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Category:   Application (Web Server/CGI)  >   Xitami Web Server Vendors:   iMatix
Xitami Web Server Bug in Processing Certain HTTP POST Headers Lets Remote Users Deny Service
SecurityTracker Alert ID:  1008265
SecurityTracker URL:  http://securitytracker.com/id/1008265
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Nov 21 2003
Impact:   Denial of service via network
Exploit Included:  Yes  
Version(s): 2.5 and prior versions
Description:   Tri Huynh from Sentry Union reported a vulnerability in the Xitami web server. A remote user can cause the web service to enter an endless loop.

It is reported that a remote user can send an HTTP POST header line that does not contain a colon character (':') to cause the target web server to enter an endless loop. The web server will then reportedly fail to respond to any requests.

A demonstration exploit header is provided:

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)

The vendor was reportedly notified without response two weeks ago.

Impact:   A remote user can cause the web service to stop processing requests.
Solution:   No solution was available at the time of this entry.
Vendor URL:  www.xitami.com/ (Links to External Site)
Cause:   State error
Underlying OS:  Windows (Any)

Message History:   None.


 Source Message Contents

Subject:  Xitami Denial of Service in Handling malformed request



Xitami Denial of Service in Handling malformed request
=================================================

PROGRAM: Xitami
HOMEPAGE: http://www.xitami.com
VULNERABLE VERSIONS: 2.5 and below


DESCRIPTION
=================================================

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

DETAILS
=================================================

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

CREDITS
=================================================

Discovered by Tri Huynh from Sentry Union


DISLAIMER
=================================================

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
=================================================

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


 
 


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