A 22-year-old British cybersecurity researcher thwarted yesterday's "Wanna Decryptor 2.0" cyberattack that affected computers worldwide by spending nearly $11, the Washington Post reports.

The "kill switch": The cybersecurity expert figured out there was a hidden "kill switch" (an unregistered domain) within the malware that was locking users out of their computers. By buying a domain ending with "gwea.com" and registering a website, all for $10.69, he was able to activate the hidden kill switch — potentially saving companies worldwide billions of dollars.

Read the entire process of how this 22-year-old stopped a global cybersecurity attack on his blog.