- AMD Advisory warns of a new high severity security defect
- The bug affects Zen 1 to Zen 4 CPUS
- Abuse could lead to the loss of sev protection of a confidential guest
The AMD sieve manufacturing giant confirmed that it had recently corrected a high severity vulnerability affecting its Zen 1 processors to Zen 4.
The company has published a new security advice, detailing the bug and its operating potential, noting: “Google researchers provided AMD information on a potential vulnerability which, if it is successfully exploited, could lead to The loss of protection based on SEV of a confidential guest. “”
SEV is short for secure encrypted virtualization – a safety function based on equipment designed to improve the confidentiality and integrity of virtual machines (VMS) operating on AMD EPYC processors. He encrypts the memory of individual virtual machines using unique encryption keys, ensuring that neither the hypervisor nor other VMs can access their data.
Available attenuations
Vulnerability is followed as CVE-2024-56161 and has a gravity score of 7.2 / 10 (high). It is described as an inappropriate signature verification defect in the Patch of Patch of Microcode Rom CPU AMD, which could allow threat actors with local administration privileges to charge the malicious processor microcode. Consequently, the confidentiality and integrity of a confidential guest operating under AMD SEV-SNP would be lost.
“AMD has made an attenuation of this problem attenuation which requires an update of the microcode on all the affected platforms to help prevent an attacker from loading a malicious microcode,” concluded the company.
“In addition, an update of the SEV firmware is required for certain platforms in order to support the SEV-SNP certificate. Updating the image of the system bios and restarting the platform will achieve attenuation. A confidential guest can verify that attenuation has been activated on the target platform via the SEV-SNP certificate report. »»
The company only publicly revealed the fault recently, but the patch was published in mid-December 2024. AMD decided to delay the announcement to give its customers enough time to mitigate the problem.
