Three Lines of Defense against Ransomware Attacks

Criminals go where the money is, and cybercriminals are no exception.

And right now, the money is in ransomware.

It's a simple scam. Encrypt the victim's hard drive, then extract a fee to decrypt it. The scammers can't charge too much, because they want the victim to pay rather than give up on the data. But they can charge individuals a few hundred dollars, and they can charge institutions like hospitals a few thousand. Do it at scale, and it's a profitable business.

And scale is how ransomware works. Computers are infected automatically, with viruses that spread over the internet. Payment is no more difficult than buying something online — and payable in untraceable bitcoin — with some ransomware makers offering tech support to those unsure of how to buy or transfer bitcoin. Customer service is important; people need to know they'll get their files back once they pay.

And they want you to pay. If they're lucky, they've encrypted your irreplaceable family photos, or the documents of a project you've been working on for weeks. Or maybe your company's accounts receivable files or your hospital's patient records. The more you need what they've stolen, the better.

The particular ransomware making headlines is called WannaCry, and it's infected some pretty serious organizations.

What can you do about it? Your first line of defense is to diligently install every security update as soon as it becomes available, and to migrate to systems that vendors still support. Microsoft issued a security patch that protects against WannaCry months before the ransomware started infecting systems; it only works against computers that haven't been patched. And many of the systems it infects are older computers, no longer normally supported by Microsoft — though it did belatedly release a patch for those older systems. I know it's hard, but until companies are forced to maintain old systems, you're much safer upgrading.

This is easier advice for individuals than for organizations. You and I can pretty easily migrate to a new operating system, but organizations sometimes have custom software that breaks when they change OS versions or install updates. Many of the organizations hit by WannaCry had outdated systems for exactly these reasons. But as expensive and time-consuming as updating might be, the risks of not doing so are increasing.

Your second line of defense is good antivirus software. Sometimes ransomware tricks you into encrypting your own hard drive by clicking on a file attachment that you thought was benign. Antivirus software can often catch your mistake and prevent the malicious software from running. This isn't perfect, of course, but it's an important part of any defense.

Your third line of defense is to diligently back up your files. There are systems that do this automatically for your hard drive. You can invest in one of those. Or you can store your important data in the cloud. If your irreplaceable family photos are in a backup drive in your house, then the ransomware has that much less hold on you. If your e-mail and documents are in the cloud, then you can just reinstall the operating system and bypass the ransomware entirely. I know storing data in the cloud has its own privacy risks, but they may be less than the risks of losing everything to ransomware.

That takes care of your computers and smart phones, but what about everything else? We're deep into the age of the "Internet of things."

There are now computers in your household appliances. There are computers in your cars and in the airplanes you travel on. Computers run our traffic lights and our power grids. These are all vulnerable to ransomware. The Murai botnet exploited a vulnerability in internet-enabled devices like DVRs and webcams to launch a denial-of-service attack against a critical internet name server; next time it could just as easily disable the devices and demand payment to turn them back on.

Re-enabling a webcam will be cheap; re-enabling your car will cost more. And you don't want to know how vulnerable implanted medical devices are to these sorts of attacks.

Commercial solutions are coming, probably a convenient repackaging of the three lines of defense described above. But it'll be yet another security surcharge you'll be expected to pay because the computers and internet-of-things devices you buy are so insecure. Because there are currently no liabilities for lousy software and no regulations mandating secure software, the market rewards software that's fast and cheap at the expense of good. Until that changes, ransomware will continue to be profitable line of criminal business.

Categories: Computer and Information Security

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Schneier on Security is a personal website. Opinions expressed are not necessarily those of IBM Resilient.