Debian DSA-5586-1 : openssh - security update

critical Nessus Plugin ID 187213

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Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 11 / 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-5586 advisory.

Several vulnerabilities have been discovered in OpenSSH, an implementation of the SSH protocol suite.
CVE-2021-41617 It was discovered that sshd failed to correctly initialise supplemental groups when executing an AuthorizedKeysCommand or AuthorizedPrincipalsCommand, where a AuthorizedKeysCommandUser or AuthorizedPrincipalsCommandUser directive has been set to run the command as a different user. Instead these commands would inherit the groups that sshd was started with. CVE-2023-28531 Luci Stanescu reported that a error prevented constraints being communicated to the ssh-agent when adding smartcard keys to the agent with per-hop destination constraints, resulting in keys being added without constraints.
CVE-2023-48795 Fabian Baeumer, Marcus Brinkmann and Joerg Schwenk discovered that the SSH protocol is prone to a prefix truncation attack, known as the Terrapin attack. This attack allows a MITM attacker to effect a limited break of the integrity of the early encrypted SSH transport protocol by sending extra messages prior to the commencement of encryption, and deleting an equal number of consecutive messages immediately after encryption starts. Details can be found at https://terrapin-attack.com/ CVE-2023-51384 It was discovered that when PKCS#11-hosted private keys were added while specifying destination constraints, if the PKCS#11 token returned multiple keys then only the first key had the constraints applied. CVE-2023-51385 It was discovered that if an invalid user or hostname that contained shell metacharacters was passed to ssh, and a ProxyCommand, LocalCommand directive or match exec predicate referenced the user or hostname via expansion tokens, then an attacker who could supply arbitrary user/hostnames to ssh could potentially perform command injection. The situation could arise in case of git repositories with submodules, where the repository could contain a submodule with shell characters in its user or hostname. For the oldstable distribution (bullseye), these problems have been fixed in version 1:8.4p1-5+deb11u3. For the stable distribution (bookworm), these problems have been fixed in version 1:9.2p1-2+deb12u2. We recommend that you upgrade your openssh packages. For the detailed security status of openssh please refer to its security tracker page at: https://security- tracker.debian.org/tracker/openssh

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

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

Solution

Upgrade the openssh packages.

For the stable distribution (bookworm), these problems have been fixed in version 1

Plugin Details

Severity: Critical

ID: 187213

File Name: debian_DSA-5586.nasl

Version: 1.7

Type: local

Agent: unix

Family: Debian Local Security Checks

Published: 12/22/2023

Updated: 1/24/2025

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 4.4

Temporal Score: 3.4

Vector: CVSS2#AV:L/AC:M/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2021-41617

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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

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

CVSS Score Source: CVE-2023-28531

CVSS v4

Risk Factor: Critical

Base Score: 9.3

Threat Score: 8.9

Threat Vector: CVSS:4.0/E:P

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS Score Source: CVE-2023-48795

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:ssh-askpass-gnome, cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:openssh-server-udeb, cpe:/o:debian:debian_linux:12.0, p-cpe:/a:debian:debian_linux:ssh, p-cpe:/a:debian:debian_linux:openssh-sftp-server, p-cpe:/a:debian:debian_linux:openssh-server, p-cpe:/a:debian:debian_linux:openssh-tests, p-cpe:/a:debian:debian_linux:openssh-client, p-cpe:/a:debian:debian_linux:openssh-client-udeb

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: 12/22/2023

Vulnerability Publication Date: 9/26/2021

Reference Information

CVE: CVE-2021-41617, CVE-2023-28531, CVE-2023-48795, CVE-2023-51384, CVE-2023-51385

IAVA: 2021-A-0474-S, 2023-A-0152-S, 2023-A-0701-S, 2023-A-0703

Detections

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