full-disclosure - [FD] Worm.Win32.Delf.hu / Insecure Permissions

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Message-ID: <CAAHK0WTRyrRDAsXfNuru=W7xk3FGXdsdK4eSheqq7gAxktNacQ@mail.gmail.com>
Date: Thu, 29 Apr 2021 19:05:04 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Worm.Win32.Delf.hu / Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/46e27d7bfdbda7a71dfa12a79026a88b.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Worm.Win32.Delf.hu
Vulnerability: Insecure Permissions
Description: The malware creates a hidden insecure dir named "RECYCLER"
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: 46e27d7bfdbda7a71dfa12a79026a88b
Vuln ID: MVID-2021-0192
Dropped ok.exe, REM.com
Disclosure: 04/29/2021

Exploit/PoC:
C:\>dir /a RECYCLER
 Volume in drive C has no label.

 Directory of C:\RECYCLER

06/16/2012  12:21 AM           449,024 ok.exe
06/16/2012  09:55 AM            61,952 REM.com
               2 File(s)        510,976 bytes
               2 Dir(s)  23,871,930,368 bytes free

C:\>cacls RECYCLER
C:\RECYCLER 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

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).

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