Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/9fff4c02274c0162880844f27ff91407.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Trojan.Win32.NanoBot.onh
Vulnerability: Insecure Permissions
Description: NanoBot.onh creates an insecure dir named "AppData" 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. In this case the dropped file "amsiproxy.bat" is actually an PE32 executable as indicated by the presence of MZ header field and binary data.
Type: PE32
MD5: 9fff4c02274c0162880844f27ff91407
Vuln ID: MVID-2021-0173
Dropped files: amsiproxy.bat  (PE32)
Disclosure: 04/17/2021

Exploit/PoC:
C:\>cacls AppData
C:\AppData 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:\AppData\Register-CimProvider>dir
 Volume in drive C has no label.

 Directory of C:\AppData\Register-CimProvider

04/15/2021  10:50 PM         1,101,316 amsiproxy.bat
               1 File(s)      1,101,316 bytes


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