  Recent attacks using thermal laser stimulation (TLS) have shown that it is
possible to extract cryptographic keys from the battery-backed memory on
state-of-the-art field-programmable gate arrays (FPGAs). However, the
professional failure analysis microscopes usually employed for these attacks
cost in the order of 500k to 1M dollars. In this work, we evaluate the use of a
cheaper commercial laser fault injection station retrofitted with a suitable
amplifier and light source to enable TLS. We demonstrate that TLS attacks are
possible at a hardware cost of around 100k dollars. This constitutes a
reduction of the resources required by the attacker by a factor of at least
five. We showcase two actual attacks: data extraction from the SRAM memory of a
low-power microcontroller and decryption key extraction from a 20-nm technology
FPGA device. The strengths and weaknesses of our low-cost approach are then
discussed in comparison with the conventional failure analysis equipment
approach. In general, this work demonstrates that TLS backside attacks are
available at a much lower cost than previously expected.
