OpenSSH: Denial of Service — GLSA 200609-17

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

Affected Packages

net-misc/openssh on all architectures
Affected versions < 4.3_p2-r5
Unaffected versions >= 4.3_p2-r5

Background

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

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:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-misc/openssh-4.3_p2-r5"

References

Release Date
September 27, 2006

Latest Revision
September 27, 2006: 02

Severity
normal

Exploitable
remote

Bugzilla entries