TEMPEST attacks are often the most effective way to break air-gapped security: rather than directly accessing a computer, the attacker records the system’s unintended radio emissions and uses them to reconstruct its internal operations. This kind of attack was much more effective in the days of noisy, high-voltage CRT displays, and has gradually become less effective as electronics migrate to quieter, less powerful components. A group of researchers, however, has found that even modern electronics can become effective TEMPEST transmitters when irradiated with an RF signal.
The RF a device emits depends on the unintentional antennas in its internal structure. These are difficult to eliminate, and it’s usually not worth the effort; they’re usually small enough that they only effectively radiate at much higher frequencies than the electronics carry. The researchers’ technique, called InjectEave, radiated these electronics with a radio frequency tuned to their internal antennas, injecting that frequency into the circuit. Nonlinear electronic components, such as amplifiers, then mix the injected frequency with the internal signal, creating RF sidebands. This mixed signal then radiates out of the device and can be picked up and demodulated to recover the device’s internal signal.
Continue reading “Reviving TEMPEST Attacks With An Injected Signal”
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