EternalBlue was so valuable, former N.S.A. employees said, that the agency never seriously considered alerting Microsoft about the vulnerabilities, and held on to it for more than five years before the breach forced its hand. The Baltimore attack, on May 7, was a classic ransomware assault. City workers’ screens suddenly locked, and a message in flawed English demanded about $100,000 in Bitcoin to free their files: “We’ve watching you for days,” said the message, obtained by The Baltimore Sun. “We won’t talk more, all we know is MONEY! Hurry up!” Today, Baltimore remains handicapped as city officials refuse to pay, though workarounds have restored some services. Without EternalBlue, the damage would not have been so vast, experts said. The tool exploits a vulnerability in unpatched software that allows hackers to spread their malware faster and farther than they otherwise could. North Korea was the first nation to co-opt the tool, for an attack in 2017 — called WannaCry — that paralyzed the British health care system, German railroads and some 200,000 organizations around the world. Next was Russia, which used the weapon in an attack — called NotPetya — that was aimed at Ukraine but spread across major companies doing business in the country. The assault cost FedEx more than $400 million and Merck, the pharmaceutical giant, $670 million. The damage didn’t stop there. In the past year, the same Russian hackers who targeted the 2016 American presidential election used EternalBlue to compromise hotel Wi-Fi networks. Iranian hackers have used it to spread ransomware and hack airlines in the Middle East, according to researchers at the security firms Symantec and FireEye. “It’s incredible that a tool which was used by intelligence services is now publicly available and so widely used,” said Vikram Thakur, Symantec’s director of security response.
Growing numbers of US cities—with crumbling digital infrastructure and limited defence resources—are being targeted by hackers using malware developed by the country's National Security Agency (NSA). In April 2017, EternalBlue, a powerful exploit developed by the NSA to target a flaw in Microsoft’s software, was dumped online by the as-yet-unidentified Shadow Brokers. It was used by foreign hackers in the global WannaCry and NotPetya cyber attacks, causing losses in the billions of dollars.