Governments and companies around the world began to gain the upper hand against the first wave of the unrivaled global cyberattack this morning.
More than 200,000 computers in at least 150 countries have so far been infected, according to Europol, the European Union's law enforcement agency. The U.K.'s National Cyber Security Centre said new cases of so-called ransomware are possible "at a significant scale."
"For now, it does not look like the number of infected computers is increasing," said a Europol spokesman. "We will get a decryption tool eventually, but for the moment, it's still a live threat and we're still in disaster recovery mode."
The initial attack was stifled when a security researcher disabled a key mechanism used by the worm to spread, but experts warned the hackers were likely to mount a second attack because so many users of personal computers with Microsoft operating systems couldn't or didn't download a security patch released in March that Microsoft had labeled "critical."