Azure Activity Logs: Virtual Network Device Modified or Deleted

Alerts on Azure Activity Log operations that write or delete virtual network devices such as NICs, virtual appliances, hubs, and routers.

FreeUnreviewedSigmamediumv1

azure-activity-logs-virtual-network-device-modified-or-deleted-15ef3fac

title: "Azure Activity Logs: Virtual Network Device Modified or Deleted"
id: 0d583be0-d77b-45b6-b8f4-2ebf3c31a0c2
status: test
description: This rule flags Azure Activity Log events where virtual network devices are written or deleted, including network interfaces, network virtual appliances, virtual hubs, and virtual routers. Attackers may abuse these operations to disrupt connectivity or alter network behavior within an Azure environment. It relies on Activity Log telemetry capturing specific Microsoft.Network operation names for write, delete, and related join/configuration actions, along with the associated actor information in the log event.
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_virtual_device_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/NETWORKINTERFACES/TAPCONFIGURATIONS/WRITE
      - MICROSOFT.NETWORK/NETWORKINTERFACES/TAPCONFIGURATIONS/DELETE
      - MICROSOFT.NETWORK/NETWORKINTERFACES/WRITE
      - MICROSOFT.NETWORK/NETWORKINTERFACES/JOIN/ACTION
      - MICROSOFT.NETWORK/NETWORKINTERFACES/DELETE
      - MICROSOFT.NETWORK/NETWORKVIRTUALAPPLIANCES/DELETE
      - MICROSOFT.NETWORK/NETWORKVIRTUALAPPLIANCES/WRITE
      - MICROSOFT.NETWORK/VIRTUALHUBS/DELETE
      - MICROSOFT.NETWORK/VIRTUALHUBS/WRITE
      - MICROSOFT.NETWORK/VIRTUALROUTERS/WRITE
      - MICROSOFT.NETWORK/VIRTUALROUTERS/DELETE
  condition: selection
falsepositives:
  - Virtual Network Device 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.
  - Virtual Network Device 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: 15ef3fac-f0f0-4dc4-ada0-660aa72980b3
    type: derived

What it detects

This rule flags Azure Activity Log events where virtual network devices are written or deleted, including network interfaces, network virtual appliances, virtual hubs, and virtual routers. Attackers may abuse these operations to disrupt connectivity or alter network behavior within an Azure environment. It relies on Activity Log telemetry capturing specific Microsoft.Network operation names for write, delete, and related join/configuration actions, along with the associated actor information in the log event.

Known false positives

Virtual Network Device 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.
Virtual Network Device 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.