359. Hunting for Suspicious File Deletion Events

Hello everyone!

As you know, adversaries may delete malicious files and tools for defense evasion. But can we use it for threat hunting? Let's find out!

We need an example, of course. Let's look at Amadey loader described in this report. The adversary leveraged multiple commands to delete existing malicious file and move a copy to a different location:

cmd.exe /k "taskkill /f /im "Yfgfwb.exe" && timeout 1 && del "Yfgfwb.exe" && ren 07072f Yfgfwb.exe && C:\Users\UserName\Appdata\Local\Temp\067640a009\Yfgfwb.exe && Exit

For example, we can look for sequences of suspicious commands, like taskkill and del:

event_type: "processcreatewin"

AND

proc_file_path: "cmd.exe"

AND

cmdline: ("taskkill" AND "del")

See you tomorrow!

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