2017 has been a bad year for data breaches, but what were the worst data breaches of 2017? We have compiled a list of the largest and most serious cyberattacks that came to light this year.

The Worst Data Breaches of 2017

Equifax – 143 Million Records

The Equifax data breach was discovered in September and ranks first in our list of the worst data breaches of 2017, not just for the size of the breach, but also due to the nature of data stolen by the attackers. Equifax reports that the breach impacted as many as 143 million consumers – That’s 44% of the population of the United States.

The data stolen in the attack including highly sensitive information – the types of data cybercriminals seek in order to commit identity theft and fraud. Social Security numbers and driver’s license numbers were stolen along with names, addresses, dates of birth, and credit card numbers. The breach was the result of an unpatched software vulnerability.

Deep Root Analytics – 198 Million Records

The data breach at Deep Root Analytics was massive, involving almost 200 million records. Deep Root Analytics is a marketing firm that was contracted by the Republican National Convention to gather political information on U.S voters.

The data were stored in an Amazon AWS S3 bucket that could be accessed without the need for a password for two weeks before the lack of protection was discovered. During that time, voter records could be accessed, including names, addresses, dates of birth, and phone numbers.

Uber – 57 Million Records

The Uber data breach may not have been the most severe in terms of the types of data exposed, but it certainly ranks as one of the worst data breaches of 2017, affecting some 57 million riders and drivers.

What really makes this one of the worst breaches of 2017 is the discovery that Uber attempted to keep the breach quiet. Uber paid the attacker $100,000 to keep quiet and not publish the data, which included names, addresses, email addresses, and in some cases, driver’s license numbers. The breach occurred in October 2016, but it was not disclosed for more than a year.

Verizon – 14 Million Records

As with many other data breaches in 2017, this security breach was due to an unsecured Amazon AWS S3 bucket that was controlled by NICE systems – A partner of Verizon. It is unclear whether Verizon customer data was stolen, but the records of 14 million customers were exposed. Those records included names, PIN numbers, and phone numbers in the form of logs from Verizon customers that had called its customer service department. Potentially, the information could be used to access customers’ accounts.  The data were stored in an unprotected Amazon AWS S3 bucket

Dun & Bradstreet – 33.7 Million Records

The data analytics firm Dun & Bradstreet created a marketing database containing 52 GB of data, including 33.7 million email addresses and contact information. While Dun & Bradstreet maintains its systems were not compromised, one of the companies that the database was sold to certainly was. The database contained the records of millions of employees of major companies including Wal-Mart and CVS Health, as well as the U.S Postal Service and the Department of Defense.

America’s JobLink – 4.8 Million Records

A misconfigured application was exploited by a hacker to gain access to the records of 4.8 million individuals. The data were maintained by America’s JobLink – a firm that connects employers and job seekers

The breach was detected in March 2017, although an analysis revealed the code error was introduced in October 2016. The hacker exploited the vulnerability in February and had access to the data for a month.

The breach was particularly bad as it involved names, dates of birth and Social Security numbers, placing the breach victims at a high risk of identity theft and fraud. It is unclear whether the hacker managed to steal all 4.8 million records.

Deloitte – 350+ records

In the list of the largest data breaches of 2017, the Deloitte breach would come in very close to the bottom; however, in terms of the potential severity of the breach it ranks near the top. An estimated 350 clients were impacted when a hacker gained access to Deloitte’s email server and email conversations between the firm and its clients. Those clients included government departments – including Homeland Security and the Department of Defense – the National Institutes of Health, FIFA, and the U.S Postal Service.

The breach was discovered this year, although the hackers reportedly had access to its systems for several months. The email server was breached using an admin account, with the breach preventable had two-factor authentication been used.

River City Media – 1.4 Billion Records

A massive illegal spam operation run by River City Media was uncovered this year by security researchers, who discovered more than 1.4 billion records had been left exposed online. An analysis of the data showed there were 393 million unique email addresses in the database, along with names, IP addresses, and real addresses.

The investigation into River City Media revealed the group was sending as many as a billion emails a day, and was masquerading as a legitimate marketing company. The files were exposed due to poor RSync backup practices, which ensured a disaster would not result in data loss, but the firm inadvertently left its data exposed online.

Onliner Spambot – 711 Million Records

Another massive data breach to affect spammers involved the operator of the onliner spambot, which harvested email addresses to send spam emails. A database of some 711 million email addresses was left exposed online after the server on which the data were stored had been left unprotected. It is unknown how many people discovered the database and are now using it to plague those 711 million individuals with email more spam email. The breach was largely limited to email addresses, but in terms of size, it certainly ranks as one of the worst data breaches of 2017.