Hacker Interviews – Karsten Nohl

Pierluigi Paganini July 04, 2016

Karsten NohlFor the cyber security experts, Karsten Nohl doesn’t need to be introduced, he is volcanic, a shining professional. Karsten Nohl is one of the most famous hackers in the world, laymen know him as the hacker that revealed to the world how to spy on anyone through the vulnerability in the SS7 protocol.

Karsten Nohl has spoken widely on security gaps since 2006, he and co-investigators have uncovered flaws in mobile communication, payment, and other widely-used infrastructures. In his work as CISO at an Asian 4G and digital service provider, and as Chief Scientist at Security Research Labs in Berlin, a risk management think tank specializing in emerging IT threats, Karsten challenges security assumptions in proprietary systems and is fascinated by the security-innovation trade-off. Hailing from the Rhineland, he studied electrical engineering in Heidelberg and earned a doctorate in 2008 from the University of Virginia.


Enjoy the interview!

I consider you a professional belonging to the hacker elite, I remember your studies on the SS7 security issues, on the European credit card payment terminals and about the vulnerability in encryption technology used for SIM cards. No doubts, you are polyhedric and ingenious, but please tell me more about you, which his your technical background and when you started hacking?

Let me first say that what my team and I are doing is nothing extraordinary. Any collection of IT and hardware professionals given the right amount of time and funding can find the flaws that we discover. We may just be a bit more persistent, often working for several years on a topic before presenting our results.

My background is Electrical Engineering with a PhD in Computer Engineering. Both degrees taught me how hardware and software interact, based on which I can today interfere where insecurities may emerge between these layers. I also have a great fascination for cryptography, which helps in debunking insecure crypto implementations often found in embedded systems.

What was your greatest hacking challenge?

It’s hard to compare research projects. In retrospect, anything is easy and 90+% of the project time is spent going down the wrong paths. Most technologically challenging was probably our work with SIM cards, which involved breaking into smartcards, reverse engineering embedded operating systems, reimplementing complex mobile protocols, and running worldwide scans without anybody noticing.

What are the 4 tools that cannot be missed in the hacker’s arsenal and why?

Good hackers rarely rely on tools. Having said that, IDApro saves enormous time, especially with its relatively new decompiling feature. The AFL fuzzer and Zmap are great implementations of rather simple ideas that come in handy when testing software or large networks, respectively. Lastly, I wouldn’t want to miss SSLstrip, which requires continuous maintenance to stay useful, though.

Which are the most interesting hacking communities on the web today?

Given the luxury of having some of the best hacking discussion within my own team in Berlin, I don’t actually know where people exchange ideas online 🙂

Which is the industry (healthcare, automotive, telecommunication, banking, and so on) most exposed to cyber attacks and why? What scares you more in the internet?

Every industry that uses computers is exposed to attacks. This is: Every industry. Not all industries are equally interesting to hackers, though. We still learn about the most advanced hacking techniques from banks first, often 6 months before anybody else sees these new hacking trends.

Let’s speak about your research about SS7 security issues and surveillance abilities through the exploitation of a so dated protocol You demonstrated that using the protocol is possible to intercept data and geo-track every mobile in the world. Based on your experience Is it an intelligence prerogative or do you believe that also criminal rings are exploiting the SS7 protocol for illegal activities? How much cost the equipment to carry on such kind of surveillance? What do you need to do it?

The SS7 protocol is actively being exploited by state agencies and private organizations. The protocol flaws allow world-wide intercept and tracking of mobile phone users. Attacks are relatively easy to implement and SS7 access is available commercially. Companies such as Ability and Circles actively market their SS7-based spying capabilities.

Mobile networks finally started moving, too, with SS7 firewalls being implemented in numerous networks. Here’s to hoping that the current momentum will actually lead to better privacy for mobile customers, something most telcos have ignored for far too long.telcos have ignored for far too long.

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Pierluigi Paganini

(Security Affairs –  Hacker, Karsten Nohl)

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