Microsoft Delivers Emergency Windows 10 Patch for 'Meltdown' CPU Bug

Microsoft rushes to protect Windows 10 users and its own cloud servers from critical processor flaws.

Windows 10 security

Soon after returning from the holidays, IT professionals were confronted with a severe memory-isolation flaw in Intel processors called Meltdown. Present in just about every processor shipped by the chipmaker since 1995, the flaw can be used to unravel some of the most critical security mechanisms used in operating system software.

"Meltdown breaks the most fundamental isolation between user applications and the operating system," cautions the Meltdown security advisory. "This attack allows a program to access the memory, and thus also the secrets, of other programs and the operating system."

Affected devices run the gamut, from laptops to high-end cloud servers, with the exception of systems with pre-2013 Itanium and Atom processors. The same advisory warns of Spectre, a similar memory-isolation flaw that affects processors from Intel, Advanced Micro Devices and Arm. Although Spectre is harder to exploit, it's also tougher to mitigate.

Microsoft, meanwhile, is already on the case.

"We're aware of this industry-wide issue and have been working closely with chip manufacturers to develop and test mitigations to protect our customers," said a Microsoft spokesperson in an email message sent to eWEEK. "We are in the process of deploying mitigations to cloud services and released security updates on January 3 to protect Windows customers against vulnerabilities affecting supported hardware chips from Intel, ARM, and AMD."

Indeed, Microsoft deviated from its time-honored "Patch Tuesday" schedule to issue an emergency patch to Windows 10 users on Jan. 3, which is available through Windows Update. The patch will be available to Windows 7 and 8 users on Jan. 9.

If there's a silver lining, it's that the flaws appear to have been discovered and are in the process of being addressed before they pose a widespread risk to Windows users. "We have not received any information to indicate that these vulnerabilities had been used to attack our customers," the Microsoft spokesperson added.

Chipmakers Respond

On Jan. 3, Intel officially addressed the issue in a statement posted to its website. Reports stating that the flaw is unique to Intel chips are incorrect, the company argued. (This is true for Spectre, but Meltdown has only been verified to work on Intel chips.)

Intel has started rolling out software and firmware upgrades of its own. The company also addressed concerns about the performance hit that users may experience after applying patches and other mitigations. "Contrary to some reports, any performance impacts are workload-dependent, and, for the average computer user, should not be significant and will be mitigated over time."

AMD is downplaying the effects of the processor flaws. In response to Google Project Zero's findings on Meltdown and Spectre, the company said that software updates or differences in the company's chip architectures lessen the risk to systems running on AMD processors.

Arm released new online documentation showing that most of its processor designs are unaffected by the flaws. "It is important to note that this method is dependent on malware running locally which means it's imperative for users to practice good security hygiene by keeping their software up-to-date and avoid suspicious links or downloads," the company advised, before providing guidance for affected users.

Pedro Hernandez

Pedro Hernandez

Pedro Hernandez is a contributor to eWEEK and the IT Business Edge Network, the network for technology professionals. Previously, he served as a managing editor for the network of...