SB2024070502 - Gentoo update for PuTTY
Published: July 5, 2024 Updated: January 31, 2025
Breakdown by Severity
- 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) Cryptographic issues (CVE-ID: CVE-2024-31497)
The vulnerability allows a remote attacker to recover NIST P-521 private keys.
The vulnerability exists due to the PuTTY client and all related components generate heavily biased ECDSA nonces in the case of NIST P-521. A remote attacker can recover the NIST P-521 private key using roughly 60 valid ECDSA signatures generated by any PuTTY component under the same key.
Note, if the key has been used to sign arbitrary data (e.g., git commits by forwarding Pageant to a development host), the publicly available signatures (e.g., on GitHub) can be used as well.
Remediation
Install update from vendor's website.