Azure Activity Logs: Alert Suppression Rule Write Operations

title: "Azure Activity Logs: Alert Suppression Rule Write Operations"
id: 94fcf510-1d29-4c20-9bb1-87752d811232
status: test
description: This rule flags creation of Azure Security alert suppression rules by matching activity log events where operationName is MICROSOFT.SECURITY/ALERTSSUPPRESSIONRULES/WRITE. Attackers may use this capability to reduce visibility by suppressing alerts tied to specific conditions. The detection relies on Azure Activity Logs telemetry and the operationName field indicating the suppression rule write action.
references:
  - https://learn.microsoft.com/en-us/azure/role-based-access-control/resource-provider-operations
  - https://github.com/SigmaHQ/sigma/blob/master/rules/cloud/azure/activity_logs/azure_suppression_rule_created.yml
author: Austin Songer, Huntrule Team
date: 2021-08-16
modified: 2022-08-23
tags:
  - attack.impact
logsource:
  product: azure
  service: activitylogs
detection:
  selection:
    operationName: MICROSOFT.SECURITY/ALERTSSUPPRESSIONRULES/WRITE
  condition: selection
falsepositives:
  - Suppression Rule being created may be performed by a system administrator.
  - Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
  - Suppression Rule created from unfamiliar users should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
level: medium
license: DRL-1.1
related:
  - id: 92cc3e5d-eb57-419d-8c16-5c63f325a401
    type: derived