Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/373b1d95ccdbbc6531dff43bbbe43534.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Trojan-Downloader.Win32.Delf.oxz
Vulnerability: Insecure Permissions
Description: Win32.Delf.oxz creates an 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: 373b1d95ccdbbc6531dff43bbbe43534
Vuln ID: MVID-2021-0156
Dropped files: winrao.exe
Disclosure: 04/01/2021

Exploit/PoC:
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


C:\>dir RECYCLER\
 Volume in drive C has no label.

 Directory of C:\RECYCLER

               0 File(s)              0 bytes

C:\>attrib -s -h \RECYCLER\*

C:\>dir RECYCLER\
 Volume in drive C has no label.

 Directory of C:\RECYCLER

12/30/2019  02:34 AM           242,176 winrao.exe
               1 File(s)        242,176 bytes


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