sigmaDRL-1.1from SigmaHQ/sigma

Change User Agents with WebRequest

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.

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ATT&CK techniques

T1071.001

Rule sourcerules/windows/powershell/powershell_script/posh_ps_susp_invoke_webrequest_useragent.yml

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