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Unfortunately my iPhone was stolen yesterday. I did have Find My iPhone enabled, but shortly after the theft my iPhone stopped updating its location. I believe the device was turned off, reset, or had it's SIM card removed.

When finding my iPhone I did notice something interesting though, a MacBook Pro I used in the past but which was handed on to a colleague still shows up in my devices. It, however had a clean install of OS X after the HD was replaced, and is now only linked to my colleague's personal iCloud account, and doesn't even have Find My Mac currently enabled.

Therefor my question is why and how this MacBook Pro is still being tracked in my iCloud account after a complete reset/reinstall? Is it being tracked by MAC address whenever it comes online? Do I have a chance of locating my iPhone in a similar way later on?

I'd really like an authoritative answer on this, as this observed behavior raises additional questions on abuse of Find My Mac after buying a second-hand computer for example, as it seems you need to rely on the seller removing this device from his iCloud account.

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Why didn’t you lock the iPhone the moment it was stolen? If you had locked the iPhone, and a clever thief hadn’t use iTunes to reset it, you could’ve found it. –  duci9y Sep 17 '12 at 8:51
2  
I did lock the iPhone immediately, but that doesn't prevent the thief from shutting it off, doing a factory reset, or removing the SIM. Also the passcode was on for unlocking anyway. –  Gerry Sep 17 '12 at 8:52
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That means a very clever thief. You can still use IMEI tracking, though I don’t know how it’s done in your country. –  duci9y Sep 17 '12 at 8:57

2 Answers 2

up vote 5 down vote accepted
+50

Here's what Apple says:

Because of how Find My Mac works, you must deselect the box next to Find My Mac in the OS X System Preferences > iCloud pane to remove your device from your iCloud Find My iPhone, iPad, iPod Touch, or Mac device list.

One of the ways this persistence is implemented is by writing a Find My Mac token to NVRAM, the persistent memory in Intel Macs. You can see this token by running the following command in a terminal:

nvram -p | grep fmm

On my Mac, the result includes my name, Apple ID, and the name I gave the computer, along with some encoded information that probably includes a key of some sort.

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I've updated my answer after finding it in the NVRAM. –  gabedwrds Sep 20 '12 at 10:14
    
This seems to be the correct explanation. Additionally, we noticed that when my colleague tried to enable FMM for his own account, he was prompted to unlink it from mine first. After he confirmed the data in the NVRAM was replaced with his own account. –  Gerry Sep 20 '12 at 11:09
    
How does it work in OSX ML? I had a MB Pro that was stolen, with password on login and everything.. do I have good chances of getting it back? –  caarlos0 Jun 14 '13 at 18:39

I think it tracks by the "Computer Number" that every macbook has. This "Number" is assigned to your iCloud address on the Apple server, so when you use find my iPhone, it displays your old computer even though it's logged in to your colleges computer.You probably didn't logout of iCloud before clean restoring it. And of course, when you restore the software on the iPhone, it's still assigned to your iCloud account, so yes, I think you should be able to.

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Do you mean the computer's serial number? That's a possibility, but it would be great if we can get a more authoritative answer or reference in here. –  Gerry Sep 20 '12 at 9:29

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