Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/001fc372acc853aa1cf92588a43a7deb.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Virus.Win32.Renamer.a
Vulnerability: Insecure Permissions
Description: The malware creates an dir with insecure permissions under c:\ drive granting change (C) permissions to the authenticated user group. Standard users can rename the executable 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: 001fc372acc853aa1cf92588a43a7deb 
Vuln ID: MVID-2021-0352
Dropped files: GUESSNUM.EXE
Disclosure: 10/04/2021


Exploit/PoC:
C:\>cacls "RECYCLER.{645FF040-5081-101B-9F08-00AA002F954E}"
C:\RECYCLER.{645FF040-5081-101B-9F08-00AA002F954E} 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 /a "RECYCLER.{645FF040-5081-101B-9F08-00AA002F954E}"
 Volume in drive C has no label.

 Directory of C:\RECYCLER.{645FF040-5081-101B-9F08-00AA002F954E}

06/17/2012  06:06 AM           818,211 GUESSNUM.EXE
               1 File(s)        818,211 bytes


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