Key Takeaways
1. Spectre and Meltdown flaws in x86 processors led to major issues for Intel and AMD in 2018, resulting in lawsuits and the need for microcode updates.
2. New vulnerabilities related to Spectre were discovered in Intel CPUs, particularly the Alder Lake series, and ARM cores, impacting performance variably.
3. ETH Zurich’s research revealed that existing mitigations could still be bypassed under certain conditions.
4. Intel’s January 2025 microcode update showed minimal performance overhead in most chips, but Rocket Lake experienced an 8.3% performance decrease.
5. The vulnerabilities affect all operating systems, but AMD and ARM chips are not impacted by the newly identified flaws.
The Spectre and Meltdown flaws that impacted X86 processors created major issues for Intel and AMD in 2018, leading to lawsuits against both firms. ARM also faced these vulnerabilities, but all companies ultimately issued in-silicon microcode updates to address the bugs. While these updates resulted in some performance loss, it wasn’t severe. In 2022, more Spectre risks were identified for Intel CPUs, including the Alder Lake series, and for ARM cores, with the degree of performance loss varying based on the specific task. Unfortunately, this was not the end of Spectre troubles for Intel, as a new report from ETH Zurich has uncovered additional vulnerabilities for Intel CPUs from 2018 to 2024, some of which show notable performance drops after applying updated mitigations.
Testing New Mitigations
ETH Zurich performed detailed examinations of the previously released mitigations, such as the enhanced Indirect Branch Restricted Speculation (eIBRS) and the Indirect Branch Prediction Barrier (IBPB). Their findings suggest that, under certain conditions, these mitigations can still be circumvented.
Intel’s Response
In January 2025, Intel rolled out a new microcode with better mitigations, enabling ETH Zurich to assess its impact on newer CPU models. The results indicated that most chips experienced minimal effects, with Alder Lake processors showing only a 2.7% performance overhead, Raptor Lake and Raptor Lake-R having less than 2%, and Coffee Lake-R at 1.6%. However, Rocket Lake was an outlier, showing an 8.3% decrease in performance.
Broader Implications
Although ETH Zurich’s evaluations were conducted solely on Linux systems, it’s established that these vulnerabilities can affect any operating system. AMD and ARM chips, however, are not impacted by these newly identified flaws.
Intel has reportedly delivered the new microcodes to all system builders and operating system developers. In a blog post dated May 13, the company stated, “Intel is enhancing its Spectre v2 hardware mitigations and recommends that customers check INTEL-SA-01247 and reach out to their system manufacturers for the correct updates. So far, Intel is unaware of any real-world exploits related to transient execution vulnerabilities.”
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