Shortly after Carnegie Mellon University professor Lorrie Cranor became chief technologist at the Federal Trade Commission in January, she was surprised by an official agency tweet that echoed some oft-repeated security advice. It read: "Encourage your loved ones to change passwords often, making them long, strong, and unique." Cranor wasted no time challenging it.
The reasoning behind the advice is that an organization's network may have attackers inside who have yet to be discovered. Frequent password changes lock them out. But to a university professor who focuses on security, Cranor found the advice problematic for a couple of reasons. For one, a growing body of research suggests that frequent password changes make security worse. As if repeating advice that's based more on superstition than hard data wasn't bad enough, the tweet was even more annoying because all six of the government passwords she used had to be changed every 60 days.
"I saw this tweet and I said, 'Why is it that the FTC is going around telling everyone to change their passwords?'" she said during a keynote speech at the BSides security conference in Las Vegas. "I went to the social media people and asked them that and they said, 'Well, it must be good advice because at the FTC we change our passwords every 60 days."