Get the Whitepaper called Skype Voice Over IP Software Vulnerabilities, Techniques and Methods – Zero Day Exploitation 2011.
You can download it from the following link: https://packetstormsecurity.com/files/download/106030/skype-vulns.pdf
Source: https://packetstormsecurity.com/files/106030/Skype-VoIP-Zero-Day-Exploitation.html