Azure Application Security Group Modified or Deleted via Activity Log Write/Delete

title: Azure Application Security Group Modified or Deleted via Activity Log Write/Delete
id: 37c63290-5824-4ab3-8cd8-6d61db307532
status: test
description: This rule flags Azure Activity Log events where an Application Security Group is modified (WRITE) or removed (DELETE). Attackers can tamper with ASG rules or delete the group to disrupt network access controls, potentially enabling lateral movement or weakening exposure. The detection relies on Azure Activity Log telemetry capturing operation names for APPLICATIONSECURITYGROUPS write and delete actions.
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_application_security_group_modified_or_deleted.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.NETWORK/APPLICATIONSECURITYGROUPS/WRITE
      - MICROSOFT.NETWORK/APPLICATIONSECURITYGROUPS/DELETE
  condition: selection
falsepositives:
  - Application security group being modified or deleted may be performed by a system administrator.
  - Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
  - Application security group modified or deleted 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: 835747f1-9329-40b5-9cc3-97d465754ce6
    type: derived