New Spectre (Variant 4) CPU Flaw Discovered—Intel, ARM, AMD Affected

Variants 1 and 2 (CVE-2017-5753 and CVE-2017-5715), known as Spectre, and Variant 3 (CVE-2017-5754), known as Meltdown, are three processor vulnerabilities disclosed by Google Project Zero researchers in January this year.

Speculative execution is a core component of modern processors design that speculatively executes instructions based on assumptions that are considered likely to be true. If the assumptions come out to be valid, the execution continues and is discarded if not.

However, the speculative-execution design blunders can be exploited by malicious software or apps running on a vulnerable computer, or a nefarious actor logged into the system, to trick the CPU into revealing sensitive information, like passwords and encryption keys, stored in system memory and the kernel.

Unlike Meltdown that primarily impacted Intel chips, Spectre affects chips from other manufacturers as well.


Spectre and Meltdown Continues to Haunt Intel, AMD, ARM

Speculative Store Bypass attack is so far demonstrated in a “language-based runtime environment.” The most common use of runtimes, like JavaScript, is in web browsers, but Intel had not seen any evidence of successful browser-based exploits.

Linux distro giant Red Hat has also provided a video outlining the new Spectre flaw, alongside publishing a substantial guide:

“Starting in January, most leading browser providers deployed mitigations for Variant 1 in their managed runtimes—mitigations that substantially increase the difficulty of exploiting side channels in a web browser,” Intel says in its advisory. “These mitigations are also applicable to Variant 4 and available for consumers to use today.”

Spectre Mitigations to Result in Another Performance Hit

ARM and AMD are also releasing security patches for their respective chips, with ARM saying the latest Spectre variant impacts only a small number of Arm Cortex-A cores and is mitigated with an Arm-developed firmware update.

AMD also released a whitepaper, advising users to leave the fix disabled due to the inherent difficulty of performing a successful Speculative Store Bypass attack and saying:

“Microsoft is completing final testing and validation of AMD-specific updates for Windows client and server operating systems, which are expected to be released through their standard update process.”

“Similarly, Linux distributors are developing operating system updates for SSB. AMD recommends checking with your OS provider for specific guidance on schedules.”

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