The Worst Data Breaches of All Time

Credit: Milos Stojanovic/ShutterstockCredit: Milos Stojanovic/Shutterstock

You may remember the 2013 Target Stores data breach that put the credit-card numbers and personal information of millions of people into the hands of cybercriminals. Or you may have been asked to change your Yahoo password in 2016. Both were the results of huge data breaches — yet neither breach was the worst in history.

Here are the 10 biggest and worst verified data breaches that we know of — so far. (We're not including those that haven't been confirmed, such as the Vkontakte breache reported in 2016; had an unknown number of victims, such as the 2014 eBay breach; or didn't involve sensitive data, such as the 2014 JPMorgan Chase breach that exposed only contact information.)

MORE: What to Do After a Data Breach

Yahoo, 2014, disclosed 2016: 500 million accounts compromised

The massive Yahoo breach revealed in late September 2016 not only capped a summer of huge data-breach disclosures, but is the biggest data breach on record.  Yahoo, in the middle of selling itself to Verizon, said "a state-sponsored actor" instead of a regular cybercriminal was likely behind the theft, said to have occurred in late 2014.

Compromised information included real names, email addresses, dates of birth and telephone numbers, helpful to spammers and identity thieves. The good news is that the "vast majority" of the passwords were hashed, or run through a mathematical algorithm, using the so-far-uncrackable Bcrypt method.

MySpace, date unknown, disclosed 2016: 360 million accounts compromised

MySpace dominated social media a decade ago, and it was kind of a chaotic mess. Users quickly found they could hack their own pages to embed any kind of content. Rather than fixing the flaw, MySpace's administrators embraced it, resulting in thousands of loud, ugly personal pages.

So it shouldn't be too surprising that stolen MySpace credentials turned up in the great data-breach wave of 2016, during which a Russian hacker calling himself "Peace" tried to sell off the contents of several old (and hence no longer valuable) data breaches.

What was surprising was the size of the MySpace breach: 360 million account records, including email addresses, usernames and weakly hashed passwords. A list of the most popular passwords in the MySpace breach included references to Michael Jordan and Blink-182, indicating the breach occurred in the mid-2000s.

LinkedIn, 2012, full extent disclosed 2016: 165 million accounts compromised

The world's top business-networking website disclosed its 2012 data breach soon after it happened, but password-reset notifications at the time indicated that only 6.5 million user accounts had been affected. LinkedIn never confirmed the actual number, and four years later, we learned why: A whopping 165 million user accounts had been compromised, including 117 million passwords that had been hashed but not "salted" with random data to make them harder to reverse.

That revelation prompted other services to comb the LinkedIn data and force their own users to change any passwords that matched. (Kudos to Netflix for taking the lead on this one.) Left unanswered is why LinkedIn did not further investigate the original breach, or to inform more than 100 million affected users, in the intervening four years.

Heartland Payment Systems, 2008-2009: 130 million records compromised

In early 2009, this Princeton, New Jersey-based payment processor announced the largest data breach ever to affect an American company. Heartland's breach exposed information from approximately 130 million credit and debit cards to cybercriminals.

Malware planted on Heartland's network recorded card data as it arrived from retailers. Because the company processed payments for more than 250,000 businesses across the country, the impact was huge.

In 2010, Albert Gonzalez, the convicted mastermind behind the Heartland breach (as well as another huge breach), was sentenced to 20 years in prison — the longest sentence ever handed down for computer crime in a U.S. court.

Target Stores, 2013: 110 million records compromised

In December 2013, retail giant Target confirmed that hackers had infected the company's payment-card readers, making off with approximately 40 million credit and debit card numbers that had been used at Target stores in the United States during the 2013 post-Thanksgiving shopping surge.

In January 2014, Target announced that the contact information — full names, addresses, email addresses and telephone numbers — of 70 million customers had also been compromised. Some of those customers probably also had credit-card data compromised in the earlier breach, but it's possible that as many as 110 million people were affected by the Target breaches.

