CPU Fixes for Spectre Variant 2 Roll Out from AMD

Chipmaker AMD recently issued microcode updates to its original equipment manufacturing (OEM) partners that protect Windows 10 systems against Spectre variant 2 attack methods.

AMD had already released microcode updates for Spectre variant 2 on Linux systems earlier this year. Updates for Windows Server 2016 are still at the testing and validation stage, according to an AMD spokesperson.

Typically, these microcode updates get released by chipmakers to PC and server OEMs. After OEM testing, they get publicly released.

These releases are tied to a general industry response to the Meltdown and Spectre attack methods, first publicized by Google Project Zero researchers back in early January. Adding protections against the attack methods basically is a two-step process that entails applying firmware updates to chips along with updates to operating systems (both Linux and Windows systems).

To recap, researchers found three variants of the two attack methods, which overall affect all modern CPUs on Linux and Windows operating systems:

  • Variant 1: bounds check bypass (CVE-2017-5753) labeled "Spectre"
  • Variant 2: branch target injection (CVE-2017-5715) labeled "Spectre"
  • Variant 3: rogue data cache load (CVE-2017-5754) labeled "Meltdown"

For AMD-based systems, Spectre variant 1 gets fixed through an operating system update, which apparently was released back in January. The Meltdown attack method doesn't affect AMD processors, according to AMD. Meltdown only pertains to Intel chips and some ARM chips.

Microsoft's Jan. 3 OS fix for the Meltdown and Spectre attack methods initially caused some AMD machines to become unbootable, but the issue was subsequently resolved. In the case of AMD-based machines, Microsoft's Jan. 3 Windows security update likely contained the Spectre variant 1 patch.

Microsoft's April 10 Windows security update similarly is bringing an OS fix to Windows 10 version 1709, but this fix is for Spectre variant 2, according to AMD's announcement:

Microsoft is releasing an operating system update containing Variant 2 (Spectre) mitigations for AMD users running Windows 10 (version 1709) today. Support for these mitigations for AMD processors in Windows Server 2016 is expected to be available following final validation and testing.

AMD has now released microcode updates for Spectre variant 2 for its processors "dating back to the first 'Bulldozer' core products introduced in 2011," according to the announcement.

About the Author

Kurt Mackie is senior news producer for 1105 Media's Converge360 group.

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