Technically http response splitting occurs when a web application fails to
reject illegal input such as the CR and LF characters. PHP-Nuke's
mainfile.php has had the following function in it:
function removecrlf($str) {
return strtr($str, "\015\012", ' ');
}
So the power is there to stop it, but it isn't being used.
It should be called more frequently on user input validation. However, a
one stop shop would be to install mod_security with the appropriate
filters. It won't just protect a webapp like php-nuke or postnuke, it'll
protect all the pages accessible via Apache.
However, $forwarder should only accept URLs, and nothing more in this
example. As such, there ought to be a whitelist of characters that are
approved for input specific to URLs.
But when it comes to CRLFs, I can't see anything at the moment why they
ought to be whitelisted.
On 15 Apr 2005, JeiAr wrote:
> In-Reply-To: <20050416033018.9721.qmail@xxxxxxxxxxxxxxxxxxxxx>
>
> "Possible Fixes: The usage of htmlspeacialchars(), mysql_escape_string(), mysql_real_escape_string()
> and other functions for input validation before passing user input
> to the mysql database, or before echoing data on the screen, would solve these
> problems."
>
> The htmlspecialchars() would most definately keep the html code from being rendered, but would it really fix http response splitting?
>
> Maybe something like this would work better?
>
> $location = str_replace('\n', '', urldecode($location));
> $location = str_replace('\r', '', urldecode($location));
> $location = str_replace('&', '&', htmlspecialchars($location));
>
> James
>
>
> >Dcrab 's Security Advisory
> >[Hsc Security Group] http://www.hackerscenter.com/
> >[dP Security] http://digitalparadox.org/
> >
> >Get Dcrab's Services to audit your Web servers, scripts, networks, etc. Learn more at http://www.digitalparadox.org/services.ah
> >
> >Severity: High
> >Title: Http Response Splitting Vulnerability In PHP-NUKE 7.6 and below
> >Date: 15/04/2005
> >
> >Vendor: Php-Nuke
> >Vendor Website: http://www.phpnuke.org
> >Summary: There are, http response splitting vulnerability in php-nuke 7.6 and below.
--
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Microsoft MVP Windows-Security 2005
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