Following the hack of the global intelligence firm Stratfor, hackers published the stolen password file containing the usernames and hashes for more than 860,000 accounts. An effort to use typical password breaking techniques on the file yielded quick results: About 1 in every 10 accounts had a trivial password.

While it's unknown how many account holders reused their passwords, many subscribers used e-mail addresses of their employer, suggesting the possibility that they reused their passwords as well. While real-world research is scarce, what little there is suggests that reuse is rampant. Following the breach of Sony's online sites last year, for example, an analysis connected a small subset of users to those whose passwords were leaked in another breach. Two-thirds reused their passwords.

For companies, password reuse weakens security and can cause a company to rely on the security of third-party firms whose security is questionable. While companies can attempt to cordon off their employees' work and personal lives, workers can inadvertently reconnect the two, said Sam Curry, chief technology officer for security giant RSA's identity and data protection business unit.

"The average person probably has one or two phones, and they probably have any number of consumer services they subscribe to and two or three machines they interact with," says Sam Curry, chief technology officer for RSA's identity and data protection business unit. "If the password is the same everywhere, then there are literally dozens or hundreds of places where their passwords might be cached or the hash of it might be cached."

While companies can set policy and educate their employees to use good passwords and not reuse the secret codes--especially between business and personal sites--information security specialists should seek other solutions, says Mark Joynes, director of product management for Entrust.

"Enterprises that are taking the matter of security seriously should not be relying on password mechanisms," says Joynes. "As a function of human nature, users will reuse passwords irrespective of the relative risk of the application."

Consider these five steps to mitigate the risk.

It's no longer a matter of if you get hacked, but when. In this special retrospective of news coverage, Monitoring Tools And Logs Make All The Difference, Dark Reading takes a look at ways to measure your security posture and the challenges that lie ahead with the emerging threat landscape. (Free registration required.)