Re: Preventing cross site scripting

The most elegant way to control html input would be to parse it to a DOM tree and control it from there; I'm widely using Tidy to `correct' the input to XHTML, then by a simple XSL transformation I can filter/alter whatever elements I need.

You want to drop the `object' element, just write `<xsl:template match="object" />', you want to ignore it (preserve the content it wraps) just write `<xsl:template match="object"><xsl:apply-templates
/></xsl:template>', you want to copy everything else:

<xsl:template match="*|@*|text()|comment()">

    <xsl:copy>

        <xsl:apply-templates select="*|@*|text()|comment()" />     </xsl:copy>
</xsl:template>

I consider filtering html as it was a mere string (i.e. using regexp or simple replace methods) pretty uncertain in results and not quite programming :) -- it's a language, it has a grammar, then use a parser.

Cheers,

-- 
Laurian Gridinoc
Chief Developer
GRAPEFRUIT DESIGN

tel/fax: +40.232.233068
tel/fax: +1.646.349.2916
mobile: +40.745.304379
e-mail: laur@gd.ro
www.grapefruitdesign.com
www.gd.ro

Do you need help?

In addition to our free technical library, Pantek provides professional IT services to companies who utilize Open Source software: Learn more about Pantek's Technical Support offerings Place an order for 24/7/365 Technical Support here Learn more about Pantek, who we are, and what we do Chat with a Live Operator Related securityfocus.com Links bugtraq certification focus-bsd focus-ids focus-ih focus-linux focus-ms focus-sun focus-unix-other focus-virus forensics incidents libnet linux-secnews ms-secnews pen-test secpapers secprog sectools secureshell security-basics securityjobs sf-news vuln-dev webappsec Request more information about Pantek