Live ID exploit
On the 17th june 2007, Erik Duindam, discovered that if you
- Create a Live ID using your e-mail address
- Modify your e-mail address before activating your account
- Then activate the account
Well, in this way you can create fake, authenticated, Live IDs. Actually you can specify an existing e-mail address, for example of someone you want to impersonate.
Source: Wikipedia