Google and Microsoft Disclose New Security Flaw ‘Speculative Store Bypass (Variant 4)’

Meltdown and Spectre Apple

On May 21, both Google and Microsoft are jointly disclosing a new CPU hardware security flaw that is similar to Spectre and Meltdown.

The new security flaw is known as “Speculative Store Bypass (variant 4)”, which exploits speculative execution that modern CPUs utilize. It is worth noting, though, that browsers like Apple’s Safari, Microsoft’s Edge, and Google’s Chrome were pathed for Meltdown earlier this year, and, as a result, Intel says, “these mitigations are also applicable to variant 4 and available for consumers to use today”.

The major issue with this newest flaw is a direct link to firmware updates, which means system admins and others that run major networks will have to choose between security and performance. If Speculative Store Bypass (variant 4) protections are enabled, then system performance can take a significant impact. However, Intel has noted that these protections are disabled by default in updates that have already been issued to OEMs.

“Most leading browser providers have recently deployed mitigations in their Managed Runtimes – mitigations that substantially increase the difficulty of exploiting side channels in a modern web browser. These techniques would likewise increase the difficulty of exploiting a side channel in a browser based on SSB.

Intel has released Beta microcode updates to operating system vendors, equipment manufacturers, and other ecosystem partners adding support for Speculative Store Bypass Disable (SSBD). SSBD provides additional protection by providing a means for system software to completely inhibit a Speculative Store Bypass from occurring if desired. This is documented in whitepapers located at Intel’s Software Side-Channel Security site. Most major operating system and hypervisors will add support for Speculative Store Bypass Disable (SSBD) starting as early as May 21, 2018.”

Intel has stated that this latest security flaw has a “moderate” risk warning, and that has to due with the fact that the majority of the exploits have already been addressed up to this point. The majority of those were initially introduced back in January of this year, tied to security updates related to Specter and Metldown.

As is the case with Spectre and Meltdown, this issue is relevant to all modern processors, including from Intel, AMD, and ARM. If you need a quick refresher on Spectre and Meltdown, check out our FAQ. Apple, for its part, did admit that its iOS and Mac products were vulnerable to these issues earlier this year, but that patches were being rolled out.

Intel, too, noted earlier this year that security updates would make devices basically “immune” to Spectre and Meltdown.

Our Take

It’s good to hear that most of these issues have already been addressed, but it’s sad to see that we’re at a point where these flaws are going to keep cropping up. Still, as long as they continue to get patched, we’ll have to accept it.

[via The Verge; Intel (1); (2)]