intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

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SpookyWatcher
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intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

Post by SpookyWatcher »

I'm catching wind that this latest microdcode disables hyperthreading? I have the skylake i7-6700k and my google foo isn't turning up much since the initial report. I'm really interested in possible performance hit.

If it does disable hyperthreading, did anyone notice a remarkable drop in performance? I've held back the update...just wondering if I should let it update. Is the vulnerability really that bad or is it remote chance. Not really interested in kicking my cpu in the nuts for an extremely remote vulnerability.

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Re: intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

Post by gm10 »

Disabling hyper-threading is the recommended course of action on affected processors but it does not happen by default because preferably you do it in your BIOS/UEFI. For further information see https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/MDS and https://www.intel.com/content/www/us/en ... y/mds.html.
Last edited by gm10 on Sun Jun 16, 2019 2:39 pm, edited 1 time in total.
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Re: intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

Post by Pjotr »

SpookyWatcher wrote:
Sun Jun 16, 2019 2:21 pm
Is the vulnerability really that bad
Yes:
https://www.zdnet.com/article/intel-cpu ... el-attack/
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Re: intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

Post by SpookyWatcher »

Is it more of a vulnerability on my cloud servers? I have no problem with throwing all patches at those regardless of performance hit.

But what about my home box? Is it vulnerable too? How would it be vulnerable? I'm digging as hard as I can...but nothing is mentioned exactly how the attack could be successful. Would they have to have access to my home box? Or can it be attacked with malicious javascript from injected ad on normally safe website?

Really trying to understand, but there isn't much to go on.

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Re: intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

Post by Pjotr »

This looks bad for home boxes:
While weaponizing MDS vulnerabilities ultimately requires the ability to locally execute code, JavaScript proofs of concept exist, making the attack possible to exploit on maliciously-crafted web pages. When exploited, malicious actors can extract data from other programs on the same machine, across security boundaries, including SGX enclaves.

Exploitation of MDS vulnerabilities can be performed untraceably—that is, without leaving evidence of an exploit in system logs.
Source: https://www.techrepublic.com/article/wh ... -meltdown/
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Re: intel microcode 3.20190514.0ubuntu0.16.04.2 disables hyperthreading?

Post by SpookyWatcher »

You're absolutely right. <sigh>

Well time to break out my other mobo and overclock to compensate for the performance hit.

Thx Pjotr

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