Ncrack is a high-speed network authentication cracking tool. It was designed using a modular approach, a command-line syntax similar to Nmap. It allows for rapid, yet reliable large-scale auditing of multiple hosts. Fixed critical bug in RDP module, which caused Ncracks to fail cracking some Windows 2003 server versions. Added the VNC module to NCrack’s arsenal, allowing you to crack VNC passwords in addition to cracking RDP’s. Added a mechanism (MODULE_ERR), which modules can use to report to the Ncracking engine that the authentication wasn’t completed due to an application error.
Source: https://thehackernews.com/2011/04/ncrack-04-alpha-new-version-download.html