Rule:
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Sid:
1129
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Summary:
This event is generated when an attempt is made to access the file 
".htaccess" from a web server.

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Impact:
If this request is successful, it could provide an attacker with 
valuable information needed to compromise the website.

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Detailed Information:
Most UNIX based web servers, such as Apache and Netscape Enterprise 
Server, use ".htaccess" files to customize security settings on a 
per-directory level. These files can specify things like what users 
have access to what resources, hosts that are allowed or denied, and 
what type of authentication system to use.   This type of data would be 
most useful for carrying out an attack on the site.   Fortunately, all 
modern web servers deny client access to these files by default.

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Affected Systems:
Any system that uses ".htaccess" files and which have misconfigured the 
server to allow client access to them.

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Attack Scenarios:
This is an information gathering operation which could facilitate an 
attack.

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Ease of Attack:
It is simple to send a request for this file, but the request would only
be successful if the file exists and the server allows access to it.

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False Positives:
While unlikely, certain web servers that are set up to host multiple 
users' sites may allow access to this file by the site owners.

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False Negatives:
None known.

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Corrective Action:
First determine if the attack is successful by requesting the file 
yourself. If the request is granted, ensure that your web server is 
configured to deny access to all files that begin with ".ht".

The default configuration for the Apache HTTP Server should include the 
following section to prevent access to .ht files:

<Files ~ "^\.ht">
    Order allow,deny
    Deny from all
</Files>

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Contributors:
Sourcefire Research Team
Brian Caswell <bmc@sourcefire.com>
Nigel Houghton <nigel.houghton@sourcefire.com>
Snort documentation contributed by Kevin Peuhkurinen
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Additional References:

Webdeveloper.com
http://www.webdeveloper.com/servers/servers_htaccess_magic.html

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