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InformationalSplunk security contentTeoderick Contreras +1

Windows Rundll32 with Non-Standard File Extension

This analytic identifies the instance of rundll32.exe process loading a non-standard Windows modules file extension. This behavior is not common and can be associated with malicious activities, such as the Gh0st RAT…

Description

This analytic identifies the instance of rundll32.exe process loading a non-standard Windows modules file extension. This behavior is not common and can be associated with malicious activities, such as the Gh0st RAT backdoor. This technique is to evade possible detection by security tools that monitors a suspicious dll loading activity.

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
crowdstrike_processrollup2sysmon_eventid_1windows_event_log_security_4688

Known benign triggers

  • Certain legitimate Windows components, third-party applications, or administrative scripts may use rundll32.exe with non-standard or extensionless inputs during normal operation. Filtering and contextual analysis are required, focus on command-line arguments, parent process, file location, and prevalence across the environment before determining malicious intent.

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