Thursday, May 6, 2021

Backdoor.Win32.Floder.gqe Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/0629e3b2ab8a973a3e37e4e97cb9cfea.txt
Contact: [email protected]
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Floder.gqe
Vulnerability: Insecure Permissions
Description: The malware creates an hidden 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: 0629e3b2ab8a973a3e37e4e97cb9cfea
Vuln ID: MVID-2021-0200
Dropped files: zaberg.exe, Desktop.ini
Disclosure: 05/04/2021

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 /a RECYCLER
Volume in drive C has no label.

Directory of C:\RECYCLER

05/01/2021 11:11 PM <DIR> S-1-5-21-0243556031-888888379-781863308-1830
0 File(s) 0 bytes
3 Dir(s) 7,337,779,200 bytes free

C:\>cd \RECYCLER\S-1-5-21-0243556031-888888379-781863308-1830

C:\RECYCLER\S-1-5-21-0243556031-888888379-781863308-1830>dir /a
Volume in drive C has no label.

Directory of C:\RECYCLER\S-1-5-21-0243556031-888888379-781863308-1830

05/01/2021 11:11 PM 63 Desktop.ini
06/17/2012 02:46 AM 24,064 zaberg.exe
2 File(s) 24,127 bytes


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