Rule: 

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Sid: 
100000133

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Summary: 
This event is generated when an attempt is made to cause a denial of service 
against the Xeneo web server by sending it a request with an overly large 
number of "?" characters.

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Impact: 
A denial of service will occur, and it may be possible to execute arbitrary 
code with the privileges of the user running the web server.

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Detailed Information:
The denial of service is triggered when a GET request is made with more than 
4096 "?" characters. The rule actually looks for 250 consecutive "?" 
characters, as even that should never occur, and looking for a smaller number 
increases the rule's performance.

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Affected Systems:
Northern Solutions Xeneo Web Server 2.2.10

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Attack Scenarios: 
This vulnerability may be exploited with a web browser or an automated script.

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Ease of Attack: 
Simple, as a web browser can be used.

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False Positives:
If a valid request contains more than 250 and less than 4096 consecutive "?" 
characters, a false positive will be generated.

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False Negatives:
None Known

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Corrective Action: 
Currently, no patches or upgrades are available from the vendor, and no 
workarounds are known.

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Contributors: 
Alex Kirk <alex.kirk@sourcefire.com>

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Additional References:

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