TOKYO—Despite spending weeks to resolve a massive Internet security breach, Sony Corp. Chief Executive Howard Stringer said he can’t guarantee the security of its videogame network or any other Web system in the “bad new world” of cyber crime.

Mr. Stringer’s comments in a phone interview Tuesday with The Wall Street Journal, ahead of a New York roundtable discussion with reporters, come on the heels of a trying month for Sony. The company partially restored two of its online game systems and a streaming movie and music service over the weekend after shutting the services for several weeks when a breach compromised the personal information of more than 100 million account holders.

While Sony has restored part of the PlayStation Network—an online game system for its PlayStation 3 videogame console—in the U.S. and Europe and bolstered security measures, Mr. Stringer, 69 years old, said maintaining the service’s security is a “never-ending process” and he doesn’t know if anyone is “100% secure.”

He said the security breach at PSN, Sony Online Entertainment, an online game service for personal-computer users, and its Qriocity streaming video and music network could lead the way to bigger problems well beyond Sony, or the gaming industry. He warned the attacks may one day target the global financial system, the power grid or air traffic control systems.

“It’s the beginning, unfortunately, or the shape of things to come,” said Mr. Stringer. “It’s not a brave new world; it’s a bad new world,” he said.

The interview and roundtable were Mr. Stringer’s first public comments addressing the security woes, other than a May 5 letter on Sony’s PlayStation blog, apologizing for the inconvenience caused by the suspension of the two services.

Follow this link to read more: