AMD Zen 2 platform has reportedly been vulnerable to a new "Zenbleed" bug, contributing to large-scale data theft and several potential attacks.
AMD Zen 2 CPUs Are Now Prone to Data Leaks; Most Fixes Will Release By End of 2023
Tavis Ormandy, a researcher at Google Information Security, initially discovered the vulnerability. The bug expands to all processors within the Zen 2 architecture, such as Ryzen 3000/4000/5000 and AMD EPYC CPUs. The "Zenbleed" bug doesn't require a physical platform and can be executed through web pages and online data. However, one positive aspect is that AMD has acknowledged the vulnerability by releasing a "Security Bulletin," highlighting the issue in detail.
Expanding on the "Zenbleed" bug, it facilitates illegal data extraction at 30kb per core per second. Since this attack is mainly software-based, it can steal information through all software elements running on the processor, such as virtual machines. The bug can be executed through an unprivileged arbitrary code execution by changing the register files. Here is how the security expert details the bug:
The bug works like this, first of all you need to trigger something called the XMM Register Merge Optimization2, followed by a register rename and a mispredicted vzeroupper. This all has to happen within a precise window to work.
We now know that basic operations like strlen, memcpy and strcmp will use the vector registers - so we can effectively spy on those operations happening anywhere on the system! It doesn’t matter if they’re happening in other virtual machines, sandboxes, containers, processes, whatever!
This works because the register file is shared by everything on the same physical core. In fact, two hyperthreads even share the same physical register file.
The "Zenbleed" bug is said to impact the performance of the Zen 2 CPUs, although the extent of the downgrade isn't specified yet. As of writing, this bug could potentially be present in several CPUs; hence a permanent fix should be a priority for the company right now; however, there are complications. AMD's scheduled release date for AESGA firmware for several OEMs is not anticipated unit Oct 2023. Here is a table compiled by Tom's Hardware to give you a brief idea about the expected updates:
| Processor | Agesa Firmware | Availability to OEMs | Microcode |
| 2nd-Gen AMD EPYC Rome Processors | RomePI 1.0.0.H | Now | 0x0830107A |
| Ryzen 3000 Series “Matisse” | ComboAM4v2PI_1.2.0.C | ComboAM4PI_1.0.0.C | Target Dec 2023 for both | ? |
| Ryzen 4000 Series "Renoir" AM4 | ComboAM4v2PI_1.2.0.C | Target Dec 2023 | ? |
| Threadripper 3000-Series "Caslle Peak" | CastlePeakPI-SP3r3 1.0.0.A | Target Oct 2023 | ? |
| Threadripper PRO 3000WX-Series "Castle Peak" | CastlePeakWSPI-sWRX8 1.0.0.C | ChagallWSPI-sWRX8 1.0.0.7 | Target Nov 2023 | Target Dec 2023 | ? |
| Ryzen 5000 Series Mobile "Lucienne" | CezannePI-FP6_1.0.1.0 | Target Dec 2023 | ? |
| Ryzen 4000 Series Mobile "Renoir" | RenoirPI-FP6_1.0.0.D | Target Nov 2023 | ? |
| Ryzen 7020 Series "Mendocino" | MendocinoPI-FT6_1.0.0.6 | Target Dec 2023 | ? |
However, Tavis has also suggested an interim fix through software tuning, This would result in a higher performance tradeoff, and the method involved is complex for an average consumer. Tavis reportedly informed AMD about the problem on May 15, 2023, but the company didn't resolve it quickly. We now suggest consumers on the Zen 2 platform wait for the upcoming AGESA codes. We will surely update our readers with any further developments on the topic.
from Wccftech https://ift.tt/wzkrRy2
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