Which brings me back to a question I had. I should have just tested this by now but havn't had time. If you have lastpass installed on one computer and want to start using the same account on another. Does it load the passwords to the new computer when you validate there? (If so then the backdoor thing could work.) But what I was under the impression of, is if you want to use an account on another computer you had to export the saved passwords and physically place them on the new computer?? If that's the case it would have done our alleged hacker no good to just know the password..
You just need to install Lastpass on your new computer and enter your password. It will download your passwords from the encrypted server.