The firm's public disclosure of the breach comes after an article published in The Wall Street Journal on Tuesday revealed that hackers had gained access to the computer networks of several major Wall Street firms, citing Cravath along with others including Weil, Gotshal & Manges.

A statement from the firm reads: 'We have worked closely with law enforcement authorities who have jurisdiction over this matter, and we are not aware that any of the information that may have been accessed has been used improperly.'

However, the WSJ reports that federal investigators are currently looking into whether the cybercriminals targeting the law firms may have been seeking to access data from large M&A firms for the purpose of insider trading.

Sources: The Wall Street Journal; The American Lawyer