full-disclosure - [FD] Backdoor.Win32.RemoteManipulator.brr / Insecure Permissions EoP

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Date: Tue, 2 Feb 2021 22:27:29 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.RemoteManipulator.brr / Insecure Permissions EoP

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/717f316391b6a7b97fa160b0a627a413.txt
Contact: malvuln13@...il.com
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

Disclaimer: The information contained within this advisory is supplied
"as-is" with no warranties or guarantees of fitness of use or
otherwise. Permission is hereby granted for the redistribution of this
advisory, provided that it is not altered except by reformatting it,
and that due credit is given. Permission is explicitly given for
insertion in vulnerability databases and similar, provided that due
credit is given to the author. The author is not responsible for any
misuse of the information contained herein and accepts no
responsibility for any damage caused by the use or misuse of this
information. The author prohibits any malicious use of security
related information or exploits by the author or elsewhere. Do not
attempt to download Malware samples. The author of this website takes
no responsibility for any kind of damages occurring from improper
Malware handling or the downloading of ANY Malware mentioned on this
website or elsewhere. All content Copyright (c) Malvuln.com (TM).

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