An Armful of CHERIs – Microsoft Security Response Center
Today, Arm announced that the first silicon supporting the Morello prototype architecture, a research project led by Arm, Microsoft, University of Cambridge and others, is now available on a limited run of demonstration boards, which are being shipped from today to industry partners for testing. Morello is the first high-performance implementation of the CHERI extensions. CHERI provides fine-grained spatial memory safety at a hardware level. We’ve previously completed a security review of a prototype of the CHERI software stack on QEMU and will now have the opportunity to more deeply evaluate CHERI on a fast contemporary superscalar processor.
The Portmeirion Project is a collaboration between Microsoft Research’s Confidential Computing Group and the Microsoft Security Response Center that is exploring hardware-software co-design for security and will be working with these systems.
Unlike many other proposed memory-safety technologies, CHERI (by design) does not depend on secrets. This means that it deterministically mitigates vulnerability classes, rather than giving a high probability of detecting them. Probabilistic mitigations have not historically shown to be durable because attackers find ways of leaking the secrets and turning low-probability attacks into high-probability attacks. An attacker can bypass any mitigation that depends on secrets by leaking the secret and may be able to bypass it with a high probability if they can reduce the entropy of the secret. The deterministic aspect of CHERI also means that it can be used as a building block for higher-level security abstractions.