Full Disclosure mailing list archives

Re: Apache/PHP REQUEST_METHOD XSS Vulnerability


From: "Michal Majchrowicz" <m.majchrowicz () gmail com>
Date: Tue, 24 Apr 2007 00:19:18 +0200

Hi.
I am not a flash expert but you can find many interesting things about
flash and playing with http headers. For instance the case of Expect
XSS Vulnerability. I don't know any way to exploit but If I don't know
it doesn't mean there isn't one :)
Regards Michal.

On 4/24/07, InSiStKool <insistkool () gmail com> wrote:
H Michael,
This is interesting. I do able to see the output after injecting the xss
statement, but I don't see how is possible to be used. Further,
GET<script>alert(document.coookie);</script> /test.php HTTP/1.0
I only know we can use nc or telnet to execute the above statement, how can
you execute it with a browser like ff or ie?

You mentioned "some flash might help", can you give me an example?

Thanks
insistkool


On 4/23/07, Michal Majchrowicz <m.majchrowicz () gmail com> wrote:

There exist a flaw in a way how Apache and php combination handle the
$_SERVER array.
If the programmer writes scrip like this:
<?php
              echo $_SERVER['REQUEST_METHOD'];
?>
He will assume that REQUEST_METHOD can only by: GET,POST,OPTIONS,TRACE
and all that stuff. However this is not true, since Apache accepts
requests that look like this:
GET<script>alert(document.coookie);</script> /test.php HTTP/1.0
And the output for this would be:
GET<script>alert(document.coookie);</script>
Of course it is hard to exploit (I think some Flash might help ;)) and
I don't know if it is exploitable at all. But programmers should be
warned about this behaviour. You can't trust any  variable in the
$_SERVER table!
Regards Michal Majchrowicz.

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