full-disclosure - [FD] Backdoor.Win32.RemoteManipulator.fdo / Insecure Permissions

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Message-ID: <CAAHK0WRwnzBDLzoNNoaq29Erpw21ZakWwOTS4dQ4CnG3ohdqyg@mail.gmail.com>
Date: Mon, 1 Mar 2021 10:01:08 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.RemoteManipulator.fdo / Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/66ef21e8d1cf30dce6e084a9e306c18f.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.RemoteManipulator.fdo
Vulnerability: Insecure Permissions
Description: The backdoor creates an insecure randomly named hidden dir
with a .tmp ext E.g. 8RK86.tmp and grants change (C) permissions to the
authenticated user group. Standard users can rename the malware and reboot
to disable it or replace with their own executable to escalate privileges
when a privileged user logs on to the infected machine.
Type: PE32
MD5: 66ef21e8d1cf30dce6e084a9e306c18f
Vuln ID: MVID-2021-0116
Dropped files: settings.dat,  vp8encoder.dll, xpcomp.exe
Disclosure: 03/01/2021

Exploit/PoC:
C:\>cacls 4J83Z.tmp
C:\4J83Z.tmp 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 4J83Z.tmp

C:\4J83Z.tmp>dir
 Volume in drive C has no label.

 Directory of C:\4J83Z.tmp

File Not Found

C:\4J83Z.tmp>dir /a
 Volume in drive C has no label.

 Directory of C:\4J83Z.tmp

02/25/2021  05:55 PM             2,664 settings.dat
08/06/2017  06:51 AM           542,016 vp8encoder.dll
02/25/2021  05:55 PM         2,981,888 xpcomp.exe

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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