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Detection rules › Sigma

Proxy Execution Via Wuauclt.EXE

Status
test
Severity
high
Log source
category process_creation, product windows
Author
Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), Florian Roth (Nextron Systems), Sreeman, FPT.EagleEye Team
Source
github.com/SigmaHQ/sigma

Detects the use of the Windows Update Client binary (wuauclt.exe) for proxy execution.

MITRE ATT&CK coverage

TacticTechniques
Stealth

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Proxy Execution Via Wuauclt.EXE
id: af77cf95-c469-471c-b6a0-946c685c4798
related:
    - id: ba1bb0cb-73da-42de-ad3a-de10c643a5d0
      type: obsolete
    - id: d7825193-b70a-48a4-b992-8b5b3015cc11
      type: obsolete
status: test
description: Detects the use of the Windows Update Client binary (wuauclt.exe) for proxy execution.
references:
    - https://dtm.uk/wuauclt/
    - https://blog.malwarebytes.com/threat-intelligence/2022/01/north-koreas-lazarus-apt-leverages-windows-update-client-github-in-latest-campaign/
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), Florian Roth (Nextron Systems), Sreeman, FPT.EagleEye Team
date: 2020-10-12
modified: 2023-11-11
tags:
    - attack.stealth
    - attack.t1218
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\wuauclt.exe'
        - OriginalFileName: 'wuauclt.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'UpdateDeploymentProvider'
            - 'RunHandlerComServer'
    filter_main_generic:
        # Note: Please enhance this if you find the full path
        CommandLine|contains: ' /UpdateDeploymentProvider UpdateDeploymentProvider.dll '
    filter_main_wuaueng:
        # Note: Please enhance this if you find the full path
        CommandLine|contains: ' wuaueng.dll '
    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 '
    condition: all of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

all of selection_* and not 1 of filter_main_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\wuauclt.exe'
    - OriginalFileName: 'wuauclt.exe'

Stage 2: selection_cli

selection_cli:
    CommandLine|contains|all:
        - 'UpdateDeploymentProvider'
        - 'RunHandlerComServer'

Stage 3: not filter_main_*

filter_main_generic:
    CommandLine|contains: ' /UpdateDeploymentProvider UpdateDeploymentProvider.dll '
filter_main_wuaueng:
    CommandLine|contains: ' wuaueng.dll '
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 '

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
CommandLinematch:\Windows\WinSxS\excludes:CommandLine field:"CommandLine" value:":\Windows\WinSxS\"
CommandLinematch\UpdateDeploy.dll /ClassId excludes:CommandLine field:"CommandLine" value:"\UpdateDeploy.dll /ClassId "
CommandLinematch /UpdateDeploymentProvider UpdateDeploymentProvider.dll excludes:CommandLine field:"CommandLine" value:" /UpdateDeploymentProvider UpdateDeploymentProvider.dll "
CommandLinematch wuaueng.dll excludes:CommandLine field:"CommandLine" value:" wuaueng.dll "
CommandLinematch:\Windows\UUS\Packages\Preview\amd64\updatedeploy.dll /ClassIdexcludes:CommandLine field:"CommandLine" value:":\Windows\UUS\Packages\Preview\amd64\updatedeploy.dll /ClassId"
CommandLinematch:\Windows\UUS\amd64\UpdateDeploy.dll /ClassIdexcludes:CommandLine field:"CommandLine" value:":\Windows\UUS\amd64\UpdateDeploy.dll /ClassId"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • RunHandlerComServer
  • UpdateDeploymentProvider
field:"CommandLine" kind:match
Imageends_with
  • \wuauclt.exe corpus 3 (sigma 3)
field:"Image" kind:ends_with value:"\wuauclt.exe"
OriginalFileNameeq
  • wuauclt.exe corpus 5 (elastic 3, sigma 2)
field:"OriginalFileName" kind:eq value:"wuauclt.exe"