Rule:  

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Sid:
3003

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Summary:
This event is generated when an attempt is made to exploit a known 
vulnerability in the Microsoft implementation of the ASN.1 Library.

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Impact:
Serious. Execution of arbitrary code, DoS.

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Detailed Information:
A buffer overflow condition exists in the Microsoft implementation of
the ASN.1 Library. It may be possible for an attacker to exploit this
condition by sending specially crafted authentication packets to a host
running a vulnerable operating system.

When the taget system decodes the ASN.1 data, exploit code may be included 
in the data that may be excuted on the host with system level privileges. 
Alternatively, the malformed data may cause the service to become 
unresponsive thus causing the DoS condition to occur.

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Affected Systems:
	Microsoft Windows NT
	Microsoft Windows NT Terminal Server Edition
	Microsoft Windows 2000
	Microsoft Windows XP
	Microsoft Windows 2003

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Ease of Attack:
Simple. Exploit code exists.

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False Positives:
This rule is known to false positive on Active Directory and Domain Controller
traffic.  If this event is being generated on traffic to a Domain Controller or
Active Directory server it is recommended that this rule be disabled or
suppressed for that host.

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False Negatives:
None known.

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Corrective Action:
Apply the appropriate vendor supplied patches.

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Contributors:
Sourcefire Vulnerability Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

Microsoft:
http://www.microsoft.com/security/encyclopedia/details.aspx?name=win32/rbot

US-CERT
http://www.us-cert.gov/cas/techalerts/TA04-041A.html

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