Conference:  Defcon 31

Authors: good_pseudonym

2023-08-01

PBX (Private Branch Exchange) and UC (Unified Communications) servers are the big communication brokers in enterprise environments where they love on-prem. They do everything to enable internal and external communications including voice, video, conferencing and messaging. But a broader scope also means a broader attack surface. In this talk, we'll give an overview PBX/UC systems, what kind of attack surface they have, as well as several bugs that we recently found in two popular PBX/UC products. The journey includes deep-diving Java's Runtime.exec(), decrypting encrypted PHP, bypassing license restrictions, pretending to be a phone, and (of course) getting some shells.