Xitami Denial of Service in Handling malformed request
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PROGRAM: Xitami
HOMEPAGE: http://www.xitami.com
VULNERABLE VERSIONS: 2.5 and below


DESCRIPTION
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LiteServe is a very powerful, full-featured, open-sourced Web server.
and the flagship of iMatix. This is a great free product.

DETAILS
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Xitami has a logical error in the way it handles POST request that can be
used to perform a Denial-of-service attack. An Request like this will
make the server won't response to any other requests although it is
still listen to port 80
POST /forum/index.php HTTP/1.1
Referer: Sentryunion
Accept-Encoding: None
User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)
Content-Length: 10
(long string here)
0x0D 0x0A
(another long string here)
Xitami is a very good server. However the code to handle parsing the HTTP
header doesn't have a good logic:

while(header && *header && *header != '\r')
{
header_name = header
if((header_value=strchr(header_name, ":")) != NULL)
{ ... header++;}
}
So if inside the request HTTP header there is no ":" charater. It will make
the
while loop runs forever = Denial of Service.

WORKAROUND
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Use URL filter to filter all the bad request. Vendor doesn't response
after 2 weeks !

CREDITS
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Discovered by Tri Huynh from Sentry Union


DISLAIMER
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The information within this paper may change without notice. Use of
this information constitutes acceptance for use in an AS IS condition.
There are NO warranties with regard to this information. In no event
shall the author be liable for any damages whatsoever arising out of
or in connection with the use or spread of this information. Any use
of this information is at the user's own risk.


FEEDBACK
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Please send suggestions, updates, and comments to: trihuynh@zeeup.com