- Business FTTH and fiber optic connections are at risk of interception – and it’s not internet traffic you should worry about.
- DAS technology analyzes the effects of vibration (or sound) on laser pulses via fiber cables
- Attackers can exploit this with the help of AI to decrypt your conversations
New research covered by Science has revealed that the fiber optic cables that connect billions of homes and business premises to the internet could actually be used as covert listening devices.
We’ve already seen submarine cables being repurposed, or multi-purposed, as environmental sensors and data collection tools capable of detecting ships, earthquakes, underwater drones, anchor dredges and much more, but it has now been revealed that fiber optic espionage, previously low risk, is now a higher risk than ever thanks to AI.
According to the analysis, the attack is most feasible on fiber-to-the-home (FTTH) and enterprise connections, where cables run physically close to occupied spaces, where conversations are most likely to take place.
AI now allows cybercriminals to listen to your conversations
The revelation stems from analysis of a technology called Distributed Acoustic Sensing (DAS), which effectively transforms a single fiber optic cable into thousands of vibration sensors distributed along its length.
DAS works by sending laser pulses down a cable and analyzing minor changes in light reflections. These changes are caused by sound waves, which cause tiny deformations in the fiberglass, enough to see measurable differences in the light patterns.
“We show that in almost every case where you use these fibers, there could be a privacy issue,” explained Jack Lee Smith, a geophysicist at the University of Edinburgh, in a presentation at the general assembly of the European Geosciences Union.
The study found that an attacker only needs access to one end of the cable and typically commercially available DAS hardware to carry out an attack, raising widespread security concerns given the proliferation of optical fiber to deliver high-speed broadband and the fact that fiber was previously considered much more secure than copper against interception.
It’s also a reminder that attackers can also exploit less flagged side channels – rather than intercepting internet traffic itself. Remember, they use the physical cable as a vibration sensor to pick up ambient and environmental sounds.
Researchers demonstrated that, under certain conditions and with the help of artificial intelligence, nearby conversations, keyboard typing, television sound and other sounds could be reconstructed.
Real-world limitations, however, threaten its effectiveness as a spying tool. Background noise, signal degradation, cable insulation, and network plugging all decrease an attacker’s chances of converting distorted light signals into reliable audio.
As for non-attackers, this technology is already used in the UK to detect groundwater leaks. It is also used around the world for pipeline monitoring, perimeter security, traffic monitoring and much more, proving that the modest uses of fiber optic cable go far beyond just providing broadband connections.
Smith’s work shows that the actual threat is still low, with the best effectiveness coming from intercepting surface-level coiled cables placed within five meters of a sound. Burying a cable in even just 20 cm of soil is enough to impact sound quality, as are straight cables (even if they are at surface level).
However, while the practical risks remain quite low today, the sheer feasibility of the attack combined with the rapid pace of advances in AI suggests that infrastructure deployed today could pose a greater security risk in the future.
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