Rule: 

--
Sid: 
119-9

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Summary: 
This event is generated when the pre-processor http_inspect
detects network traffic that may constitute an attack.

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Impact: 
Unknown. This may be an attempt to obfuscate an attack or an attempt to
evade an IDS.

--
Detailed Information:
This event is generated when the pre-processor http_inspect detects a
"\" character being used where a "/" is normally expected in a web
request.

This may be an attempt to obfuscate an attack or an attempt to evade an
IDS.

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Affected Systems:
	Microsoft IIS web servers.

--
Attack Scenarios: 
An attacker merely needs to use a "\" character instead of a "/"' in a
web request.

-- 
Ease of Attack: 
Simple.

-- 
False Positives:
None Known.

--
False Negatives:
None Known.

-- 

Corrective Action:
Check the target host for signs of compromise.

Apply any appropriate vendor supplied patches.

--
Contributors:
Daniel Roelker <droelker@sourcefire.com> 
Sourcefire Vulnerability Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

-- 
Additional References:

HTTP IDS Evasions Revisited - Daniel Roelker
http://docs.idsresearch.org/http_ids_evasions.pdf

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