Introduction
Overview
In May of 2017, the ransomware worm known as WannaCry infected numerous organizations, causing significant damage. Over 200,000 systems were infected across 150 countries, with damages in the hundreds of millions of dollars. Prominent victims of WannaCry included Boeing, Honda, the NHS of England and Scotland, and the University of Montreal. The ransomware demanded a $300 Bitcoin payment in exchange for the decryption of the victim's files, with the amount increasing over time if left unpaid. On the same day of WannaCry's release, a hardcoded kill switch was discovered and promptly registered by a security researcher. While this did not help systems already infected, it effectively halted further spread of WannaCry within a matter of hours.
Vulnerability Details
WannaCry used the previously undisclosed EternalBlue vulnerability (CVE-2017-0144), which takes advantage of SMBv1 mishandling specially crafted packets, allowing for remote code execution. A backdoor implant tool known as DoublePulsar is also used. The tool is able to run in system memory, allowing it to stealthily install malware on the host. Both EternalBlue and DoublePulsar were believed to be originally developed by the NSA, and later stolen by the hacking group known as The Shadow Brokers, meaning they were not publicly known. Such vulnerabilities are called “Zero Days”, referring to the amount of days the vulnerability's existence has been known. Since previously unknown, security professionals have to begin developing patches the same day of release.