Trojan-Downloader.Win32.Delf.nzg / Insecure Permissions

[malvuln <malvuln13 () gmail com>]

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/3c5c6f0f6f78af12d6b76119696a4074.txt
Contact: malvuln13 () gmail com
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


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).

_______________________________________________
Sent through the Full Disclosure mailing list
https://nmap.org/mailman/listinfo/fulldisclosure
Web Archives & RSS: http://seclists.org/fulldisclosure/