[ GLSA 200609-17 ] OpenSSH: Denial of Service

[GLSA]

Gentoo Linux Security Advisory

Title: OpenSSH: Denial of Service (GLSA 200609-17)
Severity: normal
Exploitable: remote
Date: September 27, 2006
Bug(s): #148228
ID: 200609-17

Synopsis

A flaw in the OpenSSH daemon allows remote unauthenticated attackers to cause a Denial of Service.

Background

OpenSSH is a free suite of applications for the SSH protocol, developed and maintained by the OpenBSD project.

Affected Packages

Package: net-misc/openssh
Vulnerable: < 4.3_p2-r5
Unaffected: >= 4.3_p2-r5
Architectures: All supported architectures


Description

Tavis Ormandy of the Google Security Team discovered a Denial of Service vulnerability in the SSH protocol version 1 CRC compensation attack detector.

Impact

A remote unauthenticated attacker may be able to trigger excessive CPU usage by sending a pathological SSH message, denying service to other legitimate users or processes.

Workaround

The system administrator may disable SSH protocol version 1 in /etc/ssh/sshd_config.

Resolution

All OpenSSH users should upgrade to the latest version: