Keep Your AMD CPUs Updated

It’s crucial for owners of AMD CPUs ranging from Zen 1 to Zen 4 architectures to verify that their BIOS is current. A report from Tom’s Hardware indicates that AMD processors with BIOS updates before 2014-12-17 may possess a vulnerability. This flaw enables those with local admin access to upload new microcode to the CPUs, potentially compromising system integrity.

Recent Exploits

The security breach was uncovered by Google researchers collaborating with AMD, affecting a wealth of processors released in the past eight years. For instance, older models like the Ryzen 7 5700X3D could be at risk if they aren’t updated, while newer models such as the Ryzen 7 9800X3D are not vulnerable due to recent architectural enhancements.

With the recent patch fixing the exploit, the research team has documented their findings and methods, including how to perform a DIY hack on the microcode. If you’re considering jailbreaking your CPU, you might want to delay those updates for now.

Security Implications

EntrySign is reported to be easily exploited due to inadequate cryptographic practices, specifically by using the AES-CMAC function instead of a robust cryptographic hash function. This issue makes it straightforward for individuals with access to the encryption key to reverse-engineer operations.

The implications for security are serious. Access to altering microcode can lead to significant issues, especially for virtual machines, where the topmost security layer allows direct communication with hardware. Fortunately, the changes are not maintained after a reboot; thus, rebooting any impacted devices and promptly updating the BIOS should resolve the vulnerabilities.

Keeping your CPU updated is the most effective defense against these security risks. Avoid the potential pitfalls of outdated BIOS versions.