full-disclosure - [FD] Backdoor.Win32.Cyn.20 / Insecure Permissions

Open Source and information security mailing list archives

Message-ID: <CAAHK0WR+AwpFo2OUk0izxigdcxJ98obniFiCOUhu+szkz6oWdg@mail.gmail.com>
Date: Fri, 25 Mar 2022 21:52:01 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Cyn.20 / Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source:
https://malvuln.com/advisory/3dd1da64e306cae0409e154e15dd1b80.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Cyn.20
Vulnerability: Insecure Permissions
Description: The malware writes a ".EXE" file with insecure permissions to
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.
Family: Cyn
Type: PE32
MD5: 3dd1da64e306cae0409e154e15dd1b80
Vuln ID: MVID-2022-0524
Disclosure: 03/25/2022

Exploit/PoC:
C:\>cacls "Program Filessystem.EXE"
C:\Program Filessystem.EXE BUILTIN\Administrators:(ID)F
                           NT AUTHORITY\SYSTEM:(ID)F
                           BUILTIN\Users:(ID)R
                           NT AUTHORITY\Authenticated Users:(ID)C

C:\>dir "Program Filessystem.EXE"
 Volume in drive C has no label.

 Directory of C:\

03/22/2022  02:35 AM                 0 Program Filessystem.EXE
               1 File(s)              0 bytes
               0 Dir(s)  24,893,874,176 bytes free

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: https://seclists.org/fulldisclosure/

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives