How did we destroy Iranian nuclear facilities? With a thumb drive. And how did Snowden allegedly smuggle out the blueprints to the NSA? With a thumb drive.
No, it wasn't by some ultra secretive means of super-complex cyber code writing and cloud encryption by which good ol' Eddy breached America's security in arguably the most secure compound on the planet — nope — he simply walked in with a thumb drive, downloaded the NSA, and walked out.
For the rest of the story: http://www.businessinsider.com/the-biggest-threat-to-national-security-is-the-thumb-drive-2013-7