The hacking tools not only focus on PCs but also on smartphone and can be installed remotely using a document or link that loads the spyware when the suspect clicks or views it. In some cases though, the FBI secretly gains physical access to the suspects' PCs and installs malware using a flash drive. Among other things, these tools enable the FBI to remotely activate microphones and cameras in PCs and devices running Google's Android operating system, as well as to track communications and access files.
The FBI "hires people who have hacking skill, and they purchase tools that are capable of doing these things," said a former official in the agency's cyber division. The tools are used when other surveillance methods won't work: "When you do, it's because you don't have any other choice," the official said.Further details can be read at WSJ.
Surveillance technologies are coming under increased scrutiny after disclosures about data collection by the National Security Agency. The NSA gathers bulk data on millions of Americans, but former U.S. officials say law-enforcement hacking is targeted at very specific cases and used sparingly.