Backdoor.Win32.GTbot.c / Insecure Permissions

[malvuln <malvuln13 () gmail com>]

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



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