The websites Newsday.com and News12.com were hacked but now are fully operational, officials said Thursday.
Kelly McAndrew, a vice president for Cablevision Systems Corp., which owns both sites, confirmed the attack had occurred. She declined to say how long the sites were affected, but said the problems had been resolved.
"An unauthorized third party illegally accessed the content management system" for the sites, "which led certain Web browsers to post a temporary warning page," McAndrew said.
The browsers were Google Chrome and Firefox, according to sources familiar with the matter.
McAndrew said none of Cablevision's other websites were affected.
"We have eliminated this problem and instituted additional security measures to protect against future incidents," she said. "We are currently working with security and browser companies to remove the warning pages."
The warnings said the websites could have been compromised by malware or a virus.
McAndrew said no customer information "was compromised" by the attack. News organizations often are targets of computer hackers.