Sony online entertainment services, 2011: 102 million records compromised

In April 2011, attackers whose identities are still unknown targeted the PlayStation Network that links Sony's home gaming consoles, as well as Sony Online Entertainment, which hosts massively multiplayer online PC games, and the Qriocity video- and music-streaming service.

Initially, Sony said that only the personal information of 78 million PlayStation Network users — login credentials, names, addresses, phone numbers and email addresses — had been exposed. But the tally of compromised accounts rose by 24.6 million when investigators discovered the attackers had also penetrated SOE and Qriocity. The credit-card data of approximately 23,400 SOE users in Europe was also stolen.

Following the initial breach disclosure, the PlayStation Network went dark worldwide for more than three weeks. In May 2011, Sony estimated its cleanup costs — which included fighting 65 class-action lawsuits brought against the company — at $171 million. 

Rambler, 2014, disclosed 2016: 98 million accounts compromised

English-language websites weren't the only ones hit by the 2016 disclosures. VKontake, the Facebook of Russia, denied that it had lost 171 million sets of credentials. But Rambler, more or less the Yahoo of Russia, admitted that 98 million of its accounts had been compromised in a breach that the company said occurred in March 2014. (The pay-to-verify breach-data site LeakedSource said the data came from 2012.)

We complain above about weakly hashed passwords, but the Rambler ones weren't hashed at all. They were stored in plaintext, immediately compromising anyone foolish enough to use the same email address or username with the same password on other services. 

National Archive and Records Administration, 2008: 76 million records compromised

Not all data breaches are the result of criminal activity. In late 2008, a hard drive at the National Archive and Records Administration (NARA) stopped working. It held the names, contact information and Social Security numbers of 76 million U.S. military veterans.

Instead of being destroyed on-site, the drive was sent for repair to a government contractor, which determined the drive could not be fixed — so it was sent it out to be scrapped. It is not clear whether the drive was actually destroyed.

Following complaints by an IT manager at NARA, an investigation was launched, and NARA changed its policies to destroy all malfunctioning storage media containing sensitive personal information.

"NARA does not believe that a breach of PII [personally identifiable information] occurred, and therefore does not believe that notification [of the affected veterans] is necessary or appropriate at this time," the agency told Wired News in 2009.

Anthem, 2015: 69 million to 80 million records compromised

In February 2015, Anthem, formerly known as WellPoint and the second-largest health insurer in the U.S., revealed its customer database had been breached. Stolen data included names, addresses, dates of birth, Social Security numbers and employment histories — everything an identity thief might need. As many as 80 million current and former customers were thought to be affected.

Dropbox, 2012, not disclosed until 2016: 68 million accounts compromised

Peace wasn't the only person disclosing old breaches in 2016. A different hacker calling himself "doubleflag" offered the video-news site Vocativ 68 million sets of Dropbox credentials for 2 bitcoin, or about $1,100. Other sources confirmed that the data was real, and Dropbox admitted the data was related to a previously disclosed hacking incident in 2012.

Was Dropbox negligent in not discovering and/or disclosing the extent of the breach earlier? Perhaps. But unlike the LinkedIn breach that had a similar timeline, the passwords in the Dropbox data were strongly protected.

Epsilon, 2011: 60 million to 250 million records compromised

In March 2011, the Texas-based marketing firm Epsilon, which handled email communications for more than 2,500 clients worldwide — including seven Fortune 10 companies — announced that databases pertaining to about 50 Epsilon clients had been stolen.

Email addresses of at least 60 million customers ended up in the hands of cybercriminals, and more than a dozen major retailers, banks, hotels and other companies were affected, including Best Buy, JPMorgan Chase, Capital One Bank and Verizon.

Epsilon could not confirm exactly how many individuals were affected. Conservative estimates put the number of email addresses stolen at 60 million, but according to the Privacy Rights Clearinghouse, a San Diego-based nonprofit advocacy group, the number may have been as high as 250 million. 

