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Ask Slashdot: How To Stay Ahead of Phone Tracking ?
An anonymous reader writes "In the last few years there has been a significant upsurge in subverting the cellular network for law enforcement purposes. Besides old school tapping, phones are have become the ideal informant: they can report a fairly accurate location and can be remotely turned into covert listening devices. This is often done without a warrant. How can I default the RF transmitter to off, be notified when the network is paging my IMSI and manually re-enable it (or not) if I opt to acknowledge the incoming call or SMS? How do I prevent GPS data from ever being gathered or sent ?"
Well, we have known for quite some time that is is not just possible to use your dumb phone as a roving bug while it is turned off, but that it has actually been done.
http://news.cnet.com/2100-1029-6140191.html
So even though you sound a bit (albeit justifiably) paranoid, you might not be paranoid enough.
That switch that you use to turn your phone off is nothing but a sensor switch. Its not a physical on/off switch disconnecting the battery from the phone circuits. When you press it, the OS on the phone is programmed to start shutting down certain circuits within the phone. It keeps other circuits powered up so that it can sense that same switch to bring the phone back up to its normal powered state.
That being said, someone can reprogram the phone to 'look like' its powered off. It can still be recording audio/video to the local memory, or whatever it wants to, and even use the transmitter periodically without being noticed by the owner.
The phone can be reprogrammed fairly easily by someone who gains control of the device. How easy is that? I've seen a demonstration by an expert that took all but 15 seconds to have root on a popular phone. All that was needed was an IP address of the data connection for the handset. In an instant they had the equivalent of ftp and could have done anything on that phone, including staging a boot loader/update waiting for the next time you cycled the phone's OS.
For someone who has the power of the courts behind them, they can easily have the phone company push an update out to the phone to do the same thing. Nobody needs to hack your phone, and they can then completely control the outward appearance of the devise without you knowing anything about it.
Other than having an RF monitor next to the phone you likely won't be able to detect it. A small RF monitor can be purchased and hacked to add a audible warning if the phone becomes active, if you are the tin foil hat type. Otherwise, if the phone is active and uses the network the battery will get slightly warm, even when turned off, so you might be able to tell that way. A cheap way to tell is a liquid crystal temperature strip adhered to the outside case where the battery compartment is. This is also a help if your phone has a battery drainage problem with certain apps, because it will tell you when the battery is being drained, and how quickly, for whatever reason.