Backdoor.Win32.Bifrose.ahyg / Insecure Permissions

[malvuln <malvuln13 () gmail com>]

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/d6aff119c03ff378d386b30b36b07a69.txt
Contact: malvuln13 () gmail com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Bifrose.ahyg
Vulnerability: Insecure Permissions
Description: The malware creates an dir with insecure permissions
under 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.
Type: PE32
MD5: d6aff119c03ff378d386b30b36b07a69
Vuln ID: MVID-2021-0356
Dropped files: vfenr522008a.exe
Disclosure: 10/04/2021

Exploit/PoC:
C:\>cacls Temp
C:\Temp 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:\>dir Temp
 Volume in drive C has no label.

 Directory of C:\Temp

10/03/2021  01:40 AM           689,664 vfenr522008a.exe
               1 File(s)        689,664 bytes


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