Files With System DLL Name In Unsuspected Locations

Last updated on:

About the rule

Rule Type

Standard

Rule Description

Detects the creation of a file with the ".dll" extension that has the name of a System DLL in uncommon or unsuspected locations. (Outisde of "System32", "SysWOW64", etc.). It is highly recommended to perform an initial baseline before using this rule in production.

Severity

Trouble

Rule Requirement

Criteria

Action1: actionname = "File Created or Modified" AND (FILENAME endswith "\secur32.dll,\tdh.dll" OR OBJECTNAME endswith "\secur32.dll,\tdh.dll") AND (FILENAME notcontains "C:\$WINDOWS.~BT\,C:\$WinREAgent\,C:\Windows\SoftwareDistribution\,C:\Windows\System32\,C:\Windows\SysWOW64\,C:\Windows\WinSxS\,C:\Windows\uus" AND OBJECTNAME notcontains "C:\$WINDOWS.~BT\,C:\$WinREAgent\,C:\Windows\SoftwareDistribution\,C:\Windows\System32\,C:\Windows\SysWOW64\,C:\Windows\WinSxS\,C:\Windows\uus") select Action1.HOSTNAME,Action1.MESSAGE,Action1.USERNAME,Action1.DOMAIN,Action1.OBJECTNAME,Action1.FILENAME,Action1.PROCESSNAME

Detection

Execution Mode

realtime

Log Sources

Windows

Author

Nasreddine Bencherchali (Nextron Systems)