Case Study: Ashley Madison Hack of 2015

Remember we promised to return to the case of the leak of Ashley Madison? We keep promises!

In 2015, a hacker group broke into Avid Life Media (ALM), the firm that owned Ashley Madison, and stole sensitive user information, including 36 million passwords of users.

The hackers demanded that Ashley Madison permanently shuts down, but they refused, so the hackers published all the data they stole.

Because Ashley Madison passwords were encrypted using a very weak algorithm called MD5, information security researchers who obtained the stolen data cracked (decrypted) passwords with relative ease. The easier the password was, the faster researchers were able to crack it.

Here is a list of the 100 most commonly-used passwords. The most popular password was 123456.