Rule:

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Sid:

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Summary:
This event is generated when an attempt is made to exploit an
information disclosure vulnerability associated with a telnet
client.

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Impact:
A successful information disclosure may give an attacker
valuable information about the telnet client such as the
current user or the operating system.

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Detailed Information:
A telnet client and server can negotiate various options such as
the character set to be used in the communication exchange. One
particular option allows a client or server to send new environment
options. Certain telnet clients will respond to a telnet server
that issues a new environment send command for a particular
environment variable, such as the current user.  This information
disclosure can be valuable to a potential attacker.

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Affected Systems:
	Multiple verndors, Microsoft, Sun Microsystems, refer to reference
	information and vendor advisories for details.

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Attack Scenarios:
An attacker can entice a user to a malicious telnet server and attempt
to get the telnet client to respond with a value for an environment
variable.

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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:
Upgrade to the most current non-affected version of the product.

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Contributors:
Sourcefire Vulnerability Research Team
Judy Novak <judy.novak@sourcefire.com>

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Additional References

iDefense:
http://www.idefense.com/application/poi/display?id=260&type=vulnerabilities

Microsoft:
http://www.microsoft.com/technet/security/bulletin/ms05-033.mspx

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