Well worth a read:
Here's another interesting piece on spying, electronic in this case:
The NYT article states, "Much less is known about another Harris product, the advanced Hailstorm, which is also sold to local police departments. Hailstorm is reportedly capable of implanting malware that can take control of a targeted phone, much like Hacking Team’s R.C.S."
My question: Is it feasible for an IMSI catcher variant like this to implant malware in an intercepted phone during a call?