Trojan-Downloader.Win32.Delf.nzg Insecure Permissions

`Discovery / credits: Malvuln - malvuln.com (c) 2021  
Original source: https://malvuln.com/advisory/3c5c6f0f6f78af12d6b76119696a4074.txt  
Contact: [email protected]  
Media: twitter.com/malvuln  
  
Threat: Trojan-Downloader.Win32.Delf.nzg  
Vulnerability: Insecure Permissions  
Description: Win32.Delf.nzg creates an insecure dir named "Arquivos de Programas" 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: 3c5c6f0f6f78af12d6b76119696a4074  
Vuln ID: MVID-2021-0157  
Dropped files: npdsplay2.dll, Update.exe   
Disclosure: 04/01/2021  
  
Exploit/PoC:  
:\>cacls "Arquivos de Programas"  
C:\Arquivos de Programas 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 "Arquivos de Programas"  
  
C:\Arquivos de Programas>dir "Windows Media Player"  
Volume in drive C has no label.  
  
Directory of C:\Arquivos de Programas\Windows Media Player  
  
03/31/2021 08:49 PM 0 npdsplay2.dll  
1 File(s) 0 bytes  
  
C:\Arquivos de Programas>dir WindowsUpdate  
Volume in drive C has no label.  
  
Directory of C:\Arquivos de Programas\WindowsUpdate  
  
03/31/2021 08:49 PM 198,144 Update.exe  
1 File(s) 198,144 bytes  
  
  
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