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Detection rules › Sigma

MMC Loading Script Engines DLLs

Status
experimental
Severity
medium
Log source
product windows, category image_load
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects when the Microsoft Management Console (MMC) loads the DLL libraries like vbscript, jscript etc which might indicate an attempt to execute malicious scripts within a trusted system process for bypassing application whitelisting or defense evasion.

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.005 Command and Scripting Interpreter: Visual Basic
StealthT1218.014 System Binary Proxy Execution: MMC

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: MMC Loading Script Engines DLLs
id: a9c73e8b-3b2d-4c45-8ef2-5f9a9c9998ad
status: experimental
description: |
    Detects when the Microsoft Management Console (MMC) loads the DLL libraries like vbscript, jscript etc which might indicate an attempt
    to execute malicious scripts within a trusted system process for bypassing application whitelisting or defense evasion.
references:
    - https://tria.ge/241015-l98snsyeje/behavioral2
    - https://www.elastic.co/security-labs/grimresource
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-02-05
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059.005
    - attack.t1218.014
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith: '\mmc.exe'
        ImageLoaded|endswith:
            - '\vbscript.dll'
            - '\jscript.dll'
            - '\jscript9.dll'
    condition: selection
falsepositives:
    - Legitimate MMC operations or extensions loading these libraries
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Image|endswith: '\mmc.exe'
    ImageLoaded|endswith:
        - '\vbscript.dll'
        - '\jscript.dll'
        - '\jscript9.dll'

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
Imageends_with
  • \mmc.exe corpus 5 (sigma 5)
ImageLoadedends_with
  • \jscript.dll corpus 2 (sigma 2)
  • \jscript9.dll
  • \vbscript.dll corpus 3 (sigma 3)