Rule:

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Sid:
1408

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Summary:
This event is generated when a TCP packet having a large payload was detected. This is a possible indication of an actual or impending denial of service attack against a host running the Microsoft Distributed Transaction Service Coordinator (MSDTC).

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Impact:
Denial of Service (DoS)

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Detailed Information:
MSDTC is used in a distributed or clustered environment for distributed transaction processing on Microsoft operating systems,

A vulnerability exists in the handling of large amounts of data sent to the MSDTC process listening on port 3372. A packet in excess of 1023 bytes will cause the service to become unresponsive, a packet in excess of 2000 bytes may cause the entire system to become unresponsive.

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Affected Systems:
Microsoft IIS 5.0
Microsoft SQL Server 6.5 throught 2000
Microsoft Windows 2000 Advanced Server
Microsoft Windows 2000 Datacenter Server
Microsoft Windows 2000 Server
Microsoft Windows 2000 Professional
 
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Attack Scenarios:
An attacker needs to generate a packet with a payload in excess of 1023 bytes and send it to port 3372 of an affected system.

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Ease of Attack:
Simple.

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False Positives:
Linux FTP servers and clients frequently transfer TCP packets having a payload size larger than 1023 bytes. To distinguish a false positive, determine whether MSDTC is running on the indicated destination source and port.

Peer to Peer transactions may also cause this rule to generate events.

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False Negatives:
None Known

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Corrective Action:
To manage the vulnerability, configure the system not to autmatically start the MSDTC (Source: Security Operations Guide for Windows 2000 Server). Alternatively, configure firewall rules to limit access to the service. To eliminate false positives, revise the Snort rule to specify IP addresses of only those hosts actually running the service.

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Contributors:
Snort documentation contributed by bmccarty@apu.edu
Sourcefire Vulnerability Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>

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Additional References:

Security Tracker:
http://www.securitytracker.com/alerts/2002/Feb/1003415.html

Microsoft:
http://www.microsoft.com/TechNet/security/tools/iis4cl.asp
http://www.microsoft.com/TechNet/archive/transsrv/mtxpg03.asp
http://www.microsoft.com/TechNet/prodtechnol/sql/maintain/featusability/c08ppcsq.asp

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