Password Reuse: Don’t Mix Business With Personal

You join a social network, file-sharing service, or other online service, and of course get asked for a password. You’re busy, so you quickly type in one of your existing passwords, maybe even planning to change it later. The risk of a data breach at your company just increased dramatically.

In 2012, criminals managed to steal 112 million login credentials from LinkedIn. The account of someone who worked at Dropbox was one of those stolen, and that person had reused a password from a corporate account as the LinkedIn password. Using that info, criminals then stole over 68 million login credentials from Dropbox. The effort required for cybercriminals to pivot from a personal data breach to an attack against an organization is trivial when personal and business passwords are reused.

We did an internal survey asking employees about their password behaviors. Just over 16% said they use the same or similar passwords for both personal and corporate accounts. While this number may not seem significant, a closer look at the number involved paints a different picture.

If 16% of people reusing passwords is the average for the workforce, there will be 10.9 million examples of password reuse out of 68 million stolen credentials. As an attacker, I would start with people who have used their corporate email address as their username to identify potential targets. Then I might google some of the other names to see if I can determine where they work. For example, if I find [email protected], it is easy to presume that I work for Intel, and that the corporate email address schema is [email protected]. I would then go to other popular web services and file-sharing sites (Office 365, Google Drive, Box, etc.) and attempt to gain access. Even if I only get hits on 5% of the 11.5 million who reused their passwords, that is almost 600,000 accounts I potentially now have access to. 

We asked a few more questions in our survey. Almost 25% of respondents reported that they had been notified of a breach on a personal account in the last 12 months, meaning that 4% of our surveyed group who reused passwords had also been breached. If that applies to the entire Intel Security workforce, that is 4,000 accounts throughout the company that offer potential entry points. I don’t like those odds.

Of course, part of the challenge with passwords is remembering them. To help make this easier, more than half of those surveyed rely on a set of less than 10 passwords across the myriad sites they use. Password managers have been developed to address this problem, but unfortunately almost 65% of the group say they’re not using a password manager. The good news is that almost 60% of them use multifactor authentication for some of their personal accounts -- most likely banking- and healthcare-related ones -- which provides extra protection in the event their credentials are stolen.

Passwords continue to be the weakest link in cybersecurity, and reusing passwords makes attacks much easier for cybercriminals. Employee education, password managers, and multifactor authentication are the top three tools that can be used to reduce the risk of a personal breach becoming a corporate security event.