Detection rules › Sigma

Potential Mpclient.DLL Sideloading Via OfflineScannerShell.EXE Execution

Severity
medium
Author
frack113
Source
upstream

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.

MITRE ATT&CK coverage

TacticTechniques
Defense EvasionT1218 System Binary Proxy Execution

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation

Stages and Predicates

Stage 1: selection

or:
Image|endswith: '\OfflineScannerShell.exe'
OriginalFileName: OfflineScannerShell.exe

Stage 2: not 1 of filter_main_*

or:
CurrentDirectory: ''
CurrentDirectory: 'C:\Program Files\Windows Defender\Offline\'
CurrentDirectory: null

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CurrentDirectoryeq
  • C:\Program Files\Windows Defender\Offline\
Imageends_with
  • \OfflineScannerShell.exe
OriginalFileNameeq
  • OfflineScannerShell.exe