Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/dec17541412bbc744b9f458862349e34.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Nyara.aq
Vulnerability: Insecure Permissions
Description: The malware creates a dir with insecure permissions under c:\ drive and grants 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: dec17541412bbc744b9f458862349e34
Vuln ID: MVID-2021-0335
Dropped files: Update.exe
Disclosure: 09/06/2021


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

 Directory of C:\System

06/17/2012  01:53 AM           774,144 Update.exe
               1 File(s)        774,144 bytes


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