The attack affected Tribune Publishing Co. , which owns the Chicago Tribune, the Baltimore Sun, the New York Daily News and the Sun-Sentinel in South Florida, among others.
The Los Angeles Times and San Diego Union-Tribune, which were sold by Tribune Publishing this year but still share production platforms with their former parent, said they were also affected.
Tribune Publishing said it first detected the presence of “malware” in its computer systems Friday and took steps to enhance its security. The malware affected the “timeliness and completeness” of its printed newspapers in many of its markets, a spokeswoman said.
The company has reported the matter to the FBI, the spokeswoman said.
Tribune Publishing said there was “no evidence that customer credit card information or personally identifiable information has been compromised.”
The San Diego Union-Tribune said other newspapers printed at the Olympic printing plant in Los Angeles were also affected, including editions of the New York Times and The Wall Street Journal.
Representatives for The Wall Street Journal and the New York Times didn’t immediately respond to a request for comment.
Tribune Publishing, which until October was known as Tronc, recently sold the Los Angeles Times, the San Diego Union-Tribune and a group of smaller newspapers to Dr. Patrick Soon-Shiong, a billionaire biotechnology entrepreneur, for about $500 million.