VoIP (Voice over Internet Protocol) technology is developing rapidly, and Skype is the most popular VoIP product on the market. Skype allows users to reduce telephone charges significantly compared to traditional telephone networks, with no loss of connection quality. A second advantage is ease of use. Users worldwide are up and running in seconds: Simply install Skype and plug in a microphone. That done, one can talk, exchange files, text messages and so on. However, Skype take-up has gone beyond domestic users — it is also used on corporate networks. This is not surprising when one considers how it significantly reduces the cost of long-distance and international calls and simplifies inter-office and person-to-person communications. On top of that, the utility requires no administrator privileges to set up and use. Employees can download Skype from the Internet for free and simply install it on their corporate workstations. This gives rise to a new problem: The increased Information Security (IS) risk of Skype use in the corporate environment. The issue of Skype and network security is pressing. It is a widespread program which attracts the attention of both insiders and hackers alike.