Sunturai
Back to results
MediumSplunk security contentRod SotoThreat hunting

MCP Filesystem Server Suspicious Extension Write

This detection identifies attempts to create executable or script files through MCP filesystem server connections. Threat actors leveraging LLM-based tools may attempt to write malicious executables, scripts, or…

Description

This detection identifies attempts to create executable or script files through MCP filesystem server connections. Threat actors leveraging LLM-based tools may attempt to write malicious executables, scripts, or batch files to disk for persistence or code execution. The detection prioritizes files written to system directories or startup locations which indicate higher likelihood of malicious intent.

Detection logic

Detection requirements

Platform
ContainersESXiIaaSIdentity ProviderLinuxmacOSNetwork DevicesOffice SuiteSaaSWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Log source category
mcp_server

Known benign triggers

  • Legitimate developers using LLM assistants to generate scripts or automation tools, DevOps engineers creating deployment scripts, and system administrators generating batch files for maintenance tasks.

Detections can measure how the public catalogue is used — which detections people look for, and which pages bring them here. It sets a cookie that recognises this browser for 180 days. It is never linked to an account and never follows you to other sites. Privacy notice