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Microsoft's 'Meltdown' Patch For Windows 10 Contains a Fatal Flaw (bleepingcomputer.com)
An anonymous reader quotes BleepingComputer: Microsoft's patches for the Meltdown vulnerability have had a fatal flaw all these past months, according to Alex Ionescu, a security researcher with cyber-security firm Crowdstrike. Only patches for Windows 10 versions were affected, the researcher wrote today in a tweet. Microsoft quietly fixed the issue on Windows 10 Redstone 4 (v1803), also known as the April 2018 Update, released on Monday.
"Welp, it turns out the Meltdown patches for Windows 10 had a fatal flaw: calling NtCallEnclave returned back to user space with the full kernel page table directory, completely undermining the mitigation," Ionescu wrote. Ionescu pointed out that older versions of Windows 10 are still running with outdated and bypass-able Meltdown patches.
Wednesday Microsoft issued a security update, but it wasn't to backport the "fixed" Meltdown patches for older Windows 10 versions. Instead, the emergency update fixed a vulnerability in the Windows Host Compute Service Shim (hcsshim) library (CVE-2018-8115) that allows an attacker to remotely execute code on vulnerable systems.
"Welp, it turns out the Meltdown patches for Windows 10 had a fatal flaw: calling NtCallEnclave returned back to user space with the full kernel page table directory, completely undermining the mitigation," Ionescu wrote. Ionescu pointed out that older versions of Windows 10 are still running with outdated and bypass-able Meltdown patches.
Wednesday Microsoft issued a security update, but it wasn't to backport the "fixed" Meltdown patches for older Windows 10 versions. Instead, the emergency update fixed a vulnerability in the Windows Host Compute Service Shim (hcsshim) library (CVE-2018-8115) that allows an attacker to remotely execute code on vulnerable systems.
I think Microsoft views disabling servers as less worse than leaving them with a security problem. Just sucks for us since my company's web site is down after apply new Microsoft updates. I'm probably going to lose my job over this which sucks, but I did put in writing in an email that our staging systems wouldn't boot after installing the latest Windows updates.