Discovery / credits: Malvuln - (c) 2021  
Original source:  
Threat: HEUR.Trojan.Win32.Generic  
Vulnerability: Insecure Permissions  
Description: The specimen creates a dir named "RECYCLER" under c:\ drive and grants change (C) permissions to the authenticated user group. Within the RECYCLER dir exists an hidden dir named with security identifier (SID), which in turn contains a dropped executable named "i7764tg.exe". 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: c60f00700bd73ca369195bd32a3f16a3  
Vuln ID: MVID-2021-0136  
Dropped files: i7764tg.exe  
Disclosure: 03/19/2021  
C:\>cacls \RECYCLER  
C:\RECYCLER BUILTIN\Administrators:(OI)(CI)(ID)F  
NT AUTHORITY\Authenticated Users:(ID)C  
NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C  
C:\RECYCLER>dir /a  
Volume in drive C has no label.  
Directory of C:\RECYCLER  
03/02/2021 11:06 AM <DIR> S-1-5-21-0243556031-888888379-781863308-9761  
0 File(s) 0 bytes  
C:\RECYCLER>cd S-1-5-21-0243556031-888888379-781863308-9761  
C:\RECYCLER\S-1-5-21-0243556031-888888379-781863308-9761>dir /a  
Volume in drive C has no label.  
Directory of C:\RECYCLER\S-1-5-21-0243556031-888888379-781863308-9761  
03/02/2021 11:06 AM 63 Desktop.ini  
06/17/2012 02:29 AM 45,056 i7764tg.exe  
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