The concept is simple: Your computer gets infected with a virus that encrypts your files until you pay a ransom. It's extortion taken to its networked extreme. The criminals provide step-by-step instructions on how to pay, sometimes even offering a help line for victims unsure how to buy bitcoin. The price is designed to be cheap enough for people to pay instead of giving up: a few hundred dollars in many cases. Those who design these systems know their market, and it's a profitable one.
The ransomware that has affected systems in more than 150 countries recently, WannaCry, made press headlines last week, but it doesn't seem to be more virulent or more expensive than other ransomware. This one has a particularly interesting pedigree: It's based on a vulnerability developed by the National Security Agency that can be used against many versions of the Windows operating system. The NSA's code was, in turn, stolen by an unknown hacker group called Shadow Brokers widely believed by the security community to be the Russians in 2014 and released to the public in April.
Microsoft patched the vulnerability a month earlier, presumably after being alerted by the NSA that the leak was imminent. But the vulnerability affected older versions of Windows that Microsoft no longer supports, and there are still many people and organizations that don't regularly patch their systems. This allowed whoever wrote WannaCry -- it could be anyone from a lone individual to an organized crime syndicate -- to use it to infect computers and extort users.
The lessons for users are obvious: Keep your system patches up to date and regularly backup your data. This isn't just good advice to defend against ransomware, but good advice in general. But it's becoming obsolete.
This article is by internationally-renowned security technologist Bruce Schneier and this excerpt is published here with permission. Read the full article at Bruce's Schneier on Security blog.