Chairman of the Board CIC - Chairman IoTSI Chile - Advisor to the Board of Directors. - Regional Coordinator CCI - Cyber Researcher - Consejero Comite Ciber - (NED) - Global Ambassadors CyberTalks,
MOAT: Securely Mitigating Rowhammer with Per-Row Activation Counters The security vulnerabilities due to Rowhammer have worsened over the last decade, with existing in-#DRAM solutions, such as TRR, getting broken with simple patterns. In response, the #DDR5 specifications have been extended to support #Per-#Row #Activation #Counting (#PRAC), with counters inlined with each row, and #ALERT-#Back-#Off (#ABO) to stop the memory controller if the DRAM needs more time to mitigate. Although PRAC+ABO represents a strong advance in #Rowhammer #protection, they are just a framework, and the actual security is dependent on the implementation. In this paper, we first show that a prior work, #Panopticon (which formed the basis for PRAC+ABO), is insecure, as our #Jailbreak pattern can cause 1150 activations on an attack row for Panopticon configured for a threshold of 128. We then propose MOAT, a provably secure design, which uses two internal thresholds: #ETH, an Eligibility Threshold for mitigating a row, and ATH, an ALERT Threshold for initiating an ABO. As JEDEC specifications permit a few activations between consecutive ALERTs, we also study how an #attacker can #exploit such activations to inflict more activations than ATH on an attack row and thus increase the tolerated Rowhammer threshold. Our analysis shows that MOAT configured with ATH=64 can safely tolerate a Rowhammer threshold of 99. Finally, we also study performance attacks and #denial of-#service due to ALERTs. Our evaluations, with #SPEC and #GAP workloads, show that MOAT with ATH=64 incurs an average slowdown of 0.28% and 7 bytes of SRAM per bank. Centro de Investigación de Ciberseguridad IoT - IIoT
