Bug 2255850 (CVE-2023-51767)

Summary: CVE-2023-51767 openssh: authentication bypass via row hammer attack
Product: [Other] Security Response Reporter: ybuenos
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: askrabec, djm, jalviso, oarribas, pdwyer, prodsec-ir-bot, saroy
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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An authentication bypass vulnerability was found in a modified version of OpenSSH. When common types of DRAM memory are used, it might allow row hammer attacks because the integer value of authenticated authpassword does not resist flips of a single bit. Exploiting a Rowhammer-style attack to flip bits in memory, forces successful authentication by setting the return code to 0.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2255851    
Bug Blocks: 2255855    

Description ybuenos 2023-12-25 19:41:07 UTC 
OpenSSH through 9.6, when common types of DRAM are used, might allow row hammer attacks (for authentication bypass) because the integer value of authenticated in mm_answer_authpassword does not resist flips of a single bit. NOTE: this is applicable to a certain threat model of attacker-victim co-location in which the attacker has user privileges.

https://arxiv.org/abs/2309.02545
https://github.com/openssh/openssh-portable/blob/8241b9c0529228b4b86d88b1a6076fb9f97e4a99/auth-passwd.c#L77
https://github.com/openssh/openssh-portable/blob/8241b9c0529228b4b86d88b1a6076fb9f97e4a99/monitor.c#L878
Comment 1 ybuenos 2023-12-25 19:41:22 UTC 
Created openssh tracking bugs for this issue:

Affects: fedora-all [bug 2255851]
Comment 5 Damien Miller 2024-01-16 07:32:33 UTC 
FYI https://bugzilla.mindrot.org/show_bug.cgi?id=3656