Paper Info
Title
A Cautionary Note on Protecting Xilinx’ UltraScale(+) Bitstream Encryption and Authentication Engine
Abstract
FPGA bitstream protection schemes are often the first line of defense for secure hardware designs. In general, breaking the bitstream encryption would enable attackers to subvert the confidentiality and infringe on the IP. Or breaking the authenticity enables manipulating the design, e.g., inserting hardware Trojans. Since FPGAs see widespread use in our interconnected world, such attacks can lead to severe damages, including physical harm. Recently we [1] presented a surprising attack — Starbleed — on Xilinx 7-Series FPGAs, tricking an FPGA into acting as a decryption oracle. For their UltraScale(+) series, Xilinx independently upgraded the security features to AES-GCM, RSA signatures, and a periodic GHASH-based checksum to validate the bitstream during decryption. Hence, UltraScale(+) devices were considered not affected by Starbleed-like attacks [2], [1].We identified novel security weaknesses in Xilinx UltraScale(+) FPGAs if configured outside recommended settings. In particular, we present four attacks in this situation: two attacks on the AES encryption and novel GHASH-based checksum and two authentication downgrade attacks. As a major contribution, we show that the Starbleed attack is still possible within the UltraScale(+) series by developing an attack against the GHASH-based checksum. After describing and analyzing the attacks, we list the subtle configuration changes which can lead to security vulnerabilities and secure configurations not affected by our attacks. As Xilinx only recommends configurations not affected by our attacks, users should be largely secure. However, it is not unlikely that users employ settings outside the recommendations, given the rather large number of configuration options and the fact that Security Misconfiguration is among the leading top 10 OWASP security issues. We note that these security weaknesses shown in this paper had been unknown before.
Year
DOI
Venue
2022
10.1109/FCCM53951.2022.9786118
2022 IEEE 30th Annual International Symposium on Field-Programmable Custom Computing Machines (FCCM)
Keywords
DocType
ISSN
security weaknesses,GHASH-based checksum,authentication downgrade attacks,Starbleed attack,FPGA bitstream protection schemes,secure hardware designs,Xilinx 7-Series FPGAs,UltraScale(+) Bitstream Encryption,Authentication Engine,AES-GCM,RSA signatures,periodic GHASH-based checksum,AES encryption
Conference
2576-2613
ISBN
Citations 
PageRank 
978-1-6654-8333-9
0
0.34
References 
Authors
6
4
Name
Order
Citations
PageRank
Ender, M.132.08
Gregor Leander2128777.03
Amir Moradi396080.66
Christof Paar43794442.62