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NetSh Helper DLL
Persistence, code execution using netsh helper arbitrary libraries.
NetshHelperBeacon helper DLL will be used to test out this technique. A compiled x64 DLL can be downloaded below:
NetshHelperBeacon.dll
43KB
Binary
NetshHelperBeacon
The helper library, once loaded, will start
calc.exe:
attacker@victim
.\netsh.exe add helper C:\tools\NetshHelperBeacon.dll
Adding a new helper via commandline modifies registry, so as a defender you may want to monitor for registry changes in
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NetSh:
When netsh is started, Procmon captures how
InitHelperDLL expored function of our malicious DLL is called:
As usual, monitoring command line arguments is a good idea that may help uncover suspicious activity:
Loading the malicious helper DLL crashed netsh. Inspecting the calc.exe process after the crash with Process Explorer reveals that the parent process is svchost, although the sysmon logs showed cmd.exe as its parent:
Last modified 5yr ago