Foreign hackers infiltrated computer systems shared by several major US newspapers, "crippling" newspaper production and delivery systems across the country on Saturday, according to the Los Angeles Times, citing a source with knowledge of the situation.

LA Times Olympic printing plant (Photo: doobybrain.com)

The attacks, which began alte Thursday night, appear "to have originated from outside the United States," according to the Times, and resulted in distribution delays in the Saturday edition of The Times, the San Diego Union-Tribune, the Chicago Tribune, Baltimore Sun and several other major newspapers which share the same production platform.

West coast editions of the Wall Street Journal and New York Times were also affected, as they are all printed at the LA Times' Olympic printing plant in downtown Los Angeles.

The hackers were able to disable several crucial software systems which store news stories, photographs and administrative information - which complicated efforts to make the physical plates used to print the papers at The Times' downtown plant.

"We believe the intention of the attack was to disable infrastructure, more specifically servers, as opposed to looking to steal information," according to the source who wishes to remain anonymous.

All papers within The Times’ former parent company, Tribune Publishing, experienced glitches with the production of papers. Tribune Publishing sold The Times and the San Diego Union-Tribune to Los Angeles businessman Dr. Patrick Soon-Shiong in June, but the companies continue to share various systems, including software. “Every market across the company was impacted,” said Marisa Kollias, spokeswoman for Tribune Publishing. She declined to provide specifics on the disruptions, but the company properties include the Chicago Tribune, Baltimore Sun, Annapolis Capital-Gazette, Hartford Courant, New York Daily News, Orlando Sentinel and Fort Lauderdale Sun-Sentinel. Tribune Publishing said in a statement Saturday that “the personal data of our subscribers, online users, and advertising clients has not been compromised. We apologize for any inconvenience and thank our readers and advertising partners for their patience as we investigate the situation. News and all of our regular features are available online.” -LA Times

"We are trying to do work-arounds so we can get pages out. It’s all in production. We need the plates to start the presses. That’s the bottleneck," said Director of Distribution, Joe Robidoux.

The problem was first detected Friday, however technology teams were unable to completely fix all systems before press time. It is unknown whether the company has contacted law enforcement regarding the incident.

South Florida readers of the Sun-Sentinel were told that it had been "crippled this weekend by a computer virus that shut down production and hampered phone lines," according to its website. The New York Times and Palm Beach Post readers in South Florida also failed to receive their Saturday papers since they use the Sun-Sentinel's printing facility.

"Usually when someone tries to disrupt a significant digital resource like a newspaper, you’re looking at an experienced and sophisticated hacker," said Pam Dixon, executive director of nonprofit public interest research group the World Privacy Forum.

Dixon added that malware has become more sophisticated and coordinated over time, involving more planning by hacking networks who work together to infiltrate a system over time.

"Modern malware is all about the long game," she said. "It’s serious attacks, not small stuff anymore. When people think of malware, the impression may be, ‘It’s a little program that runs on my computer,’" added Dixon.

With modern hacking, "malware can root into the deepest systems and disrupt very significant aspects of those systems."