Hi all, I am Youngsung Kim (Facebook, Twitter) of the Application Security team at LINE and am in charge of evaluating security of LINE services. On this post, I’d like to share a vulnerability (CVE-2017-16872, AST-2017-009) of PJSIP, a VoIP open source library. PJSIP is a multimedia communication library based on the following standard protocols; SIP, SDP, RTP, STUN, TURN, and ICE. The Asterisk framework, widely used on IP-PBX and VoPI gateway has an SIP stack implemented based on PJSIP.
The cause of the vulnerability was due to incautiousness about sign extension for Integers in the process of converting
signed int to
unsigned long when handling client’s SIP requests on 64-bit environment. There was no window to report the security issue to the PJSIP development teams, so I made my report to the Asterisk’s security page. Afterwards, I’ve consulted with George Joseph, an engineer at Asterisk, and the patch (PJSIP patch, Asterisk patch) has been applied on the pjproject v2.7.1. I’d like to express my gratitude to George for processing the patch.