Ransomware Builder Babuk Insecure Permissions Vulnerability

Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source: https://malvuln.com/advisory/5dfa998f62612e10d5d28d26948dd50f.txt
Contact: [email protected]
Media: twitter.com/malvuln

Threat: Ransomware Builder Babuk
Vulnerability: Insecure Permissions
Description: The malware creates directorys with insecure permissions when write to c:\ drive, granting change (C) permissions to the authenticated user group. 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: 5dfa998f62612e10d5d28d26948dd50f
Vuln ID: MVID-2022-0461
Disclosure: 01/19/2022


Exploit/PoC:
C:\>builder.exe
Usage: builder.exe FolderName

C:\>builder.exe c:\hate
Creating folder 'c:\hate'
curve25519 keys generated.
"c:\hate\e_win.exe" written!
"c:\hate\d_win.exe" written!
"c:\hate\e_esxi.out" written!
"c:\hate\d_esxi.out" written!
"c:\hate\e_nas_x86.out" written!
"c:\hate\d_nas_x86.out" written!
"c:\hate\e_nas_arm.out" written!
"c:\hate\d_nas_arm.out" written!
"c:\hate\kp.curve25519" written!
"c:\hate\ks.curve25519" written!
Press any key to continue . . .

C:\>cacls \hate
C:\hate 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


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