Azure Application Security Group Modified or Deleted via Activity Logs

Flags Azure Activity Log events showing Application Security Group write (modify) or delete operations.

FreeUnreviewedSigmamediumv1

azure-application-security-group-modified-or-deleted-via-activity-logs-835747f1

title: Azure Application Security Group Modified or Deleted via Activity Logs
id: 37c63290-5824-4ab3-8cd8-6d61db307532
status: test
description: This rule identifies Azure Activity Log events where an Application Security Group (ASG) is written (modified) or deleted. Attackers and misusers may alter ASG rules or remove them to weaken network access controls or disrupt connectivity. The detection relies on Azure Activity Log entries with specific operation names for ASG 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

What it detects

This rule identifies Azure Activity Log events where an Application Security Group (ASG) is written (modified) or deleted. Attackers and misusers may alter ASG rules or remove them to weaken network access controls or disrupt connectivity. The detection relies on Azure Activity Log entries with specific operation names for ASG write and delete actions.

Known false positives

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.

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.