AMD ‘Zenbleed’ exploit can leak passwords and encryption keys from Zen 2 CPUs

Tavis Ormandy uncovered a flaw "Zenbleed" (CVE-2023-20593) in Zen 2 by exploiting precise scheduling and vzeroupper to spy on operations like strlen, memcpy and strcmp. This vulnerability is capable of spying on operations across virtual machines, sandboxes, containers, and processes, could leak up to 30 kb/core/sec of sensitive data!

According to Cloudflare, the Zenbleed exploit doesn’t require physical access to a user’s computer to attack their system, and can even be executed remotely through Javanoscript on a webpage. The flexibility of this exploit is a particular concern for cloud-hosted services as it could potentially be used to spy on users within cloud instances.

The entire Zen 2 product stack is impacted by the vulnerability, including all processors within the AMD Ryzen 3000 / 4000 / 5000 / 7020 series, the Ryzen Pro 3000 / 4000 series, and AMD’s EPYC “Rome” data center processors. AMD has already released a microcode patch for second-generation Epyc 7002 processors, though the next updates for the remaining CPU lines aren’t expected until October 2023 at the earliest.

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