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List:       vulndiscuss
Subject:    [VulnDiscuss] Re: Http Response Splitting Vulnerability In PHP-NUKE 7.6 and below
From:       Paul Laudanski <zx () castlecops ! com>
Date:       2005-04-15 23:58:01
Message-ID: Pine.LNX.4.44.0504151948510.3279-100000 () bugsbunny ! castlecops ! com
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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@www.securityfocus.com>
> 
> "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));
> $location = str_replace('&amp;', '&', htmlspecialchars($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.

-- 
Sincerely,

Paul Laudanski .. Computer Cops, LLC.
Microsoft MVP Windows-Security 2005
CastleCops(SM)... http://castlecops.com
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