FreeBSD extra ssh port listening flaw
| freebsd-ssh-ports (4638) |  Low Risk |
Description:
A vulnerability exists in FreeBSD that can allow users with valid SSH (Secure Shell) credentials to access the ssh server on a non-standard port, which could lead to the bypassing of IP address access controls on the standard SSH port. This flaw is due to a faulty patch added to the FreeBSD SSH port on January 14th, 2000.
Platforms Affected:
- FreeBSD, FreeBSD 4.0
Remedy:
Upgrade your ports collection and rebuild the ssh port, as listed in FreeBSD, Inc. Security Advisory FreeBSD-SA-00:21. See References.
— OR —
Download a new port skeleton for the ssh port from, and use it to rebuild the port, as listed in FreeBSD, Inc. Security Advisory FreeBSD-SA-00:21. See References.
— OR —
Use one of the following workarounds, as listed in FreeBSD, Inc. Security Advisory FreeBSD-SA-00:21 (see References):
- In /usr/local/etc/sshd_config, comment out the line "Port 722", then restart sshd.
- Limit connections to port 722 by adding filtering rules to your perimeter firewall, or on the local system (using ipfw or ipf).
- Uninstall the ssh port/package.
Consequences:
References:
- FreeBSD Security Advisory FreeBSD-SA-00:21, ssh port listens on extra network port [REVISED] at ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-00:21.ssh.asc.v1.1.
- BID-1323: FreeBSD SSH Port Extra Network Port Listening Vulnerability
- CVE-2000-0532: A FreeBSD patch for SSH on 2000-01-14 configures ssh to listen on port 722 as well as port 22, which might allow remote attackers to access SSH through port 722 even if port 22 is otherwise filtered.
- OSVDB ID: 1387: FreeBSD SSH Port Extra Network Port
Reported:
Jun 07, 2000
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