It'S Hammer Time: How To Attack (Rowhammer-Based) Dram-Pufs

Physically Unclonable Functions (PUFs) are still considered promising technology as building blocks in cryptographic protocols. While most PUFs require dedicated circuitry, recent research leverages DRAM hardware for PUFs due to its intrinsic properties and wide deployment. Recently, a new memory-based PUF was proposed that utilizes the infamous Rowhammer effect in DRAM. In this paper, we show two remote attacks on DRAM-based PUFs. First, a DoS attack that exploits the Rowhammer effect to manipulate PUF responses. Second, a modeling attack that predicts PUF responses by observing few challenge-response pairs. Our results indicate that DRAM may not be suitable for PUFs.