WannaCry is the latest outbreak of vicious malware to hit the internet. It’s a form of ransomware – malware that’s designed to take your computer and personal files “hostage” by encrypting them until a “ransom” is paid to the malware’s creators. It is believed to have started out as a phishing attack and then quickly spread by exploiting a recently disclosed vulnerability in the Windows operating system. Once activated, it displays a demand for payment to unlock the user’s files. The price to decrypt the files escalates the longer a user waits, eventually resulting in a permanent system lock.

While ransomware is common enough, WannaCry stands out for the remarkable speed of the outbreak. In only 4 days, the infection had spread to over 200,000 systems, compromising high-profile networks like the National Health Service of England and Telefónica.

This is largely due to the fact that the infection spread via a zero-day exploit used by the NSA as a tool of cyber warfare. When the vulnerability was stolen from the NSA in April, it is believed that it fell into the hands of organized crime leading to the WannaCry outbreak.

Microsoft has subsequently criticized the US government’s stockpiling of zero-day exploits and called for a different approach to ensure that these cyber weapons do not fall into the wrong hands. They even went as far as releasing security patches for the now unsupported Windows XP and Windows Server 2003 operating systems to help stop the spread of this malicious infection. Due to the rapid industry response, the rate of the infection is slowing.