VNC challenge response password crack

[AJB]

Wow very cool, according to https://en.wikipedia.org/wiki/Virtual_Network_Computing there are different protocols used by different VNC clients. Which protocol/clients use this particular method of authentication?

The protocol it uses is RFB ("Remote FrameBuffer"). Even though it is not the most secure protocol, it is important to note that often VNC is used with another security layer. For example, RealVNC uses TLS which makes it harder for someone who is sniffing the traffic to retrieve the challenge-response and so, to crack the password. Also, as it is written on Wikipedia, VPN or SSH connection could be used to add security.