Rule:

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Sid:

1810

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Summary:
This event is generated when an attack against an OpenSSH (v2.9 - 3.3) server using the GOBBLES exploit was successful.

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Impact:
Full system compromise with escalated privileges.

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Detailed Information:
This attack exploits the "remote challenge-response" vulnerability in older versions of OpenSSH servers. The vulnerability affects OpenSSH versions 2.9 through 3.3 that have the challenge response option enabled and that also use SKEY or BSD_AUTH authentication. 

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Affected Systems:
Any UNIX Servers that have vulnerable OpenSSH daemon running including but not limited to the following:
	Mandrake Soft Linux 7.1, 7.2, 8.0, 8.1, 8.2
	OpenBSD 3.0, 3.1
	Red Hat Linux 7.0, 7.1, 7.2, 7.3
	SuSe Linux 6.4, 7.0, 7.1, 7.2, 7.3

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Attack Scenarios:
An attacker first determines what version of OpenSSH the targeted machine is running then launches a publicly available GOBBLES exploit script against it.


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Ease of Attack:
Simple.

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False Positives:
None known.

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False Negatives:
None known.

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Corrective Action:
Disable S/Key and BSD Authentication by modifying the sshd_config file

	ChallengeResponseAuthentication no

Upgrade to OpenSSH v3.4 or later

Apply the appropriate vendor supplied patch.

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Contributors:
Sourcefire Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>
Snort documentation contributed by Nawapong Nakjang (tony@ksc.net, tonie@thai.com)

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Additional References:

CERT:
http://www.cert.org/advisories/CA-2002-18.html

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