UPDATE: On the official Call of Duty MW3 forums, Infinity Ward Dev G IH A IN ID II posted a quick update to this situation. He stated:
“A modding group created a viral mod, which we prevented from spreading within twelve hours yesterday. Sadly, in ‘protest’ at our ability to disable this they are now inviting player’s to private matches where they reset their stats. We have a fix for this in the works and are backing up player’s stats so that we can restore them if needed next week. In the meantime avoid friend invites from ANYONE not on your friend list.”
BREAKING NEWS: We believe this was just confirmed by Infinity Ward’s Fourzerotwo just minutes ago.. Still trying to get clarification, we’ll keep you posted.