Tumblr, 2013, disclosed 2016: 65 million accounts compromised

The image-heavy short-blogging site Tumblr admitted in 2016 that it had been hacked in 2013, following reports that a set of 65 million were circulating online. Peace told VICE Motherboard that the passwords had been strongly hashed and salted, and hence the data set was not worth much. Nonetheless, Tumblr forced its affected users to reset their passwords.

Home Depot, 2014: 56 million payment cards compromised

In September 2014, hardware and building-supplies warehouse retailer Home Depot admitted what had been suspected for weeks. Beginning in April or May of the same year, "carders" had infected its point-of-sale systems at stores in the U.S. and Canada with malware that pretended to be antivirus software, but instead stole customer credit and debit cards. 

The theft may have been the largest haul of payment cards resulting from a direct attack on a retailer, if the lower estimate from the TJX breach (see below) is accepted. But unlike the Target theft less than a year earlier, the Home Depot theft didn't result in customers staying away, nor did it generate quite the same media outcry.

Evernote, 2013: More than 50 million records compromised

In March 2013, users of the note-taking and archiving service Evernote learned that their email addresses, usernames and encrypted passwords had been exposed by a security breach. No financial data was stolen, and the company confirmed that none of the user-generated content on its servers had been compromised.

However, as had been the case for those affected by Epsilon's 2011 breach, Evernote users who had their usernames and email addresses stolen were vulnerable to spam emails and phishing campaigns — some of which pretended to be password-reset emails coming from Evernote itself.

Living Social, 2013: More than 50 million records compromised

In April 2013, Living Social, a daily-deals site partly owned by Amazon, announced that the names, email addresses, birth dates and encrypted passwords of more than 50 million customers worldwide had been stolen by hackers. Twenty million Living Social customers whose information was stored on servers in Asia were not affected.

MORE: 10 Simple Tips to Avoid Identity Theft

TJX Companies Inc., 2006-2007: At least 46 million records compromised

When it was discovered in 2007, the TJX data breach was the biggest theft of consumer data ever in the United States, affecting the parent company of several major retail brands, including Marshalls, T.J. Maxx and HomeGoods. At least 45.6 million credit and debit card numbers were stolen over an 18-month period, but some estimates put the number at closer to 90 million.

About 450,000 TJX customers also had their personally identifiable information stolen, including driver's license numbers. The breach ultimately cost the Framingham, Massachusetts-based company $256 million.

The TJX hackers included Albert Gonzalez, who was cooperating with law-enforcement investigations into earlier data thefts when he took part in both the TJX breach and the even larger Heartland Payment Systems attack two years later.

Honorable mention: Sony Pictures Entertainment, 2014: Company's inner workings completely exposed

On Nov. 24, 2014, staffers at Sony Pictures Entertainment, the movie and television production division of Sony, had their computer screens hijacked by a grinning skull. A group calling itself Guardians of Peace said it had taken over the corporate network and would release detailed company information online if unspecified demands weren't met.

Within days, gigabytes of internal Sony Pictures data appeared on file-sharing sites, including Social Security numbers and scanned passports belonging to actors and executives, internal passwords, unpublished scripts, marketing plans, financial and legal information and even four entire unreleased Sony movies.

The company's 6,800 employees, plus an estimated 40,000 other individuals the company had paid over previous years, were placed at dire risk of identity theft, and rival Hollywood studios got a detailed blueprint of Sony Pictures' accounts, future plans and internal workings.

Some rumors blamed North Korea, others disgruntled insiders. Whatever the cause, the incident threatened the very survival of Sony Pictures Entertainment as a company and may be the most damaging corporate data breach ever.

Follow Elizabeth Palermo on Twitter @techEpalermo, Facebook & Google+. Follow Tom's Guide @tomsguide and Facebook & Google+.

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