The new AGESA patch fixes a critical vulnerability. (Image source: AMD / Google Research)
AMD brings new AGESA firmware (AMD Generic Encapsulated Software Architecture). Version 1.2.0.3c tackles two points – one of them affects a security gap that has really gained driving in the past few weeks. We are talking about the weak point mentioned “Ensign”, which is led under the identification CVE-2024-36347 and closed with the new update.
- Originally, security researchers assumed that “only” processors up to Zen 4 (via Tom’s Hardware) are affected.
- Recently, however, AMD had to determinethat all current Zen-5 CPUs can be caught by Entrysign. Both Ryzen 9000 and Ryzen 9000x3D and the EPYC 9005 series were one of the potential attack vectors.
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Entrysign: A jailbreak for the AMD CPU
Entrysign itself enables attackers to avoid the verification of microcode updates. This verification usually runs over a cryptographic signature-more precisely aes-cmac, like that Google researcher explain that the weak point only discovered.
However, AES-CMAC is more designed for news authentication and not for cryptographic hash function, so that Google researchers managed to engage in their own microcode.
Tavis Ormandy, who was involved in the EntrySign examinations, said succinctly: “You can now make your AMD CPU Jailbreak”. A associated Github repository was uploaded for this.
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After all, there are two consolation plasters. In order for entrysign to work, attackers need access to system ring 0, i.e. the most privileged level of the kernel. In addition, the manipulated microcode does not remain after a restart of the system.
Support for 192 GB DDR5-6000
Agesa version 1.2.0.3c brings support for faster memory, as from the first BIOS updates from mainboard manufacturers (via Uniko's hardware) that is based on the AMD firmware.
MSI, for example, now leads the first bar assemblies with a whopping 192 GB of GDR5 RAM – at a speed of 6,000 MT/s. These consist of four RAM sticks, each with 48 GB. However, it should not stay if it goes to the manufacturers of RAM, because G.Skill has introduced the first kits with 256 GB of DDR5-6000 with CL32.
