oss-security - Re: CVE-2023-23583: Intel - Denial of Service

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Message-ID: <7a2b4406-6f0e-4e4f-be43-a0ec27404063@ipsumj.de>
Date: Tue, 14 Nov 2023 20:19:05 +0100
From: HW42 <hw42@...umj.de>
To: oss-security@...ts.openwall.com, Solar Designer <solar@...nwall.com>,
 Antonio Gomez Iglesias <antonio.gomez.iglesias@...el.com>
Cc: Tavis Ormandy <taviso@...il.com>
Subject: Re: CVE-2023-23583: Intel - Denial of Service -
 Privilege Escalation (Reptar)

Solar Designer:
> On Tue, Nov 14, 2023 at 10:31:51AM -0800, Antonio Gomez Iglesias wrote:
>> Name of the issue: Redundant Prefix Issue
>>
>> Description of the issue
>> Under certain microarchitectural conditions, Intel has identified cases
>> where execution of an instruction (REP MOVSB) encoded with a redundant
>> REX prefix may result in unpredictable system behavior resulting in a
>> system crash/hang, or, in some limited scenarios, may allow escalation
>> of privilege from CPL3 to CPL0.
>> This Redundant Prefix Issue is assigned CVE-2023-23583 with a CVSS Base
>> Score of 8.8 High CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
>>
>> Mitigation
>> Intel is providing a microcode update to mitigate this issue: https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/releases/tag/microcode-20231114
> 
> Thank you, Antonio!
> 
> Here's a writeup and reproducer tool by Tavis Ormandy:
> 
> https://lock.cmpxchg8b.com/reptar.html
> 
> The GitHub release page above links to Intel security advisory:
> 
> https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00950.html
> 
> which specifies what CPU generations are affected (from 10th generation
> Intel Core or 3rd generation Xeon Scalable to current), and links to a
> table with "an exhaustive list of processors" matched against this issue
> and previously disclosed issues:
> 
> https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html
> 
> It also says "Please refer to the technical paper here for additional
> information", where "here" is a link supposedly to "the technical
> paper", but it's a non-existent page currently, so I'm not posting the
> URL yet (not sure if it'll stay the same when the page is published).

I think that link should point to 

https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/redundant-prefix-issue.html

This one can be found in the affected processors table.

Simon


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