Change User Agents with WebRequest — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: medium. Source dates: 2022-01-23 / 2025-07-18.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 8b4b764124078f74ed045f5bfb1e33c6613c345da6126b8b904b5d7d71f6e5d8

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Change User Agents with WebRequest
id: d4488827-73af-4f8d-9244-7b7662ef046e
status: test
description: |
    Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic.
    Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1071.001/T1071.001.md#t1071001---web-protocols
author: frack113
date: 2022-01-23
modified: 2025-07-18
tags:
    - attack.command-and-control
    - attack.t1071.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_webrequest:
        ScriptBlockText|contains:
            - 'Invoke-WebRequest'
            - 'Invoke-RestMethod'
            - ' irm ' # Space before and after to avoid false positives with 'irm' as a variable
            - 'iwr '
    selection_useragent:
        ScriptBlockText|contains: '-UserAgent '
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1071.001/T1071.001.md#t1071001---web-protocols