More information, including two papers on the CPU issues, has been released. The papers on the two bugs, called “Meltdown” and “Spectre” are available from: https://meltdownattack.com/. These papers are technical descriptions of the bugs. Meltdown works on Intel processors only, Spectre works on Intel, AMD, and ARM processors.

Microsoft released patches today – the patch is not enabled by default and has to be enabled manually after the patch is applied. In addition, the patch will not be available for systems that are running incompatible anti-virus – some AV packages make calls into kernel memory that will cause a blue-screen-of-death if the patch is applied and enabled. More information from Microsoft is available here:
https://support.microsoft.com/en-us/help/4072699/important-information-regarding-the-windows-security-updates-released

A security researcher has a Google Docs spreadsheet of the status of AV products here:
https://docs.google.com/spreadsheets/d/184wcDt9I9TUNFFbsAVLpzAtckQxYiuirADzf3cL42FQ/edit#gid=0

Windows Server Guidance to protect against the speculative execution side-channel vulnerabilities:
https://support.microsoft.com/en-us/help/4072698/windows-server-guidance-to-protect-against-the-speculative-execution-s

Windows Client Guidance for IT Pros to protect against speculative execution side-channel vulnerabilities:
https://support.microsoft.com/en-us/help/4073119/windows-client-guidance-for-it-pros-to-protect-against-speculative-exe

List of Meltdown and Spectre Vulnerability Advisories, Patches, & Updates:
https://www.bleepingcomputer.com/news/security/list-of-meltdown-and-spectre-vulnerability-advisories-patches-and-updates/

A Simple Explanation of the Differences Between Meltdown and Spectre:
https://danielmiessler.com/blog/simple-explanation-difference-meltdown-spectre/

Reportedly MacOS 10.13.2 has the fixes in it and was released December 6, 2017.

A flaw in the design of Intel’s CPU chips is forcing large kernel updates for Windows, Linux, and MacOS systems. This bug affects all Intel processors produced over the last 10 years (at least), and is not fixable via firmware updates. Expect the changes to be released very soon.

The flaw allows normal user programs to possibly access protected kernel memory, which should not be allowed under normal circumstances. This flaw could allow someone to gain access to items in memory that should not be seen by user programs, such as the contents of other user’s files, encryption keys, etc. Since this bug will require re-architecting how the kernel is protected in memory, there will be a performance hit when switching between the kernel and user processes. Some estimates of the performance hit are 5-30% slowdown.

There’s a reasonable chance that the changes will have bugs that could cause system problems, but you should install the updates reasonably soon after they are released. The bug impacts Azure, Amazon, and Google cloud environments. You can expect those providers to schedule maintenance and reboots soon to implement the fixes in their environments. AMD has stated that their CPUs are not affected by this bug.

More information is available from: https://www.theregister.co.uk/2018/01/02/intel_cpu_design_flaw/