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Thread: Cracking VNC Passwords

  1. #1
    Senior Member
    Join Date
    Nov 2001

    Cracking VNC Passwords

    RealVNC is a much used and pretty secure program as far as remote attacks go as long as a strong password is set. But it's only as secure as the computer its on

    Its password is stored locally and is very easily cracked.

    To illustrate this I used a program called x4 which is made spcefically for decoding vnc paswords.

    after i set the password to "my_pass" (so i can put back my real password when im finished) i retrieve it from the registry where it is stored in hexadecimal format


    password b8 1e ac 6a ed f4 36 30

    After starting the program using the -W flag for 'windows interactive' each pair of charecters gets entered one at a time until all eight are entered

    C:\Pwd>x4 -W
    Entered HEX String: b8 1e ac 6a ed f4 36 30
    VNC Password: my_pass


    The decrypted password immeditally appears.

    Do not use vnc on a computer where others that you shouldn't trust have access to it and change the password often. Also keep in mind that the registry is accessable to anyone who gains a remote shell on your computer so keep it patched and firewalled. In earlier version vnc was vulnerable to session hi-jacking and although thats been fixed a weak password can still be brute forced.
    Bukhari:V3B48N826 “The Prophet said, ‘Isn’t the witness of a woman equal to half of that of a man?’ The women said, ‘Yes.’ He said, ‘This is because of the deficiency of a woman’s mind.’”

  2. #2
    Computer Forensics
    Join Date
    Jul 2001
    That's just another reason to tunnel it through ssh

    It doesn't change the fact that it uses weak password algorithms though. Try it on tightvnc if you have the chance.
    Antionline in a nutshell
    \"You\'re putting the fate of the world in the hands of a bunch of idiots I wouldn\'t trust with a potato gun\"

    Trust your Technolust

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