Deloitte said Monday that "very few" of the accounting and consultancy firm's clients were affected by a hack after a news report said systems of blue-chip clients had been breached.
Security researchers say hackers compromised popular computer-cleaning software as part of a sophisticated attack that targeted several high-profile technology companies.
Premera Blue Cross said Tuesday its computer network had been hacked, potentially exposing data from 11 million people, in the second recent such attack on a major US health insurer.
The popular New York Times website returned to service Wednesday after hackers forced it down for nearly a day, with a group backing Syria's government claiming responsibility.
Microsoft joined Facebook and Apple on the list of US technology titans targeted in recent cyberattacks.
Facebook said Friday its computer system was "targeted in a sophisticated attack" last month, but that it found no evidence any user data was compromised.
US videogame giant Electronic Arts (EA) on Friday revealed that hackers had looted user data in "a highly sophisticated" attack.
(AP) -- Top-level data breaches often start at the bottom of the ladder. That's a lesson RSA, one of the world's premier computer security firms, learned the hard way.
The world's biggest maker of data storage computers on Thursday said that its security division has been hacked, and that the intruders compromised a widely used technology for preventing computer break-ins.