In-depth article: https://www.nytimes.com/2017/05/13/world/asia/cyberattacks-online-security-.html
The program is likely based off of a leaked NSA hacking tool EternalBlue that utilizes a vulnerability in unpatched and pirated Windows systems. Limiting the scope of damage in North America was the discovery of a website-based kill switch by a researcher, who bought the domain name and halted the spread of the ransomware.
Questions have been raised whether this attack was merely to cause damage rather than profit. One thing is for certain, the specter of cybercriminals potentially disrupting computer systems on a mass global scale has risen.
Later updates and economic considerations of WannaCry here: https://www.cbsnews.com/news/wannacry-ransomware-attacks-wannacry-virus-losses/
Conjecture
What if next time these hackers turn their attention to a digital financial exchange like those in New York or London (think of the "digital bomb" planted in the Nasdaq back in 2010)? The internet is both wonderful and dangerous, but this attack shows it may not take much to bring down the house.
News of WannaCry will most likely see the stock prices of cybersecurity firms bid sharply up as companies seek to protect themselves from digital attacks. Some months back I wasn't sure what to make of cybersecurity ETFs, but the author is sure that the creator of the ETF "HACK" has seen some reward around the uncertainty of ransomware.
