125. Hunting for More_eggs Backdoor

Hello everyone!

Yesterday we talked about some new tools developed by the threat actor known as Venom Spider. But let's talk a bit about some classic tools he's known for. I mean more_eggs backdoor. It's still used, for example, here's a fresh campaign covered by Arctic Wolf.

I want to point out the following behavior marker - msxsl.exe, a legitimate binary known as Microsoft’s Command Line Transformation Utility, is used to execute the backdoor:

msxsl.exe D30F38D93CA9185.txt D30F38D93CA9185.txt

We can use this marker to build our hunting query:

event_type: "processcreatewin"

AND

proc_file_name: "msxsl.exe"

AND

cmdline: "txt"

Have you observed msxsl.exe in your environment?

See you tomorrow!

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