Your average books are mostly, what will sell and not a technical treatise on the subject.

Most of your security is easily upended by simple oversights such as the repair crew that arrives to fix phones or even clean windows. The funniest one I remember is the repair crew was to check electrical outlets and while they were there they installed a power plug wifi hot spot and connected it to the banking LAN. No body gave it a second thought.

http://www.pcmag.com/article2/0,2817,2403675,00.asp

These PWN PLUGs are now much cheaper and look at the thing. Dang small.

Gotcha.
Bob