Last month the dating site eHarmony suffered a data breach in which more than 1.5 million eHarmony password hashes were stolen and later dumped online by the hacker gang called Doomsday Preppers. The crypto-based "hashing" process is supposed to conceal stored passwords, but Trustwave's SpiderLabs division says eHarmony could have done this process a lot better because it only took 72 hours to crack about 80 percent of 1.5 million eHarmony hashed passwords that were dumped.

Cracking the dumped eHarmony passwords wasn't too hard, says Mike Kelly, security analyst at SpiderLabs, which used tools such as oclHashcat and John the Ripper. In fact, he says it was one of the "easiest" challenges he ever faced. There are many reasons why this is so, starting with the fact the cracked passwords may have been "hashed," but they weren't "salted," which he says "would drastically increase the time it would take to crack them."

BACKGROUND: Dating site eHarmony confirms password breach

He points out that hashing the passwords with a crypto algorithm is a good start to scramble the password, but by adding the "salt" of a random string in the process, the "salted hash" is far stronger protection. eHarmony was also using the MD5 format, which is considered somewhat weak by cryptographers today, Kelly adds.

Other aspects that made the eHarmony password crack so easy is that "they were storing the passwords in case-insensitive mode," says Kelly. "They eliminated the upper-case letters," adding that this drastically reduced the time to crack them. SpiderLabs acknowledges the possibility that the attackers who hit eHarmony may have changed some passwords since no single password was found more than three times. The most popular length of password was seven characters, SpiderLabs said.

The passwords used by the eHarmony site visitors shows that names of sports teams, dogs, states and masculine and feminine names formed the foundation of many of the passwords. The most popular hockey team was the Minnesota Wild, and the most popular football team was the St. Louis Rams.

Ellen Messmer is senior editor at Network World, an IDG publication and website, where she covers news and technology trends related to information security.

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This story, "Password Protection 101: Lessons From the eHarmony Data Breach " was originally published by Network World .