Sinclair Broadcast Group Says It Was Hit by a Ransomware Attack

Sinclair Broadcast Group Inc.,

SBGI -3.02%

one of the largest owners of broadcast stations in the U.S., said it is working to contain a cybersecurity incident that disrupted some of its networks and had some of its servers and workstations encrypted with ransomware.

Sinclair said the event, which it identified over the weekend, has caused a disruption, and may continue to do so, to parts of the business, including its local advertisements.

The company said it has yet to determine whether the cyberattack will have a “material impact on its business, operations or financial results.”

Social-media posts from local network anchors and customers on Sunday and early Monday reported Sinclair-owned stations were down. Some Twitter posts noted the outage cut into broadcasts of National Football League games and morning news. Sinclair operates 185 broadcast networks in 86 markets and owns 21 regional sports networks.

In a statement on Monday, Sinclair said it was working with a cybersecurity firm and notified law enforcement and other government agencies.

The company said it was working “to restore operations quickly and securely.”

A spokesman didn’t comment on the magnitude of the breach or provide further comment beyond the statement.

Ransomware attacks are increasing in frequency, victim losses are skyrocketing, and hackers are shifting their targets. WSJ’s Dustin Volz explains why these attacks are on the rise and what the U.S. can do to fight them. Photo illustration: Laura Kammermann

Write to Lillian Rizzo at Lillian.Rizzo@wsj.com

Sinclair Broadcast said the cybersecurity incident has caused a disruption to parts of the business, including its local advertisements.

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