A malware attack on software used by Tribune Publishing prevented a number of major newspapers from printing their weekend editions. The affected papers are current and former Tribune properties including the Chicago Tribune, the New York Daily News, The Baltimore Sun, and the Los Angeles Times.
The virus was discovered Friday after it "impacted some back-office systems which are primarily used to publish and produce newspapers across our properties," said a statement from Tribune. "This issue has affected the timeliness and in some cases the completeness of our printed newspapers. Our websites and mobile applications, however, have not been impacted."
The Los Angeles Times reported a "foreign entity" was responsible, but noted "officials said it was too soon to say whether it was carried out by a foreign state or some other entity, said a source with knowledge of the situation."
The Department of Homeland Security is investigating. "We are aware of reports of a potential cyber incident effecting several news outlets," the agency said, "and are working with our government and industry partners to better understand the situation."