As per the eurogamer report, Xbox 360 owners account is hacked in order to buy FIFA ultimate Team content packs. 

One of victim Speedjack reported to Eurogamer first about the compromise , who on 11th October found his gamertag had been "recovered" to someone else's machine.

"I then find out that I've had 5000 then 500 MS points bought on my credit card. Better yet, all the points including the 120 I had already on my account are gone... all spent on FIFA 12 content packs yesterday afternoon while I was at work.

"Not only that, but my account now has 35 FIFA 12 achievement points on it!!! Never played the game in my life - hate football."  Speedjack spoke to Microsoft support, which suggested there exists an issue with EA's servers that leaves XBL accounts vulnerable.

There is also a similar report on forum Facepunch, and multiple users' reports on the Xbox.com forum.

In order to Investigate complaints ,Microsoft support freezed compromised accounts up to 30 days.