2ee
status: test
description: |
  Detects when a Microsoft Cloud App Security reported for users whose account were terminated in Azure AD, but still perform activities in other platforms such as AWS or Salesforce.
  This is especially relevant for users who use another account to manage resources, since these accounts are often not terminated when a user leaves the company.
references:
    - https://learn.microsoft.com/en-us/defender-cloud-apps/anomaly-detection-policy
    - https://learn.microsoft.com/en-us/defender-cloud-apps/policy-template-reference
author: Austin Songer @austinsonger
date: 2021-08-23
modified: 2022-10-09
tags:
    - attack.impact
logsource:
    service: threat_management
    product: m365
detection:
    selection:
        eventSource: SecurityComplianceCenter
        eventName: 'Activity performed by terminated user'
        status: success
    condition: selection
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    eventSource: SecurityComplianceCenter
    eventName: 'Activity performed by terminated user'
    status: success

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
  • Activity performed by terminated user
eventSourceeq
  • SecurityComplianceCenter
statuseq
  • success