Comcast warns users when it appears to the company that the users are
downloading copyrighted content. Comcast's alert methodology appears to
resemble a man-in-the-middle attack. The company's practice of injecting
code into unencrypted browser sessions, suggests "that Comcast is using
[deep packet inspection] on subscriber's Internet and/or proxying
subscriber Internet when they want to send messages to subscribers."
http://www.zdnet.com/article/comcast-injects-copyright-warnings-into-your-browser/
