SB2023121949 - Ubuntu update for openssh

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Main Vulnerability Database SB2023121949

SB2023121949 - Ubuntu update for openssh

Published: December 19, 2023 Updated: January 31, 2025

Security Bulletin ID SB2023121949
Severity
Low
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 secuirty vulnerabilities.


1) Inadequate encryption strength (CVE-ID: CVE-2023-48795)

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to incorrect implementation of the SSH Binary Packet Protocol (BPP), which mishandles the handshake phase and the use of sequence numbers. A remote attacker can perform MitM attack and delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.

The vulnerability was dubbed "Terrapin attack" and it affects both client and server implementations.


2) Credentials management (CVE-ID: CVE-2023-28531)

The vulnerability allows a remote user to bypass implemented security restrictions.

the vulnerability exists due to a logic error in ssh-add when adding smartcard keys to ssh-agent with the per-hop destination constraints. As a result, the keys are added without constraints.


Remediation

Install update from vendor's website.

References