Suspicious Modification Of Scheduled Tasks

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About the rule

Rule Type

Standard

Rule Description

Detects when an attacker tries to modify an already existing scheduled tasks to run from a suspicious location Attackers can create a simple looking task in order to avoid detection on creation as it's often the most focused on Instead they modify the task after creation to include their malicious payload

Severity

Trouble

Rule Requirement

Criteria

Action1: actionname = "Process started" AND (PROCESSNAME endswith "\schtasks.exe" AND (COMMANDLINE contains " /Change " AND COMMANDLINE contains " /TN ")) AND COMMANDLINE contains "\AppData\Local\Temp,\AppData\Roaming\,\Users\Public\,\WINDOWS\Temp\,\Desktop\,\Downloads\,\Temporary Internet,C:\ProgramData\,C:\Perflogs\,%ProgramData%,%appdata%,%comspec%,%localappdata%" AND COMMANDLINE contains "regsvr32,rundll32,cmd /c ,cmd /k ,cmd /r ,cmd.exe /c ,cmd.exe /k ,cmd.exe /r ,powershell,mshta,wscript,cscript,certutil,bitsadmin,bash.exe,bash ,scrcons,wmic ,wmic.exe,forfiles,scriptrunner,hh.exe,hh " 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)