New York (CNN Business) — In one of the biggest-ever data breaches, a hacker gained access to more than 100 million Capital One customers’ accounts and credit card applications earlier this year.
Paige Thompson is accused of breaking into a Capital One server and gaining access to 140,000 Social Security numbers, 1 million Canadian Social Insurance numbers and 80,000 bank account numbers, in addition to an undisclosed number of people’s names, addresses, credit scores, credit limits, balances, and other information, according to the bank and the US Department of Justice.
A criminal complaint says Thompson tried to share the information with others online. The 33-year-old, who lives in Seattle, had previously worked as a tech company software engineer for the cloud hosting company that Capital One was using, the DOJ said. She was able to gain access by exploiting a misconfigured web application firewall, according to a court filing.
Thompson was arrested Monday in connection with the breach, the Justice Department said. Thompson’s attorney could not be immediately reached for comment.
Capital One (COF) said the hack occurred March 22 and 23. The company indicated it fixed the vulnerability and said it is “unlikely that the information was used for fraud or disseminated by this individual.” However, the company is still investigating.
“I sincerely apologize for the understandable worry this incident must be causing those affected and I am committed to making it right,” said Capital One CEO Richard Fairbank in a statement.
The breach affected around 100 million people in the United States and about 6 million people in Canada, according to Capital One.
However, “no credit card account numbers or log-in credentials were compromised and over 99% of Social Security numbers were not compromised,” the company said.
The criminal complaint against Thompson paints a picture of a less-than-careful suspect. Thompson posted the information on GitHub, using her own name, the complaint says, adding that she also indicated on social media that she had Capital One information.
The FBI special agent who investigated Thompson believes Thompson tweeted that she wanted to distribute Social Security numbers along with full names and dates of birth.
The complaint indicates Thompson “recognizes that she has acted illegally.”
Capital One said it will notify people affected by the breach and will make free credit monitoring and identity protection available. The company expects to incur between $100 million and $150 million in costs related to the hack, including customer notifications, credit monitoring, tech costs and legal support due to the hack.
Capital One’s stock was down 4% after hours late Monday night.