Debian dla-3839 : pterm - security update

medium Nessus Plugin ID 200783

Synopsis

The remote Debian host is missing a security-related update.

Description

The remote Debian 10 host has packages installed that are affected by a vulnerability as referenced in the dla-3839 advisory.

- ------------------------------------------------------------------------- Debian LTS Advisory DLA-3839-1 [email protected] https://www.debian.org/lts/security/ Bastien Roucaris June 20, 2024 https://wiki.debian.org/LTS
- -------------------------------------------------------------------------

Package : putty Version : 0.74-1+deb11u1~deb10u2 CVE ID : CVE-2024-31497

A biased ECDSA nonce generation allowed an attacker to recover a user's NIST P-521 secret key via a quick attack in approximately 60 signatures. In other words, an adversary may already have enough signature information to compromise a victim's private key, even if there is no further use of vulnerable PuTTY versions.

This allowed an attacker to (for instance) log in to any servers the victim uses that key for.

To obtain these signatures, an attacker need only briefly compromise any server the victim uses the key to authenticate to.

Therefore, if you have any NIST-P521 ECDSA key, we strongly recommend you to replace it with a freshly new created with a fixed version of putty. Then, to revoke the old public key and remove it from any machine where you use it to login into, so that a signature from the compromised key has no value any more.

The only affected key type is 521-bit ECDSA. That is, a key that appears in Windows PuTTYgen with ecdsa-sha2-nistp521 at the start of the 'Key fingerprint' box, or is described as 'NIST p521', or has an id starting ecdsa-sha2-nistp521 in the SSH protocol or the key file.
Other sizes of ECDSA, and other key algorithms, are unaffected.
In particular, Ed25519 is not affected.

For Debian 10 buster, this problem has been fixed in version 0.74-1+deb11u1~deb10u2.

We recommend that you upgrade your putty packages.

For the detailed security status of putty please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/putty

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade the pterm packages.

See Also

https://security-tracker.debian.org/tracker/source-package/putty

https://security-tracker.debian.org/tracker/CVE-2024-31497

https://packages.debian.org/source/buster/putty

Plugin Details

Severity: Medium

ID: 200783

File Name: debian_DLA-3839.nasl

Version: 1.1

Type: local

Agent: unix

Published: 6/20/2024

Updated: 6/20/2024

Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.1

CVSS v2

Risk Factor: Medium

Base Score: 5.4

Temporal Score: 4.2

Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:N/A:N

CVSS Score Source: CVE-2024-31497

CVSS v3

Risk Factor: Medium

Base Score: 5.9

Temporal Score: 5.3

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:putty-tools, cpe:/o:debian:debian_linux:10.0, p-cpe:/a:debian:debian_linux:putty, p-cpe:/a:debian:debian_linux:pterm, p-cpe:/a:debian:debian_linux:putty-doc

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 6/20/2024

Vulnerability Publication Date: 4/15/2024

Reference Information

CVE: CVE-2024-31497

IAVA: 2024-A-0243