FreeBSD : openssh -- multiple vulnerabilities (32db37a5-50c3-11db-acf3-000c6ec775d9)

High Nessus Plugin ID 22488


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


Problem Description The CRC compensation attack detector in the sshd(8) daemon, upon receipt of duplicate blocks, uses CPU time cubic in the number of duplicate blocks received. [CVE-2006-4924]

A race condition exists in a signal handler used by the sshd(8) daemon to handle the LoginGraceTime option, which can potentially cause some cleanup routines to be executed multiple times. [CVE-2006-5051] Impact An attacker sending specially crafted packets to sshd(8) can cause a Denial of Service by using 100% of CPU time until a connection timeout occurs. Since this attack can be performed over multiple connections simultaneously, it is possible to cause up to MaxStartups (10 by default) sshd processes to use all the CPU time they can obtain.

The OpenSSH project believe that the race condition can lead to a Denial of Service or potentially remote code execution, but the FreeBSD Security Team has been unable to verify the exact impact.
[CVE-2006-5051] Workaround The attack against the CRC compensation attack detector can be avoided by disabling SSH Protocol version 1 support in sshd_config(5).

There is no workaround for the second issue.


Update the affected packages.

See Also

Plugin Details

Severity: High

ID: 22488

File Name: freebsd_pkg_32db37a550c311dbacf3000c6ec775d9.nasl

Version: $Revision: 1.16 $

Type: local

Published: 2006/10/02

Modified: 2016/12/08

Dependencies: 12634

Risk Information

Risk Factor: High


Base Score: 9.3

Temporal Score: 8.1

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

Temporal Vector: CVSS2#E:ND/RL:OF/RC:C

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:openssh, p-cpe:/a:freebsd:freebsd:openssh-portable, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info

Exploit Available: false

Exploit Ease: No known exploits are available

Patch Publication Date: 2006/09/30

Vulnerability Publication Date: 2006/09/25

Reference Information

CVE: CVE-2006-4924, CVE-2006-5051

BID: 20216, 20241

OSVDB: 29152, 29264, 29266

FreeBSD: SA-06:22.openssh

CWE: 362, 399