Change Default File Association To Executable Via Assoc
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About the rule
Rule Type
Standard
Rule Description
Detects when a program changes the default file association of any extension to an executable. When a file is opened, the default program used to open the file (also called the file association or handler) is checked. File association selections are stored in the Windows Registry and can be edited by users, administrators, or programs that have Registry access or by administrators using the built-in assoc utility. Applications can modify the file association for a given file extension to call an arbitrary program when a file with the given extension is opened.
Severity
Trouble
Rule Requirement
Criteria
Action1: actionname = "Process started" AND ((PROCESSNAME endswith "\cmd.exe" OR ORIGINALFILENAME = "Cmd.Exe") AND (COMMANDLINE contains "assoc " AND COMMANDLINE contains "exefile")) AND COMMANDLINE notcontains ".exe=exefile" select Action1.HOSTNAME,Action1.MESSAGE,Action1.COMMANDLINE,Action1.FILE_NAME,Action1.PROCESSNAME,Action1.USERNAME,Action1.PARENTPROCESSNAME
Detection
Execution Mode
realtime
Log Sources
Windows
Author
Nasreddine Bencherchali (Nextron Systems)
