Your corporate firewall. That invulnerable bastion that lets you fearlessly run less-than-secure internal tools like a CRM, a Finance portal. But, is it really invulnerable? Or is it a paper wall at best? We look at how Cross-Site-Scripting vulnerabilities, known session ID cookies or access tokens can allow content from the world to pierce it as if it were not there. We do this using the weakest link: you.