Rule:

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Sid:
1811

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Summary:
This event is generated when a remote user has exploited a flaw in a 
local SSH server.

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Impact:
Serious

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Detailed Information:
OpenSSH has a flaw in the challenge-response mechanism when configured 
with either the "PAMAuthenticationViaKbdInt" or the 
"ChallengeResponseAuthentication" options. This flaw can be exploited by
a user who is not authenicated and can lead to the attacker obtaining a 
root shell.

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Affected Systems:
OpenSSH versions 1.2 to 3.3, Solaris 9.0, IBM Linux 
Affinity Toolkit, and HP HP-UX Secure Shell A.03.10.

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Attack Scenarios:
An attacker can cause the service to restart or hang, leaving the 
service unavailable to users.

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Ease of Attack:
Simple. Exploit code available.

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False Positives:
None Known

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False Negatives:
None Known

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Corrective Action:
Upgrade to latest version of OpenSSH

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Contributors:
Sourcefire Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>
Snort documentation contributed by Josh Sakofsky

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Additional References:

Bugtraq:
http://www.securityfocus.com/bid/5093

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