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The Capital One breach is unlike any other major hack, with allegations of a single engineer wreaking havoc

Key Points
  • The Capital One breach involves the theft of more than 100 million customer records, 140,000 Social Security numbers and 80,000 linked bank details of Capital One customers, allegedly stolen by a single insider, according to court filings in Seattle.
  • The details set it apart from breaches of companies such as Equifax and Marriott, which were attacked from the outside by criminals with a nation-state connection.
  • Instead, according to the indictment of Paige A. Thompson, she was able to exploit a loophole in a Capital One application's firewall to gain access to the information.
Capital One CEO and Chairman, Richard Fairbank.
Marvin Joseph| The Washington Post | Getty Images

Capital One is dealing with what will likely be one of the most important data breaches of the year.

The incident involved theft of more than 100 million customer records, 140,000 Social Security numbers and 80,000 linked bank details of Capital One customers, according to court filings in Seattle. But the Capital One incident is significant beyond the numbers, because it was allegedly carried out by a lone wolf.

The details set it apart from breaches of companies such as Equifax and Marriott, which were attacked from the outside by criminals with a nation-state connection. It's also different from the spate of ransomware attacks against major U.S. cities, which were likely committed by groups of individuals outside the U.S.

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Here's what we know about the Capital One data breach

Instead, according to the indictment of Paige A. Thompson, the experienced engineer was able to exploit a flaw in an application firewall stored on an Amazon Web Services cloud server to gain access to the information.

An Amazon spokesperson confirmed Thompson had worked for Amazon but she left in 2016. The breach took place between March and July this year. Capital One confirmed in a statement Monday that the incident was related to a misconfigured application firewall and not an issue with cloud infrastructure.

"AWS was not compromised in any way and functioned as designed," Amazon said in a statement, adding that the reason for the breach was a misconfiguration of firewall settings on a web application, managed on the cloud server by Capital One, not a vulnerability in the cloud server itself.

The incident, which is still unraveling, will bring up major issues facing the biggest tech companies, cloud firms and banks, namely how to control who has access to sensitive consumer data and detect insiders who may go rogue.

An unlikely scenario

In many ways, it's the nightmare scenario for a large company. Banks such as Capital One have in recent years become much more adept at protecting against outside threats that target sensitive personal data. But protecting against a single individual bent on destruction and with even a modicum of access can be much harder.

According to the indictment, Thompson exploited a misconfigured firewall in a cloud server used by Capital One. She allegedly used a Tor browser, which anonymizes a person's online activities, to gain this access. She also used a virtual private network known as IPredator to further obscure her activities, according to the indictment.

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Capital One believes breach will cost up to $150 million

All of these factors combined with the possibility of insider knowledge means this incident will be closely watched by cybersecurity professionals and banks, particularly to see whether there was any way Capital One could have avoided the incident under the circumstances.

"Capital One had some good security practices in place," said Sam Curry, chief security officer of cybersecurity company Cybereason. "As a positive, they made an arrest quickly and there is a chance to minimize damage. Normally, it's months, years or never in terms of arrests and accountability of the criminals. Finding things sooner in the life cycle always limits the impact and damage to the innocent."

Capital One's stock closed down 5.89% on Tuesday.

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