Cyberattack Forces Nucor to Halt Some Operations Amid Ongoing Investigation

 

Nucor, the largest steel manufacturer and recycler in North America, has disclosed a cybersecurity incident that forced the company to temporarily shut down some of its production operations. The Charlotte, North Carolina-based firm confirmed the event in a recent 8-K filing with the U.S. Securities and Exchange Commission (SEC), citing unauthorized third-party access to certain information technology systems. The breach prompted the company to activate its incident response plan. 

As a precautionary measure, Nucor took potentially affected systems offline, halted operations at undisclosed locations, and implemented containment and recovery procedures. The exact nature of the cyberattack has not been revealed, but the move to suspend operations has raised concerns over the potential severity of the incident. “Out of an abundance of caution,” the company stated, some facilities paused operations temporarily, though it did not identify which of its roughly 300 locations across the U.S., Canada, and Mexico were affected. 

Nucor emphasized that it is working to restore operations and resume full functionality as swiftly and safely as possible. The incident comes at a time when large manufacturers are increasingly targeted by cybercriminals aiming to exploit critical infrastructure for financial gain, intellectual property theft, or even geopolitical motives. Industry experts suggest that the operational disruption and limited communication from affected sites point toward a potential ransomware attack, although no group has claimed responsibility so far. 

In Q1 2025 alone, Nucor reported $7.83 billion in sales and employs around 25,000 people. It is also undertaking a major $3 billion expansion project in West Virginia, underscoring the scale and significance of its operations within the U.S. industrial sector. Cyberattacks on industrial firms are becoming more frequent. Recent 8-K filings related to cyber incidents have also come from companies like Masimo (medical technology), Sensata (industrial sensors), National Presto Industries (appliances), and Microchip Technology (semiconductors). 

Globally, firms in the U.K. and Switzerland have reported similar disruptions over the past year, highlighting a rising trend in targeted attacks on manufacturers. Given Nucor’s integral role in the U.S. supply chain, any disruption has broader implications. While no sensitive data leaks have been reported, the investigation is ongoing and law enforcement has been notified. 

Cybersecurity experts continue to urge industrial companies to invest in stronger digital defenses, especially as reliance on connected systems grows.