Windows PowerShell Add Module to Global Assembly Cache
The following analytic detects the addition of a DLL to the Windows Global Assembly Cache (GAC) using PowerShell. It leverages PowerShell Script Block Logging to identify commands containing…
Description
The following analytic detects the addition of a DLL to the Windows Global Assembly Cache (GAC) using PowerShell. It leverages PowerShell Script Block Logging to identify commands containing "system.enterpriseservices.internal.publish". This activity is significant because adding a DLL to the GAC allows it to be shared across multiple applications, potentially enabling an adversary to execute malicious code system-wide. If confirmed malicious, this could lead to widespread code execution, privilege escalation, and persistent access across the operating system, posing a severe security risk.
Detection logic
Detection requirements
- Platform
- Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- powershell_script_block_logging_4104
Known benign triggers
- False positives may be present based on developers or third party utilities adding items to the GAC.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| www.microsoft.com/en-us/security/blog/2022/07/26/malicious-iis-extensions-quietly-open-persistent-backdoors-into-servers/ | 4from 2 sources |
| www.microsoft.com/en-us/security/blog/2022/12/12/iis-modules-the-evolution-of-web-shells-and-how-to-detect-them/ | 11from 2 sources |
From the source
- At source
- Open at source
- Upstream identifier
- 3fc16961-97e5-4a5b-a079-e4ab0d9763eb
- Tagged by the source as
- IIS ComponentsEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1