OpenSSH 9.6: Critical Advisory on Terrapin Attack and Security Update

OpenSSH

The Discovery 

Multiple severe vulnerabilities have been discovered and mitigated in OpenSSH, a popular open-source implementation of the Secure Shell (SSH) protocol. The most notorious of these bugs is the “Terrapin vulnerability,” tracked as CVE-2023-48795, which allows a man-in-the-middle (MITM) attacker to effect a limited break of the integrity of the early encrypted SSH transport protocol by sending extra messages before the commencement of encryption, and deleting an equal number of consecutive messages immediately after encryption starts.

The Impact

The implications of the Terrapin attack are far-reaching, given OpenSSH’s widespread use in secure data communications. An attack could result in the compromise of sensitive data transmitted across networks.

The Fix

A critical update for OpenSSH, OpenSSH 9.6, has been released to mitigate the Terrapin bug and several other recent flaws found in OpenSSH. Given these vulnerabilities’ severe threat to affected systems, if left unpatched, we strongly recommend all impacted users update to version 9.6 immediately to protect against man-in-the-middle attacks leading to data compromise.

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Intel Microcode

The Discovery 

Not long after the notorious “Reptar” Intel Microcode privilege escalation bug dominated security news headlines, another significant microcode privilege escalation flaw was found. It was discovered that a sequence of processor instructions leads to unexpected behavior for some Intel(R) Processors that may allow an authenticated user to escalate privileges (CVE-2023-23583). The National Vulnerability Database has classified the severity of this flaw as “High” due to its significant threat to the availability of impacted systems and the confidentiality of sensitive data.

The Impact

This vulnerability could result in the disclosure of sensitive information or denial of denial-of-service attacks, leaving critical systems unavailable.

The Fix

Essential Intel Microcode updates have been released to mitigate this critical bug. Given this vulnerability’s severe threat to affected systems, if left unpatched, we urge all impacted users to update as soon as possible. Doing so will protect against system downtime and information compromise.

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HAProxy

The Discovery 

Have you updated to fix CVE-2023-45539, a recent HAProxy vulnerability that threatens impacted users’ sensitive information? It was discovered that the HAProxy load balancing reverse proxy incorrectly handled URI components containing the hash character. Distros continue to release updates for this flaw, which has received a National Vulnerability Database severity rating of “High” due to its significant confidentiality threat to affected systems and how straightforward it is for attackers to exploit.

The Impact

A remote attacker could exploit this bug to obtain sensitive data or bypass specific path_end rules.

The Fix

An important HAProxy update has been released to fix this severe bug. Given this vulnerability's damaging repercussions on impacted systems, if left unpatched, we urge all affected users to update now to protect against data compromise.

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