Security testing of SIP implementations

The Session Initiation Protocol (SIP) is a signaling protocol for Internet telephony, multimedia conferencing and instant messaging. Although SIP implementations have not yet been widely deployed, the product portfolio is expanding rapidly. We describe a method to assess the robustness of SIP implementation by describing a tool to find vulnerabilities. We prepared the test material and carried out tests against a sample set of existing implementations. Results were reported to the vendors and the test suite was made publicly available. Many of the implementations available for evaluation failed to perform in a robust manner under the test. Some failures had information security implications, and should be considered vulnerabilities.