Staff email credentials and some user data, including email and postal addresses, were taken.
It's fighting an effort to seize Iran's, Syria's and North Korea's domains in a civil settlement, saying they aren't property.
The freedom and openness of the Internet are at stake after the U.S. government announced plans to end its contractual oversight of ICANN, some critics said Thursday.
The NTIA plans to let its domain-name contract with ICANN expire in late 2015, its administrator says. ICANN will then develop its own Internet governance model.