http://simonwillison.net/2008-07-01T08:58:45+00:00Simon Willison2008-07-01T08:58:45+00:002008-07-01T08:58:45+00:00https://simonwillison.net/2008/Jul/1/evil/#atom-tag

<p><strong><a href="http://radar.oreilly.com/archives/2008/06/partial-same-origin-bypass-wit.html">Evil GIFs: Partial Same Origin Bypass with Hybrid Files</a></strong></p> First there were PNGs that had crossdomain.xml files embedded in them, now there are GIFs that contain Java applets (as JAR files). At this point I’d say don’t even bother trying to validate uploaded files, just make sure they’re served off an entirely different domain instead where XSS doesn’t matter. <p>Tags: <a href="https://simonwillison.net/tags/applets">applets</a>, <a href="https://simonwillison.net/tags/crossdomainxml">crossdomainxml</a>, <a href="https://simonwillison.net/tags/gifs">gifs</a>, <a href="https://simonwillison.net/tags/javaapplets">javaapplets</a>, <a href="https://simonwillison.net/tags/pngs">pngs</a>, <a href="https://simonwillison.net/tags/security">security</a>, <a href="https://simonwillison.net/tags/uploads">uploads</a>, <a href="https://simonwillison.net/tags/validation">validation</a>, <a href="https://simonwillison.net/tags/xss">xss</a></p>