SB2023122405 - Debian update for putty

CSH
CYBERSECURITY HELP
Sign In REGISTER

Main Vulnerability Database SB2023122405

SB2023122405 - Debian update for putty

Published: December 24, 2023 Updated: January 31, 2025

Security Bulletin ID SB2023122405
Severity
Medium
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Remote access
Highest impact Information disclosure

Breakdown by Severity

Medium 50% Low 50%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 secuirty vulnerabilities.


1) Insufficient verification of data authenticity (CVE-ID: CVE-2021-36367)

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to insufficient verification of data source when processing authentication responses. A remote attacker can send a spoofed authentication prompt even after an SSH session has been established with the original server and trick the victim into providing authentication credentials.


2) 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.


Remediation

Install update from vendor's website.

References