Trojan.Win32.NanoBot.onh / Insecure Permissions

[malvuln <malvuln13 () gmail com>]

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


Disclaimer: The information contained within this advisory is supplied
"as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory,
provided that it is not altered except by reformatting it, and that due
credit is given. Permission is explicitly given for insertion in
vulnerability databases and similar, provided that due credit is given to
the author. The author is not responsible for any misuse of the information
contained herein and accepts no responsibility for any damage caused by the
use or misuse of this information. The author prohibits any malicious use
of security related information or exploits by the author or elsewhere. Do
not attempt to download Malware samples. The author of this website takes
no responsibility for any kind of damages occurring from improper Malware
handling or the downloading of ANY Malware mentioned on this website or
elsewhere. All content Copyright (c) Malvuln.com (TM).

_______________________________________________
Sent through the Full Disclosure mailing list
https://nmap.org/mailman/listinfo/fulldisclosure
Web Archives & RSS: http://seclists.org/fulldisclosure/