Backdoor.Win32.RemoteManipulator.fdo / Insecure Permissions

[malvuln <malvuln13 () gmail com>]

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


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