Security researchers have been unable to find a "kill switch" for the latest cyberattack hitting systems around the world—but they have developed a vaccine. Researchers say that the Petya ransomware will not encrypt files on computers that have the read-only file "C:\Windows\perfc.dat," the BBC reports. A guide on how to set that up can be found here, though security experts say people running up-to-date versions of Windows will already be protected. And the fix isn't perfect: Researchers warn that although the "vaccination" will make individual computers immune to the attack, the computers could still become "carriers" capable of spreading the malware to others.
The cyberattack, which is believed to have originated in a software update for a Ukrainian tax accounting system, spread rapidly around the world Tuesday, with victims including India's largest container port, Russia's biggest oil company, a chocolate factory in Tasmania, and a hospital in Pittsburgh, reports Reuters. The malware encrypted hard drives and demanded $300 in bitcoin to restore files. Around 30 people paid up, though the mailbox involved has now been blocked, Business Insider reports. Analysts tell the Guardian that the low financial return and ineffective payment mechanism suggest that the attack was designed not to make money but to cause chaos in Ukraine, the most affected country.