Regsvr32.EXE Calling of DllRegisterServer Export Function Implicitly
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In this page
About the rule
Rule Type
Standard
Rule Description
Detects execution of regsvr32 with the silent flag and no other flags on a DLL located in an uncommon or potentially suspicious location. When Regsvr32 is called in such a way, it implicitly calls the DLL export function 'DllRegisterServer'.
Severity
Trouble
Rule Requirement
Criteria
Action1: actionname = "Process started" AND ((PROCESSNAME endswith "\regsvr32.exe" OR ORIGINALFILENAME = "REGSVR32.EXE") AND COMMANDLINE contains " /s , /e ") AND ((COMMANDLINE notcontains ":\Program Files (x86),:\Program Files\,:\Windows\System32\,:\Windows\SysWOW64" AND CWD notcontains ":\Program Files (x86),:\Program Files\,:\Windows\System32\,:\Windows\SysWOW64") AND COMMANDLINE notcontains " /i:,/U " AND (PARENTPROCESSCOMMANDLINE notendswith ":\Windows\System32\RpcProxy\RpcProxy.dll" OR COMMANDLINE != "regsvr32 /s rpcproxy.dll")) select Action1.HOSTNAME,Action1.MESSAGE,Action1.COMMANDLINE,Action1.FILE_NAME,Action1.PROCESSNAME,Action1.USERNAME,Action1.PARENTPROCESSNAME
Detection
Execution Mode
realtime
Log Sources
Windows
Author
Andreas Braathen (mnemonic.io), Nasreddine Bencherchali (Nextron Systems)
