offensive security
NetSh Helper DLL
Persistence, code execution using netsh helper arbitrary libraries.
Execution
​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:
Observations
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:
Interesting
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:
References
Event Triggered Execution: Netsh Helper DLL, Sub-technique T1546.007 - Enterprise | MITRE ATT&CK®
Last modified 3yr ago
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