Abstract

This talk presents a new class of fault injection attacks called bumping attacks. These attacks are aimed at data extraction from secure embedded memory, which usually stores critical parts of algorithms, sensitive data and cryptographic keys. As a security measure, read-back access to the memory is not implemented leaving only authentication and verification options for integrity check. Verification is usually performed on relatively large blocks of data, making a brute force searching infeasible. I will evaluate memory verification and AES authentication schemes used in secure microcontrollers and a highly secure FPGA . By attacking the security in three steps, the search space can be reduced from infeasible 2 to the 100 to affordable 2 to the 15 guesses per block of data. This development was achieved by finding a way to preset certain bits in the data path to a known state using semi-invasive optical bumping. Further improvements to these attacks involved using non-invasive power glitching technique for the secure microcontroller. Partial reverse engineering of the FPGA made bumping attacks possible via the use of non-invasive threshold voltage alteration combined with power glitching. Research into positioning and timing dependency showed that Flash memory bumping attacks are relatively easy to carry out.