361. That's How Adversaries Manipulate Volume Shadow Copy Service

Hello everyone!

It's not a secret that ransomware gangs often interact with Volume Shadow Copy Service to Inhibit System Recovery (T1490).

In most cases it's not a good target for hunting as adversaries abuse it on the latest stages of attack lifecycle. At the same time, they may use scripting to manipulate it, and it may be you last chance to detect malicious activity.

For example, Qilin executed the following commands:

cmd /C net start vss

cmd /C wmic service where name='vss' call ChangeStartMode Manual

cmd /C vssadmin.exe Delete Shadows /all /quiet

cmd /C net stop vss

cmd /C wmic service where name='vss' call ChangeStartMode Disabled

I'm sure you have detections for deletion, but what about manipulating the service? So, it may be a good idea to look for abusing wmic.exe for VSS manipulation:

event_type: "processcreatewin"

AND

proc_file_path: "wmic.exe"

AND

cmdline: "vss"

See you tomorrow!

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