Jan 11 2018

Here’s how, and why, the Spectre and Meltdown patches will hurt performance

Enlarge (credit: Aurich / Getty)

As the industry continues to grapple with the Meltdown and Spectre attacks, operating system and browser developers in particular are continuing to develop and test schemes to protect against the problems. Simultaneously, microcode updates to alter processor behavior are also starting to ship.

Since news of these attacks first broke, it has been clear that resolving them is going to have some performance impact. Meltdown was presumed to have a substantial impact, at least for some workloads, but Spectre was more of an unknown due to its greater complexity. With patches and microcode now available (at least for some systems), that impact is now starting to become clearer. The situation is, as we should expect with these twin attacks, complex.

To recap: modern high-performance processors perform what is called speculative execution. They will make assumptions about which way branches in the code are taken and speculatively compute results accordingly. If they guess correctly, they win some extra performance; if they guess wrong, they throw away their speculatively calculated results. This is meant to be transparent to programs, but it turns out that this speculation slightly changes the state of the processor. These small changes can be measured, disclosing information about the data and instructions that were used speculatively.

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Jan 09 2018

Bad docs and blue screens make Microsoft suspend Spectre patch for AMD machines

An Athlon 64 purchased in 2007. (credit: Fred)

Microsoft has suspended delivering the latest Windows update to certain systems with AMD processors after reports that the update was causing the machines to crash with a blue screen of death when booting. The update contains countermeasures against both the Meltdown and Spectre attacks; although AMD systems are not affected by Meltdown, they're vulnerable to Spectre.

Withdrawing or suspending delivery of Windows Updates is not uncommon; while there is some testing done by Microsoft, releasing things to a wider audience does from time to time unearth incompatibilities or bugs within the update. What is uncommon is that Microsoft is not merely suspending this update; the company has also outlined why. Specifically, Microsoft writes that:

After investigating, Microsoft has determined that some AMD chipsets do not conform to the documentation previously provided to Microsoft to develop the Windows operating system mitigations to protect against the chipset vulnerabilities known as Spectre and Meltdown.

This is an unusual act of buck-passing.

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Jan 03 2018

“Meltdown” and “Spectre”: Every modern processor has unfixable security flaws

Windows, Linux, and macOS have all received security patches that significantly alter how the operating systems handle virtual memory in order to protect against a hitherto undisclosed flaw. This is more than a little notable; it's been clear that Microsoft and the Linux kernel developers have been informed of some non-public security issue and have been rushing to fix it. But nobody knew quite what the problem was, leading to lots of speculation and experimentation based on pre-releases of the patches.

Now we know what the flaw is. And it's not great news, because there are in fact two related families of flaws with similar impact, and only one of them has any easy fix.

The flaws have been named Meltdown and Spectre. Meltdown was independently discovered by three groups—researchers from the Technical University of Graz in Austria, German security firm Cerberus Security, and Google's Project Zero. Spectre was discovered independently by Project Zero and independent researcher Paul Kocher.

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Nov 14 2017

Krebs on Security 2017-11-14 19:12:32

It’s Nov. 14 — the second Tuesday of the month (a.k.a. “Patch Tuesday) — and Adobe and Microsoft have issued gobs of security updates for their software. Microsoft’s 11 patch bundles fix more than four-dozen security holes in various Windows versions and Office products — including at least four serious flaws that were publicly disclosed prior to today. Meanwhile, Adobe’s got security updates available for a slew of titles, including Flash Player, Photoshop, Reader and Shockwave.

Four of the vulnerabilities Microsoft fixed today have public exploits, but they do not appear to be used in any active malware campaigns, according to Gill Langston at security vendor Qualys. Perhaps the two most serious flaws likely to impact Windows end users involve vulnerabilities in Microsoft browsers Internet Explorer and Edge.

Qualys’ Langston reminds us that on last Patch Tuesday, Microsoft quietly released the fix for CVE-2017-13080, widely known as the KRACK vulnerability in WPA2 wireless protocol, but did not make it known until a week later, when the vulnerability was publicly disclosed. Check out the Qualys blog and this post from Ivanti for more on this month’s patches from Redmond. Otherwise, visit Windows Update sometime soon (click the Start/Windows button, then type Windows Update).

Adobe issued patches to fix at least 62 security vulnerabilities in its products, including several critical bugs in Adobe Flash Player and Reader/Acrobat.  The Flash Player update brings the browser plugin to v. on Windows, Mac, Linux and Chrome OS.

Windows users who browse the Web with anything other than Internet Explorer may need to apply the Flash patch twice, once with IE and again using the alternative browser (Firefox, Opera, e.g.).

Chrome and IE should auto-install the latest Flash version on browser restart (users may need to manually check for updates and/or restart the browser to get the latest Flash version). Chrome users may need to restart the browser to install or automatically download the latest version.

When in doubt, click the vertical three dot icon to the right of the URL bar, select “Help,” then “About Chrome”: If there is an update available, Chrome should install it then. Chrome will replace that three dot icon with an up-arrow inside of a circle when updates are waiting to be installed.

Standard disclaimer: Because Flash remains such a security risk, I continue to encourage readers to remove or hobble Flash Player unless and until it is needed for a specific site or purpose. More on that approach (as well as slightly less radical solutions ) can be found in A Month Without Adobe Flash Player. The short version is that you can probably get by without Flash installed and not miss it at all.

For readers still unwilling to cut the cord, there are half-measures that work almost as well. Fortunately, disabling Flash in Chrome is simple enough. Paste “chrome://settings/content” into a Chrome browser bar and then select “Flash” from the list of items. By default it should be set to “Ask first” before running Flash, although users also can disable Flash entirely here or whitelist and blacklist specific sites.

Another, perhaps less elegant, solution is to keep Flash installed in a browser that you don’t normally use, and then to only use that browser on sites that require it.