Attacking VNC Servers

30 Oct

Often in infrastructure penetration tests,you might come across with the VNC service.The main use of this service is because systems administrators want to control remotely other systems or for technical support issues.So when a penetration tester discovers a VNC server running on port 5900 then it is a good practice to check if he could gain access to the system from that service by testing it for weak passwords.In this tutorial we will see how we can attack a VNC server.

So lets say that we have discover a VNC service running on port 5900 through our nmap scan.

VNC Service Discovery


Now we can use the metasploit framework in order to attack this service.The module that we will need is the vnc_login.Unfortunately metasploit doesn’t provide a big word-list for this module so we might want to use an alternative word-list in order our attack to have more efficiency.We are configuring the module and we are executing it with the run command.

VNC Authentication Scanner


As we can see from the image above the vnc scanner has managed to authenticate with the password admin.Now we can use the VNC viewer in order to authenticate with the remote host and to start the post exploitation activities.


VNC is a service that it can be discovered quite often in networks.As we saw the metasploit module is simple and effective and it can be used for testing this service.Metasploit provides of course and other modules that can exploit VNC vulnerabilities but in order to use these modules it is advisable first to be in contact with your client.


Posted by on October 30, 2012 in Exploitation Techniques


Tags: , , ,

3 responses to “Attacking VNC Servers

  1. Mr Meow

    October 30, 2012 at 12:56 pm

    Thanks for another sexy post❤

  2. sbrinn

    November 23, 2012 at 4:09 pm

    Your english is really bad, but I like the post🙂

  3. netbiosX

    November 24, 2012 at 10:33 am


    I have corrected the errors.Well these things can happen when English is not your mother language and you don’t have the time to double check the posts!Thank you for the feedback.


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