Tobias Engel
More info
- Known for
- SS7 attacks on mobile networks
- Venue
- Chaos Communication Congress (2008, 2014)
German security researcher who showed that the mobile network's internal signalling lets anyone with access locate, and listen to, a phone.
SS7 is the 1970s signalling system carriers use to set up calls and handle roaming. It was designed for a closed club of state telephone monopolies, so every node trusts every other node. At 25C3 in 2008, Engel showed that SS7 access was enough to look up a subscriber's rough location from nothing but a phone number.
At 31C3 in 2014 he went further: tracking, call redirection and interception. Karsten Nohl presented similar findings at the same congress. The problem wasn't a bug but an architecture, and SS7 access could be rented from less scrupulous operators. Hence the now-standard advice that SMS codes make a weak second factor.