Potentially Suspicious Wuauclt Network Connection (via network_connection)

title: Potentially Suspicious Wuauclt Network Connection (via network_connection)
id: 37a3e0ee-b47f-5642-a9e0-7000e2fe72e0
status: stable
description: This rule detects the use of the Windows Update Client binary (wuauclt.exe) to proxy execute code and making network connections. One could easily make the DLL spawn a new process and inject to it to proxy the network connection and bypass this rule.
references:
    - https://attack.mitre.org/techniques/T1218/
    - https://dtm.uk/wuauclt/
author: Huntrule Team
date: 2026-04-01
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: network_connection
    product: windows
    definition: 'Requirements: The CommandLine field enrichment is required in order for this rule to be used.'
detection:
    selection:
        Image|contains: 'wuauclt'
        CommandLine|contains: ' /RunHandlerComServer'
    filter_main_ip:
        DestinationIp|cidr:
            - '127.0.0.0/8'
            - '10.0.0.0/8'
            - '169.254.0.0/16'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '::1/128'
            - 'fe80::/10'
            - 'fc00::/7'
    filter_main_msrange:
        DestinationIp|cidr:
            - '20.184.0.0/13'
            - '20.192.0.0/10'
            - '23.79.0.0/16'
            - '51.10.0.0/15'
            - '51.103.0.0/16'
            - '51.104.0.0/15'
            - '52.224.0.0/11'
    filter_main_uus:
        CommandLine|contains:
            - ':\Windows\UUS\Packages\Preview\amd64\updatedeploy.dll /ClassId'
            - ':\Windows\UUS\amd64\UpdateDeploy.dll /ClassId'
    filter_main_winsxs:
        CommandLine|contains|all:
            - ':\Windows\WinSxS\'
            - '\UpdateDeploy.dll /ClassId '
    filter_main_cli_null:
        CommandLine:
    filter_main_cli_empty:
        CommandLine: ''
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium