272. Here's Another Interesting Staging Folder You Can Use for Hunting

Hello everyone!

As you know, in some cases adversaries choose very interesting staging folders to store their toolset on the compromised system. This fact, of course, may provide us hunting opportunities!

Let's look at CountLoader. According to the report, it has the folowing capabilities among others:

  • Download a file to the %userprofile%\Music\ directory and execute it.
  • Download a DLL to the %userprofile%\Music\ directory and execute it with rundll32.exe.
  • Download an MSI file to the %userprofile%\Music\ directory and execute it with msiexec.exe.

First, we can hunt for any executions from Music folder:

event_type: "processcreatewin"

AND

proc_file_path: "music"

Second, we can hunt for rundll32.exe or msiexec.exe executing suspicious files from Music folder:

event_type: "processcreatewin"

AND

proc_file_path: ("rundll32.exe" OR "msiexec.exe")

AND

cmdline: "music"

See you tomorrow!

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