Wednesday, February 3, 2021

Backdoor.Win32.RemoteManipulator.brr Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/717f316391b6a7b97fa160b0a627a413.txt
Contact: [email protected]
Media: twitter.com/malvuln

Threat: Backdoor.Win32.RemoteManipulator.brr
Vulnerability: Insecure Permissions EoP
Description: This malware creates a dir named "eaKVB87.tmp" under c:\ and grants change (C) permissions to authenticated users group. This can result in EoP as any authenticated user can modify its dir.
Type: PE32
MD5: 717f316391b6a7b97fa160b0a627a413
Vuln ID: MVID-2021-0067
Dropped files: citoCavb.vbs, N0731337.bak, taskhosteo.exe, vp8encoder.dll
Disclosure: 02/02/2021


Exploit/PoC:
C:\>cacls C:\eaKVB87.tmp
C:\eaKVB87.tmp 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:\>cacls C:\eaKVB87.tmp\taskhosteo.exe
C:\eaKVB87.tmp\taskhosteo.exe BUILTIN\Administrators:(ID)F
NT AUTHORITY\SYSTEM:(ID)F
BUILTIN\Users:(ID)R
NT AUTHORITY\Authenticated Users:(ID)C

Directory of c:\eaKVB87.tmp

03/27/2017 01:38 AM 42,320 citoCavb.vbs
01/27/2021 08:36 PM 0 N0731337.bak
03/21/2017 08:11 PM 3,968,512 taskhosteo.exe
09/01/2016 07:44 AM 1,639,336 vp8encoder.dll


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