TETRA tour de force: Jailbreaking digital radios and base stations for fun and secrets

Presented at DEF CON 31 (2023), Aug. 13, 2023, 2 p.m. (75 minutes)

In this talk we will discuss the radio jailbreaking journey that enabled us to perform the first public disclosure and analysis of the proprietary cryptography used in TETRA (Terrestrial Trunked Radio): a standard used globally by government agencies, police, prisons, and military operators as well as critical infrastructure such as SCADA telecontrol of oil rigs, pipelines, transportation and electric and water utilities. For decades, the underlying algorithms have remained secret under restrictive NDAs prohibiting public scrutiny of this critical technology. In this talk, we will make public the TETRA cipher suites (TEA and TAA1 to be precise), one of the last bastions of widely deployed secret crypto, and discuss in-depth how we managed to obtain them. We will discuss several different flaws we uncovered allowing passive or active adversaries to intercept and manipulate TETRA traffic, including details of a backdoored stream cipher. This journey involved reverse-engineering and exploiting multiple 0-day vulnerabilities in the popular Motorola MTM5x00 radio and its TI OMAP-L138 TEE and covers everything from side-channel attacks on DSPs to writing your own decompilers. We will also discuss how we gained code execution on and instrumented a Motorola MBTS TETRA base station for research purposes. REFERENCES: - Daniel J Bernstein. Cache-timing attacks on AES. 2005. - Shuwen Duan. Security analysis of TETRA. Master’s thesis, Institutt for telematikk, 2013. - Jonas Olofsson. Design and implementation of SIM functionality for TETRA-system on a smart card, 2012. - Yong-Seok Park, Choon-Soo Kim, and Jae-Cheol Ryou. The vulnerability analysis and improvement of the TETRA authentication protocol. 2010 - Martin Pfeiffer, Jan-Pascal Kwiotek, Jiska Classen, Robin Klose,and Matthias Hollick. Analyzing TETRA location privacy and network availability. 2016 - Marek Sebera Tomáš Suchan. TETRA networks security, 2015. - Zhi-Hui Zhang and Yi-Xian Yang. Research on endto-end encryption of TETRA. 2006 - Müller, Uwe ; Hauck, Eicke ; Welz, Timm ; Classen, Jiska ; Hollick, Matthias. Dinosaur Resurrection: PowerPC Binary Patching for Base Station Analysis. 2021


  • Jos Wetzels - Founding Partner and Security Researcher at Midnight Blue
    Jos Wetzels is a co-founding partner and security researcher at Midnight Blue. His research has involved reverse-engineering, vulnerability research and exploit development across various domains ranging from industrial and automotive systems to IoT, networking equipment and deeply embedded SoCs. He has uncovered critical zero-day vulnerabilities in dozens of embedded TCP/IP stacks, Industrial Control Systems (ICS), and RTOSes. He previously worked as a researcher at the Distributed and Embedded Security group (DIES) at the University of Twente (UT) in the Netherlands where he developed exploit mitigation solutions for constrained embedded devices deployed in critical infrastructure, performed security analyses of state-of-the-art network and host-based intrusion detection systems and has been involved in research projects regarding on-the-fly detection and containment of unknown malware and APTs.
  • Wouter Bokslag - Founding Partner and Security Researcher at Midnight Blue
    Wouter Bokslag is a co-founding partner and security researcher at Midnight Blue. He is known for the reverse-engineering and cryptanalysis of several proprietary in-vehicle immobilizer authentication ciphers used by major automotive manufacturers as well as co-developing the world's fastest public attack against the Hitag2 cipher. He holds a Master's Degree in Computer Science & Engineering from Eindhoven University of Technology (TU/e) and designed and assisted teaching hands-on offensive security classes for graduate students at the Dutch Kerckhoffs Institute for several years.
  • Carlo Meijer - Founding Partner and Security Researcher at Midnight Blue
    Carlo Meijer is a co-founding partner and security researcher at Midnight Blue. His research focuses on the analysis of cryptographic systems deployed in the wild. He is known for his work on the security of so-called Self-Encrypting Drives (SEDs). Furthermore, he is known for breaking a hardened variant of Crypto1, the cipher used in the Mifare Classic family of cryptographic RFID tags. Finally, he co-authored research into default passwords in consumer routers as deployed by ISPs in the Netherlands. He is a PhD researcher and systems security lecturer at the Radboud University (RU) in the Netherlands.


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