Rule:  

Sid:
1021

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Summary:
This event is generated when an attempt is made to retrieve file
contents by exploiting a vulnerability in Microsoft Internet 
Information Server (IIS) ISAPI component.

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Impact:
Information Disclosure.

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Detailed Information:
Default installations of IIS 4.0 and IIS 5.0 contain a vulnerability in
ISM.DLL that can allow an attacker to retrieve the contents of
files on the system.  This could be used to retrieve web application
source code or the contents of other sensitive files.

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Affected Systems:
	Microsoft IIS 4.0 and 5.0
	Multiple vendor implementations of IIS.

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Attack Scenarios:
The attacker sends a URL containing the file to be retrieved (without the
extension), followed by approximately 230 "%20" (ascii space) characters 
followed by ".htr".

Note: This attempt can only be performed once. The server must be
restarted to make another sucessful request.

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Ease of Attack:
Simple. No exploit software required.

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False Positives:
None Known

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False Negatives:
None known

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Corrective Action:
Check server logs for signs of compromise.

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Contributors:
Original rule writer unknown
Original document author unkown
Sourcefire Vulnerability Research Team
Nigel Houghton <nigel.houghton@sourcefire.com>

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References:

CVE:   CAN-2000-0457
Bugtraq:  BID 1193

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