Hunting For Vulnerabilities in Signal

March 22, 2017 (at 2:30 p.m.) in Attack and Research

Signal is the most trusted secure messaging and secure voice application, recommended by Edward Snowden and the Grugq. And indeed Signal uses strong cryptography, relies on a solid system architecture, and you've never heard of any vulnerability in its code base. That's what this talk is about: hunting vulnerabilities in Signal.

We will present vulnerabilities found in the Signal Android client, in the underlying Java libsignal library, and in example usage of the C libsignal library. Our demos will show how these can be used to crash Signal remotely, to bypass the MAC authentication for certain attached files, and to trigger memory corruption bugs.

Combined with vulnerabilities in the Android system it is even possible to remotely brick certain Android devices. We will demonstrate how to initiate a permanent boot loop via a single Signal message.We will also describe the general architecture of Signal, its attack surface, the tools you can use to analyze it, and the general threat model for secure mobile communication apps. Open Whisper Systems, which maintain Signal, rapidly acknowledged and fixed the vulnerabilities.

Jean-Philippe Aumasson

Jean-Philippe (JP) Aumasson is Principal Research Engineer at Kudelski Security, in Switzerland. He designed the popular cryptographic functions BLAKE2 and SipHash, and the new authenticated cipher NORX. He has spoken at Black Hat, DEFCON, RSA, CCC, SyScan, Troopers. He initiated the Crypto Coding Standard and the Password Hashing Competition projects, co-wrote the 2015 book "The Hash Function BLAKE", and will release a new cryptography book in 2017 for a wider audience. JP tweets as @veorq.

Markus Vervier

Markus Vervier is a security researcher from Germany. Software security is his main focus of work. During the last 15 years he collected professional experience in offensive IT security working as a penetration tester and security consultant for highly regarded companies. His experience combined with his personal passion regarding security research made him start his own company in 2015. Besides his daily security work, he is very actively practicing security research and discovers high profile vulnerabilities regularly such as the recent libotr heap overwrite.