276. Hunting for Suspicious IIS Modules

Hello everyone!

Let's talk about another uncommon technique - Server Software Component: IIS Components (T1505.004), and how to hunt for installation of suspicious modules.

According to the report, UAT-8099 leveraged appcmd.exe to install and uninstall IIS modules:

c:\windows\System32\inetsrv\appcmd.exe uninstall module /module.name:HttpFastCgiModule

c:\windows\SysWOW64\inetsrv\appcmd.exe install module /name:HttpCgiModule /image:%windir%\SysWOW64\inetsrv\HttpCgiModule.dll /preCondition:bitness32

This behavior can be transformed into a hunting query:

event_type: "processcreatewin"

AND

proc_file_path: "appcmd.exe"

AND

cmdline: ("module" AND ("install" OR "uninstall"))

See you tomorrow!

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