Μηχανισμός εντοπισμού κακοσχηματισμένων SIP μηνυμάτων

Αυγού, Ελένη Ε.

Master Thesis

Author

Αυγού, Ελένη Ε.

Date

2015-03-06

Abstract

This postgraduate study focuses on the weaknesses of the SIP protocol is used for communication in IMS (IP Multimedia Subsystem) and VOIP, and threats can messages arise from malicious users. Specifically, we study the threat resulting from malformed SIP messages and present an implementation of a mechanism that is able to read these messages, find anomalies, and to decide whether they can cause damage to the parser that will read and forward them to the appropriate destination. Utilizing this model and integrating it into an IMS system can result in avoiding failures or even system crash caused by malformed as it could block the transfer. More specifically, in the first chapters we refer to the IP Multimedia Subsystem as well as Voice Over IP to mention the widely spread and the need for security of communication via SIP protocol use. Then, we analyze the SIP protocol, the elements of which it is composed and how it contributes to the exchange of messages between users. Extensive analysis of messages exchanged the structure that they should follow, depending on the category to which they belong, will be presented. Finally, we present the threats to which the SIP protocol is exposed due to its weaknesses and how these have led to serious attacks. The mechanism which is presented is exploiting the messages of Protos Test Suite to verify its validity in detecting malformed messages. 3 test cases of messages that could cause problem to the parser and how they are detected by this mechanism are shown in the end.