Wednesday, February 17, 2021

Backdoor.Win32.Bifrose.ahvb Insecure Permissions

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/39e22b8b19f6aed59d2def00c4228d56.txt
Contact: [email protected]
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Bifrose.ahvb
Vulnerability: Insecure Permissions
Description: The backdoor creates an insecure dir named "Temp" under c:\ drive, granting change (C) permissions to the authenticated user group.
Type: PE32
MD5: 39e22b8b19f6aed59d2def00c4228d56
Vuln ID: MVID-2021-0090
Dropped files: iwbfh482008c.exe
Disclosure: 02/15/2021

Exploit/PoC:
C:\>cacls \Temp
C:\Temp 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 \Temp
Volume in drive C has no label.

Directory of C:\Temp

02/14/2021 10:01 PM <DIR> .
02/14/2021 10:01 PM <DIR> ..
02/14/2021 10:01 PM 689,664 iwbfh482008c.exe
1 File(s) 689,664 bytes


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