What common technology has been used repeatedly to subvert security measures in high-profile data breaches?

The thumb drive, a recent article on BusinessInsider.com noted, was reportedly used by Edward Snowden to store the information he leaked about NSA. A thumb drive was used to destroy Iranian nuclear facilities. And according to a test conducted by the U.S. Department of Homeland Security, 90 percent of thumb drives that were dropped in the parking lots of government and contractor buildings were plugged into networked computers if the drive had an “official” logo on it.