This is a mess you don't want to be a part of: Hacker group AntiSec claims it has gotten a hold of FBI data that contained over 12 million Apple ID numbers linked with other personal information. They have chosen to release just 1 million of them because, as they explain in this post, "a million would be enough," presumably to get the message across. More than just the Apple UDID number, which is a unique, hard to guess code associated with each device (like a serial number), the hack found full names, cell numbers, addresses, and zipcodes tied to the IDs. AntiSec hasn't included that data in the list, only providing the Apple Device UDID, Apple Push Notification Service DevToken, Device Name, and Device Type. Considering all the information at stake -- a leak like this could lead to identity theft -- you might want to check if you're one of the affected devices.
If you happen to know your Apple ID number, which is an alpha-numeric string of 20+ characters, then you can just plug it into this identifier The Next Web put together. (They promise that doesn't store the information, just uses it to check against AntiSec's list.) Since it's likely that you do not know that long complicated code off the top of your head — especially with all those other passwords you have to remember — getting the number involves plugging an iPhone into its home computer and hooking it up to iTunes. Here is a very easy tutorial on how to find it with a few simple steps. In short, plug the phone in, head to "YourPhone" on the iTunes sidebar. Click the summary tab, and there it should say the serial number, click that and then the UDID will show up, as pictured below.
If you happen to be reading this at work right this moment and don't have a way to connect to iTunes, you can use this UDID Sender app or UDID+ app. Both are free. UDID+ takes very little time to retrieve the code, which you can then just send to yourself.
Once you have figured that you have a hacked phone, some questions still remain. First, just because it isn't part of the 1 million, there are still 11 million more that AntiSec hasn't released. Of course, there is a big chance that your device isn't part of this at all, since as of February 2012 Apple has sold over 250 million iPhones and iPads. But there are the bigger questions, like why did the FBI have this information in the first place? What will AntiSec do with it? And, how will Apple react? It's not clear if these numbers are authentic, or just a ruse to get a rise out of us. Neither the FBI nor Apple have commented on the situation yet. So, for now, all we can do to get some peace of mind is check if our phones and tablets are okay.