Potential Mpclient.DLL Sideloading Via OfflineScannerShell.EXE Execution

SIGMA detection rule by frack113 · NOASSERTION

Detects execution of Windows Defender "OfflineScannerShell.exe" from its non standard directory. The "OfflineScannerShell.exe" binary is vulnerable to DLL side loading and will load any DLL named "mpclient.dll" from the current working directory.

title: Potential Mpclient.DLL Sideloading Via OfflineScannerShell.EXE Execution
id: 02b18447-ea83-4b1b-8805-714a8a34546a
status: test
description: |
    Detects execution of Windows Defender "OfflineScannerShell.exe" from its non standard directory.
    The "OfflineScannerShell.exe" binary is vulnerable to DLL side loading and will load any DLL named "mpclient.dll" from the current working directory.
references:
    - https://lolbas-project.github.io/lolbas/Binaries/OfflineScannerShell/
author: frack113
date: 2022-03-06
modified: 2023-08-03
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - Image|endswith: '\OfflineScannerShell.exe'
        - OriginalFileName: 'OfflineScannerShell.exe'
    filter_main_legit_dir:
        CurrentDirectory: 'C:\Program Files\Windows Defender\Offline\'
    filter_main_empty:
        CurrentDirectory: ''
    filter_main_null:
        CurrentDirectory: null
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

c5ecafe5-7e9c-4ae6-ae8c-a2258c74b9a0

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

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Format & documentation suggestions

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

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