Category: Patches

Apr 11 2018

AMD systems gain Spectre protection with latest Windows fixes

Enlarge / An AMD Ryzen. (credit: Fritzchens Fritz)

The latest Windows 10 fixes, released as part of yesterday's Patch Tuesday, enable protection against the Spectre variant 2 attacks on systems with AMD processors.

Earlier this year, attacks that exploit the processor's speculative execution were published with the names Meltdown and Spectre, prompting a reaction from hardware and software companies. AMD chips are immune to Meltdown but have some vulnerability to the two Spectre variants. Spectre variant 1 requires application-level fixes; variant 2 requires operating system-level alterations.

Both Intel and AMD have released microcode updates to alter their processor behavior to give operating systems the control necessary to protect against Spectre variant 2. Microsoft has been shipping the Intel microcode, along with the operating system changes necessary to use the microcode's new features, for several weeks now; with yesterday's patch, similar protections are now enabled on AMD machines.

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Mar 13 2018

Patch Tuesday drops the mandatory antivirus requirement after all

(credit: amalthya / Flickr)

In the immediate aftermath of the Spectre and Meltdown attacks, Microsoft created an unusual stipulation for Windows patches: systems would only receive the fixes if they had antivirus software installed and if that antivirus software created a special entry in the registry to indicate that it's compatible with the Windows fixes.

This was due to the particularly invasive nature of the Meltdown fix: Microsoft found that certain antivirus products manipulated Windows' kernel memory in unsupported ways that would crash systems with the Meltdown fix applied. The registry entry was a way for antivirus software to positively affirm that it was compatible with the Meltdown fix; if that entry was absent, Windows assumed that incompatible antivirus software was installed and hence did not apply the security fix.

This put systems without any antivirus software at all in a strange position: they too lack the registry entries, so they'd be passed over for fixes, even though they don't, in fact, have any incompatible antivirus software.

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Jan 05 2018

Meltdown and Spectre: Here’s what Intel, Apple, Microsoft, others are doing about it

Enlarge (credit: Jen)

The Meltdown and Spectre flaws—two related vulnerabilities that enable a wide range of information disclosure from every mainstream processor, with particularly severe flaws for Intel and some ARM chips—were originally revealed privately to chip companies, operating system developers, and cloud computing providers. That private disclosure was scheduled to become public some time next week, enabling these companies to develop (and, in the case of the cloud companies, deploy) suitable patches, workarounds, and mitigations.

With researchers figuring out one of the flaws ahead of that planned reveal, that schedule was abruptly brought forward, and the pair of vulnerabilities was publicly disclosed on Wednesday, prompting a rather disorderly set of responses from the companies involved.

There are three main groups of companies responding to the Meltdown and Spectre pair: processor companies, operating system companies, and cloud providers. Their reactions have been quite varied.

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Jun 19 2017

Serious privilege escalation bug in Unix OSes imperils servers everywhere

Enlarge (credit: Victorgrigas)

A raft of Unix-based operating systems—including Linux, OpenBSD, and FreeBSD—contain flaws that let attackers elevate low-level access on a vulnerable computer to unfettered root. Security experts are advising administrators to install patches or take other protective actions as soon as possible.

Stack Clash, as the vulnerability is being called, is most likely to be chained to other vulnerabilities to make them more effectively execute malicious code, researchers from Qualys, the security firm that discovered the bugs, said in a blog post published Monday. Such local privilege escalation vulnerabilities can also pose a serious threat to server host providers because one customer can exploit the flaw to gain control over other customer processes running on the same server. Qualys said it's also possible that Stack Clash could be exploited in a way that allows it to remotely execute code directly.

"This is a fairly straightforward way to get root after you've already gotten some sort of user-level access," Jimmy Graham, director of product management at Qualys, told Ars. The attack works by causing a region of computer memory known as the stack to collide into separate memory regions that store unrelated code or data. "The concept isn't new, but this specific exploit is definitely new."

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