Rule:

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Sid:
3626

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Summary:
This event is generated when an attempt is made to cause a denial of
service against a host by causing it to send unnesessarily small packets.

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Impact:
A successful attack can cause a denial of service by convincing a host
that it must send small packets to destination hosts.

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Detailed Information:
The ICMP path MTU message informs a host that the packet size it has
sent must be fragmented and will be dropped unless it is reduced to the
designated MTU. An attacker can send a spoofed ICMP path MTU message to
a host causing it to send very small packets. The patch for this
vulnerability causes the host to ignore any ICMP path MTU messages with
a suggested MTU size less than 576.

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Affected Systems:
	Windows 98, 98 SE, ME
	Windows 2000
	Windows XP Service Pack 1
	Windows XP Service Pack 2
	Windows Server 2003

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Attack Scenarios:
An attacker can send spoofed ICMP path MTU messages to a host that
contain unreasonably small MTU's to use when sending packets.

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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

Other:
http://www.microsoft.com/technet/security/bulletin/MS05-019.mspx
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