Azure Firewall rule collections and groups modified or deleted via Activity Logs

Flags Azure Activity Log write/delete operations that modify or delete firewall rule groups or rule collection groups.

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azure-firewall-rule-collections-and-groups-modified-or-deleted-via-activity-logs-2a7d64cf

title: Azure Firewall rule collections and groups modified or deleted via Activity Logs
id: 5a0cffc6-9865-4aad-b08a-cbdfad810aee
status: test
description: This rule identifies Azure Activity Log events where firewall rule configurations are modified or deleted, including write and delete operations for rule collection groups and rule groups. Attackers may alter or remove firewall rules to bypass network controls, disrupt traffic filtering, or expose otherwise protected services. The detection relies on Azure Activity Log operationName telemetry indicating the specific firewall rule configuration write/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_network_firewall_rule_modified_or_deleted.yml
author: Austin Songer @austinsonger, Huntrule Team
date: 2021-08-08
modified: 2022-08-23
tags:
  - attack.impact
logsource:
  product: azure
  service: activitylogs
detection:
  selection:
    operationName:
      - MICROSOFT.NETWORK/FIREWALLPOLICIES/RULECOLLECTIONGROUPS/WRITE
      - MICROSOFT.NETWORK/FIREWALLPOLICIES/RULECOLLECTIONGROUPS/DELETE
      - MICROSOFT.NETWORK/FIREWALLPOLICIES/RULEGROUPS/WRITE
      - MICROSOFT.NETWORK/FIREWALLPOLICIES/RULEGROUPS/DELETE
  condition: selection
falsepositives:
  - Firewall Rule Configuration 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.
  - Firewall Rule Configuration 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: 2a7d64cf-81fa-4daf-ab1b-ab80b789c067
    type: derived

What it detects

This rule identifies Azure Activity Log events where firewall rule configurations are modified or deleted, including write and delete operations for rule collection groups and rule groups. Attackers may alter or remove firewall rules to bypass network controls, disrupt traffic filtering, or expose otherwise protected services. The detection relies on Azure Activity Log operationName telemetry indicating the specific firewall rule configuration write/delete actions.

Known false positives

Firewall Rule Configuration 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.
Firewall Rule Configuration 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.