HEUR.Trojan.Win32.Generic malware suffers from an insecure permissions vulnerability.
09251124923c21316c7d135fdac3085eDiscovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/c60f00700bd73ca369195bd32a3f16a3.txt
Contact: [email protected]
Media: twitter.com/malvuln
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
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:\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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