US federal authorities late Monday arrested a female hacker, alias "erratic," on charges of stealing personal information from more than 100 million Capital One credit card applications.

Europol has identified the financial sector as one of the most vulnerable to cyberattacks, especially those resulting in data breaches.

What we know about the hack:

• Those affected include 100 million people in the US and 6 million in Canada.

• The victims were mostly consumers and small businesses.

• Information about credit limits, balances, transaction information and Social Security numbers were compromised.

• "Other entities" besides Capital One may have been targeted.

'Deeply sorry'

The US attorney's office in Washington said: "The intrusion occurred though a misconfigured web application firewall that enabled access to the data."

The suspect posted to her Twitter account: "I've basically strapped myself with a bomb vest, f***ing dropping Capital One's dox and admitting it."

Capital One CEO Richard Fairback said in a statement: While I am grateful that the perpetrator has been caught, I am deeply sorry for what has happened. I sincerely apologize for the understandable worry this incident must be causing those affected and I am committed to making it right."

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