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Ubuntu 18.04 LTS USN-6560-2 critical: OpenSSH protocol attack mitigation

ubuntu
Calendar Grey January 11, 2024
Dist Ubuntu Esm H88
Security Notice USN-6560-2 for Ubuntu highlights critical security issues in OpenSSH with necessary mitigation steps.
Several security issues were fixed in OpenSSH.

Summary

Several security issues were fixed in OpenSSH.

Software Description:

- openssh: secure shell (SSH) for secure access to remote machines

Details:

USN-6560-1 fixed several vulnerabilities in OpenSSH. This update provides

the corresponding update for Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.

Original advisory details:

Fabian Bäumer, Marcus Brinkmann, Jörg Schwenk discovered that the SSH

protocol was vulnerable to a prefix truncation attack. If a remote attacker

was able to intercept SSH communications, extension negotiation messages

could be truncated, possibly leading to certain algorithms and features

being downgraded. This issue is known as the Terrapin attack. This update

adds protocol extensions to mitigate this issue. (CVE-2023-48795)

It was discovered that OpenSSH incorrectly handled user names or host names

with shell metacharacters. An attacker could possibly use this issue to

perform OS command injection. This only affected Ubuntu 18.04 LT...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory remote access system update openssh ubuntu protocol attack

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
  openssh-client                  1:7.6p1-4ubuntu0.7+esm3
  openssh-server                  1:7.6p1-4ubuntu0.7+esm3

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
  openssh-client                  1:7.2p2-4ubuntu2.10+esm5
  openssh-server                  1:7.2p2-4ubuntu2.10+esm5

In general, a standard system update will make all the necessary changes.

References

https://ubuntu.com/security/notices/USN-6560-2

https://ubuntu.com/security/notices/USN-6560-1

CVE-2023-48795, CVE-2023-51385

Severity
critical
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Ubuntu Security Notice USN-6560-2

Topics%20covered

Topics Covered

security advisory remote access system update openssh ubuntu protocol attack

Package Information

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