Analyzing Major Password Breaches

The LinkedIn breach of 2012 serves as a watershed moment in password security awareness. Hackers stole 117 million user credentials, but the real shock came from LinkedIn's storage method—SHA-1 hashing without salts. This outdated approach allowed security researchers to crack millions of passwords within days, exposing the prevalence of weak passwords like "123456" and "linkedin". The breach highlighted how even technology companies could fail at basic password security and accelerated industry-wide adoption of modern hashing algorithms.

Yahoo's series of breaches between 2013 and 2014 affected all 3 billion user accounts, making it the largest known password breach in history. The company used MD5 hashing, an algorithm considered cryptographically broken since the 1990s. The breach's massive scale demonstrated how legacy systems and technical debt create long-term security vulnerabilities. Yahoo's market value plummeted, and Verizon reduced its acquisition price by $350 million, illustrating the severe business consequences of inadequate password security.

The RockYou breach of 2009, while smaller in scale at 32 million accounts, shocked the security community by storing passwords in plaintext. This inexcusable practice allowed attackers immediate access to all user passwords without any cracking required. Analysis of the exposed passwords revealed disturbing patterns: "123456" was used by 290,731 users, and the top 5,000 passwords covered 20% of all users. RockYou's breach became a cautionary tale and its password list continues to be used for security research and dictionary attacks.