This advice is wrong. Try turning off an older feature phone's regular operating system, and then plugging it in to charge. Many of them will immediately come alive with a "charging" indicator on the screen, even when supposedly powered off. This pre-boot mode is perfectly capable of turning on the mic and recording what's going on.
Combine this kind of thing with a database of phone remote expoits and it's easy for the NSA to "upgrade" your phone's software and turn it into a bug. This is what Snowden means when he talks about "poor endpoint security." It doesn't matter how secure your fancy encryption applications are when the phone itself can easily be hacked.
Sometimes they don't even have to remotely push software. There was a recent scandal about Carrier IQ, a system on smartphones (Android players and iPhone) that by default was recording every tap, every virtual key pressed, every incoming/outgoing SMS, and more. Anyone with the device connected to a PC could take the forensic log off the phone and see basically everything, even in the past. With per IP logging and billing on mobile plans, as Snowden's Verizon leaks showed, the NSA can just have your phone upload that log anytime they like, without a trace on your bill or data usage.
Combine this kind of thing with a database of phone remote expoits and it's easy for the NSA to "upgrade" your phone's software and turn it into a bug. This is what Snowden means when he talks about "poor endpoint security." It doesn't matter how secure your fancy encryption applications are when the phone itself can easily be hacked.
Sometimes they don't even have to remotely push software. There was a recent scandal about Carrier IQ, a system on smartphones (Android players and iPhone) that by default was recording every tap, every virtual key pressed, every incoming/outgoing SMS, and more. Anyone with the device connected to a PC could take the forensic log off the phone and see basically everything, even in the past. With per IP logging and billing on mobile plans, as Snowden's Verizon leaks showed, the NSA can just have your phone upload that log anytime they like, without a trace on your bill or data usage.
It's a scary world of surveillance in 2013.