Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/e184abe44bec183a522d2c66bc3f90e0.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Packed.Win32.Katusha.o (Ransomeware)
Vulnerability: Insecure Permissions EoP
Description: The malware create two dirs, one of them under the users home dir. The files dropped are hidden and can be viewed using dir /a command. Then after about 35 secs locks the victims screen, issuing a warning about pirated software and to pay in BTC. If not paid, a warrant will be issued for arrest. However, the malware grants full (F) permissions to everyone for the "bkkYoIYg" dir under that targets users home dir.

C:\>cacls C:\Users\VICTIM\bkkYoIYg\BkkMEYcs.exe
C:\Users\VICTIM\bkkYoIYg\BkkMEYcs.exe No permissions are set. All user have full control

Type: PE32
MD5: e184abe44bec183a522d2c66bc3f90e0
Vuln ID: MVID-2021-0061
Dropped files: BkkMEYcs.exe, BkkMEYcs, BkkMEYcs.inf, C:\ProgramData\HcgIwoAM\DiAYIoQI.exe, DiAYIoQI.inf
Disclosure: 01/28/2021


Exploit/PoC:
1) switch user to standard user for PoC
2) open taskmgr kill the malware
3) now you are able to place any files under the vuln "bkkYoIYg" dir under the privileged users home dir.


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