Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/35cf54a19efcdeaa41899647075c7ef9.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Agent.bjev
Vulnerability: Insecure Permissions
Description: Agent.bjev creates an insecure dir named "Windupdt" under c:\ drive, granting change permissions (C) to the authenticated user group. Standard users can rename the malware to disable it or replace with their own executable. Then wait for a privileged user to logon to the infected machine to potentially escalate privileges.
Type: PE32
MD5: 35cf54a19efcdeaa41899647075c7ef9
Vuln ID: MVID-2021-0123
Dropped files: winupdate.exe
Disclosure: 03/06/2021

Exploit/PoC:
C:\>cacls \Windupdt
C:\Windupdt BUILTIN\Administrators:(OI)(CI)(ID)F
            NT AUTHORITY\SYSTEM:(OI)(CI)(ID)F
            BUILTIN\Users:(OI)(CI)(ID)R
            NT AUTHORITY\Authenticated Users:(ID)C
            NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C

C:\Windupdt>dir /a
 Volume in drive C has no label.

 Directory of C:\Windupdt

06/17/2012  12:16 AM           974,848 winupdate.exe
               1 File(s)        974,848 bytes


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