Debian DSA-1638-1 : openssh - denial of service

high Nessus Plugin ID 34223

Synopsis

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

Description

It has been discovered that the signal handler implementing the login timeout in Debian's version of the OpenSSH server uses functions which are not async-signal-safe, leading to a denial of service vulnerability (CVE-2008-4109 ).

The problem was originally corrected in OpenSSH 4.4p1 (CVE-2006-5051 ), but the patch backported to the version released with etch was incorrect.

Systems affected by this issue suffer from lots of zombie sshd processes. Processes stuck with a '[net]' process title have also been observed. Over time, a sufficient number of processes may accumulate such that further login attempts are impossible. Presence of these processes does not indicate active exploitation of this vulnerability.
It is possible to trigger this denial of service condition by accident.

Solution

Upgrade the openssh packages.

For the stable distribution (etch), this problem has been fixed in version 4.3p2-9etch3.

Plugin Details

Severity: High

ID: 34223

File Name: debian_DSA-1638.nasl

Version: 1.18

Type: local

Agent: unix

Family: Debian Local Security Checks

Published: 9/17/2008

Updated: 1/4/2021

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 9.3

Temporal Score: 6.9

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

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:4.0, p-cpe:/a:debian:debian_linux:openssh

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

Exploit Ease: No known exploits are available

Patch Publication Date: 9/16/2008

Reference Information

CVE: CVE-2006-5051, CVE-2008-4109

BID: 20241

CWE: 264, 362

DSA: 1638

Detections

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