full-disclosure - [FD] Backdoor.Win32.Neakse.bit / Insecure Permissions

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Message-ID: <CAAHK0WSX2KjToEfSt_K=-9AM7TGniCwynDcB-GA7Z+=yAEpmOQ@mail.gmail.com>
Date: Sun, 6 Jun 2021 22:40:29 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Neakse.bit / Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/20863ba09c31037b1b3220fc6da100e1.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Neakse.bit
Vulnerability: Insecure Permissions
Description: The malware creates two insecure dirs housing DLLs under c:\
drive and grants change (C) permissions to the authenticated user group.
Standard users can rename the executables dropped by the malware to disable
it or replace it with their own executable. Then wait for a privileged user
to logon to the infected machine to potentially escalate privileges.
Type: PE32
MD5: 20863ba09c31037b1b3220fc6da100e1
Vuln ID: MVID-2021-0238
Disclosure: 06/06/2021

Exploit/PoC:
C:\>cacls codecs
C:\codecs 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:\>dir codecs
 Volume in drive C has no label.

 Directory of C:\codecs

04/06/2004  12:04 AM           548,919 colorcvt.dll
04/06/2004  12:05 AM            65,602 cook.dll
04/06/2004  12:07 AM           266,306 erv3.dll
04/06/2004  12:08 AM           479,298 erv4.dll
04/06/2004  12:05 AM           155,702 ralf.dll
04/06/2004  12:05 AM           102,465 sipr.dll
               6 File(s)      1,618,292 bytes

C:\>cacls common
C:\common 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:\>dir common
 Volume in drive C has no label.

 Directory of C:\common

12/06/2002  02:02 PM           395,776 encn3260.dll
04/06/2004  12:08 AM           368,732 rembrdcst.dll
               2 File(s)        764,508 bytes

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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