By Taylor Armerding

CSO | SEP 7, 2017 2:56 PM PT

Security practitioners weigh in on the 16 worst data breaches in recent memory.

 

Data breaches happen daily, in too many places at once to keep count. But what constitutes a huge breach versus a small one? CSO compiled a list of 16 of the biggest or most significant breaches of the 21^st century.

This list is based not necessarily on the number of records compromised, but on how much risk or damage the breach caused for companies, insurers and users or account holders. In some cases, passwords and other information were well protected by encryption, so a password reset eliminated the bulk of the risk.

1. Yahoo

Date: 2013-14
Impact: 1.5 billion user accounts
Details: In September 2016, the once dominant Internet giant, while in negotiations to sell itself to Verizon, announced it had been the victim of the biggest data breach in history, likely by “a state-sponsored actor,” in 2014. The attack compromised the real names, email addresses, dates of birth and telephone numbers of 500 million users. The company said the “vast majority” of the passwords involved had been hashed using the robust bcrypt algorithm.

A couple of months later, in December, it buried that earlier record with the disclosure that a breach in 2013, by a different group of hackers had compromised 1 billion accounts. Besides names, dates of birth, email addresses and passwords that were not as well protected as those involved in 2014, security questions and answers were also compromised.

The breaches knocked an estimated $350 million off Yahoo’s sale price. Verizon eventually paid $4.48 billion for Yahoo’s core Internet business. The agreement called for the two companies to share regulatory and legal liabilities from the breaches. The sale did not include a reported investment in Alibaba Group Holding of $41.3 billion and an ownership interest in Yahoo Japan of $9.3 billion.

Yahoo, founded in 1994, had once been valued at $100 billion. After the sale, the company changed its name to Altaba, Inc.

Read more about the Yahoo data breach…

2. Adult Friend Finder

Date: October 2016
Impact: More than 412.2 million accounts
Details: The FriendFinder Network, which included casual hookup and adult content websites like Adult Friend Finder, Penthouse.com, Cams.com, iCams.com and Stripshow.com, was breached sometime in mid-October 2016. Hackers collected 20 years of data on six databases that included names, email addresses and passwords.

Most of the passwords were protected only by the weak SHA-1 hashing algorithm, which meant that 99 percent of them had been cracked by the time LeakedSource.com published its analysis of the entire data set on November 14.

CSO Online’s Steve Ragan reported at the time that, “a researcher who goes by 1×0123 on Twitter and by Revolver in other circles posted screenshots taken on Adult Friend Finder (that) show a Local File Inclusion vulnerability (LFI) being triggered.” He said the vulnerability, discovered in a module on the production servers used by Adult Friend Finder, “was being exploited.”

AFF Vice President Diana Ballou issued a statement saying, “We did identify and fix a vulnerability that was related to the ability to access source code through an injection vulnerability.”

Read more about the Adult Friend Finder data breach…

3. eBay

Date: May 2014
Impact: 145 million users compromised
Details: The online auction giant reported a cyberattack in May 2014 that it said exposed names, addresses, dates of birth and encrypted passwords of all of its 145 million users. The company said hackers got into the company network using the credentials of three corporate employees, and had complete inside access for 229 days, during which time they were able to make their way to the user database.

It asked its customers to change their passwords, but said financial information, such as credit card numbers, was stored separately and was not compromised. The company was criticized at the time for a lack of communication informing its users and poor implementation of the password-renewal process.

CEO John Donahue said the breach resulted in a decline in user activity, but had little impact on the bottom line – its Q2 revenue was up 13 percent and earnings up 6 percent, in line with analyst expectations.

Read more about the eBay data breach…

4. Equifax

Date: July 29 2017

Impact: Personal information (including Social Security Numbers, birth dates, addresses, and in some cases drivers’ license numbers) of 143 million consumers; 209,000 consumers also had their credit card data exposed.

Details: Equifax, one of the largest credit bureaus in the U.S., said on Sept. 7, 2017 that an application vulnerability on one of their websites led to a data breach that exposed about 143 million consumers. The breach was discovered on July 29, but the company says that it likely started in mid-May.

Read more about the Equifax breach…

5. Heartland Payment Systems

Date: March 2008
Impact: 134 million credit cards exposed through SQL injection to install spyware on Heartland’s data systems.
Details: At the time of the breach, Heartland was processing 100 million payment card transactions per month for 175,000 merchants – most small- to mid-sized retailers. It wasn’t discovered until January 2009, when Visa and MasterCard notified Heartland of suspicious transactions from accounts it had processed.

Among the consequences were that Heartland was deemed out of compliance with the Payment Card Industry Data Security Standard (PCI DSS) and was not allowed to process the payments of major credit card providers until May 2009. The company also paid out an estimated $145 million in compensation for fraudulent payments.