Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/1d6d6d3c077250b7b3ad053e71054ecc.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Trojan-Dropper.Win32.Dycler.vrp
Vulnerability: Insecure Permissions
Description: The malware creates an insecure dir named "Drivers" 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: 1d6d6d3c077250b7b3ad053e71054ecc
Vuln ID: MVID-2021-0186
Dropped files: dlhost.exe, hgo.bat
Disclosure: 04/27/2021


Exploit/PoC:
C:\>cacls Drivers
C:\Drivers 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:\Drivers>attrib -s -h symbols

C:\Drivers>dir symbols
 Volume in drive C has no label.F

 Directory of C:\Drivers\symbols

10/13/2011  09:50 AM         1,710,592 dlhost.exe
10/13/2011  09:52 AM                79 hgo.bat
04/26/2021  08:36 PM    <DIR>       Microsoft.VC90.CRT
               2 File(s)      1,710,671 bytes
               3 Dir(s)   6,918,037,504 bytes free



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