[Snort-sigs] Apache Proxy

Chris Kronberg smil at ...1754...
Fri Jan 14 07:15:07 EST 2005


   Hiho,


> Actually, these rules are never going to fire -- at least not under normal 
> circumstances where clients are following RFC 2616 
> (http://www.faqs.org/rfcs/rfc2616.html). GET requests look like this when 
> they come across the wire:
>
> GET /path/to/file.html HTTP/1.1
>
> Clients never need to transmit the http://<host> portion of a URL: http:// is 
> obvious because the packet is being received by an HTTP server, and <host> is 
> either implied from wherever the packet is being sent, or stated explicitly 
> with a directive of
>
> Host: www.example.com
>
> somewhere following the GET request (most likely immediately after it).

   That true for all normal requests. Yet I believe that Adam wants
   to trigger for the following attempts:

   GET http://www.ebay.com/ HTTP/1.1" 200 2986

   I see hat every now an then in the logfiles of the servers I manage.
   Don't be confused by the "200" - its the homepage that is delivered.

> Even if they did fire, though, I'm a bit confused as to how these rules 
> differentiate between a misconfigured proxy server and a standard web server.

   In the example above you get www.ebay.com instead of the original
   requested webserver if that webserver is indeed misconfigured.
   A nice way to cirumvent URL Scanners.

> In theory, these would fire on every single request that comes into one of 
> your web servers -- and if you run even a moderately busy server, you're

   Not even in theory. You wrote yourself that a legitimate request is
   GET /path/to/file.html
   There is only a small number of "GET http://blabla..." requests. None
   of them was ever legitimate. Maybe other people have different
   experiences?

   Cheers,


                                                         Chris Kronberg.




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