CVE-2018-3639

Los sistemas con microprocesadores que emplean la ejecución especulativa y que realizan la ejecución especulativa de lecturas de memoria antes de que se conozcan las direcciones de todas las anteriores escrituras de memoria podrían permitir la divulgación no autorizada de información a un atacante con acceso de usuario local mediante un análisis de canal lateral. Esto también se conoce como Speculative Store Bypass (SSB), Variant 4.

An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of Load & Store instructions (a commonly used performance optimization). It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory read from address to which a recent memory write has occurred may see an older value and subsequently cause an update into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to read privileged memory by conducting targeted cache side-channel attacks.

Variant 4 of the speculative execution vulnerability that focuses on a speculative store bypass.