full-disclosure - [FD] Backdoor.Win32.GTbot.c / Insecure Permissions

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Message-ID: <CAAHK0WRnhxocGmakQpjhowPRfQUzquGPb97C6nbhoSivjsWdPg@mail.gmail.com>
Date: Sat, 6 Mar 2021 19:32:22 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.GTbot.c / Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/8c2acfcc60dda52db9bd9a934284b673.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.GTbot.c
Vulnerability: Insecure Permissions
Description: GTbot creates an insecure dir called "WINNT" under c:\ drive
and grants 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: 8c2acfcc60dda52db9bd9a934284b673
Vuln ID: MVID-2021-0122
Dropped files: esman.exe, seman.exe
Disclosure: 03/06/2021

Exploit/PoC:
C:\>cacls WINNT
C:\WINNT 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:\>cd WINNT

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

 Directory of C:\WINNT

03/02/2021  07:44 K0L4B0R451    <DIR>          SYSTEM32
               0 File(s)              0 bytes
               3 Dir(s)  57,185,968,128 bytes free

C:\WINNT>cd SYSTEM32

C:\WINNT\SYSTEM32>dir
 Volume in drive C has no label.

 Directory of C:\WINNT\SYSTEM32

04/26/2006  12:06 K0L4B0R451            33,100 esman.exe
04/26/2006  12:07 K0L4B0R451            20,408 seman.exe
               2 File(s)         53,508 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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