How Real Spies Operate, or Watch the Donut Not the Hole

“The most vulnerable targets are not computers, but people. Human intelligence gathering is an art. It’s about taking advantage of people’s vulnerabilities, no matter what they are, to get the information.”

And the arsenal to do so is said to be wide-ranging, from “IP intercept, ISMI catchers, dumpster diving, listening devices (bugs) and informants, to students at universities, Chinese businesses and their employees.” more
Michael Biggs and Larry Johnson quoted in the article.