This flaw essentially backdoors every website on the Internet that hosts a PDF. Any website with a PDF can be the target of a hyperlink with a malicious fragment added to it. This flaw is so extremely dangerous because an attacker simply creates a malicious hyperlink to any legitimate PDF on any website and can attack that website.
It gets worse, because there is little a website can do to stop the attack. If a victim clicks on a link like http://bank.com/report.pdf#EVILCode, the #EVILCode fragment is not actually sent to bank.com. Thus bank.com cannot detect if a PDF is being requested to launch an attack, or is being requested for legitimate purposes Short of removing all PDF’s from their site, a company cannot protect itself or it’s users from this technique. This flaw can also be exploited using an HTML iFrame. This means a victim doesn’t have to physically click on a bad link; simply viewing a website could cause a PDF to load and exploit the user.
XSS can be used for various types of attacks, such as phishing, password stealing, self-propagating worms, keystroke logging, and attacking internal corporate networks.
This vulnerability is interesting because it occurs in a browser plugin, making all browser’s that use the plugin vulnerable. It is also interesting because it doesn’t require an attacker to create or upload a malicious file. This attack piggybacks on top of perfectly safe PDFs.
Effected Browser: (all on Windows)
IE6 + Acrobat Reader 7 + XP SP1
IE6 + Acrobat Reader 4 + XP SP2
(possibly) IE 6 on non-XP platforms
Opera 8.5.4 build 770