Security Status of VoIP Based on the Observation of Real-World Attacks on a Honeynet

VoIP (Voice over IP) systems are more and more replacing PSTN (Public Switched Telephone Network) infrastructures. This increases the dependency on available and secure VoIP systems for successful business. Attacks against VoIP systems are becoming more imaginative and many attacks can cause damage, e.g., gain money for attackers or create costs for the victim. Therefore, in this paper the current security status of VoIP systems is described by analyzing real-world attacks collected in a honey net solution. In order to get the results, a classification, an analysis and a validation of the collected data were performed. The achieved results deliver information about Identity Theft, Malformed Messages, Fraudulent Calls as well as Attacker Behaviors and can help to adapt existing prevention systems to avoid the recognized and analyzed attacks in a productive environment.