This hasn't happened—yet. But Bruce Schneier, an experienced Internet security expert with a track record of calling attention to little problems before they become big ones, is saying he's seeing signs that somebody may be considering an all-out attack on the Internet. In an essay he posted last month called "Someone Is Learning How to Take Down the Internet," he tells us that several Internet-related companies which perform essential functions such as running domain-name servers (DNS) have come to him recently to report a peculiar kind of distributed denial-of-service (DDOS) attack.
For those who may not have read last week's blog about ICANN, let's back up and do a little Internet 101. The URLs you use to find various websites end in domain names—for example, .com or .org. One company that has gone public on its own with some limited information about the attacks is Verisign, a Virginia-based firm whose involvement with the Internet goes back to the 1990s, when they served as the kind of Internet telephone book for every domain ending in .com for a while, before the ICANN, now an internationally-governed nonprofit organization, took over that job. Without domain-name servers, networked computers can't figure out how to find websites, and the whole Internet communication process pretty much grinds to a halt. So the DNS function is pretty important.
As Schneier explains in his essay, companies such as Verisign have been experiencing DDOS attacks that start small and ramp up over a period of time. He likens them to the way the old Soviet Union used to play tag with American air defenses and radar sites in order to see how good they were, in case they ever had to mount an all-out attack. From the victim's point of view, a DDOS attack would be like if you were an old-fashioned telephone switchboard operator, and all your incoming-call lights lit up at once—for hours, or however long the attack lasts. It's a battle of bandwidths, and if the attacker generates enough dummy requests over a wide enough bandwidth (meaning more servers and more high-speed Internet connections), the attack overwhelms the victim's ability to keep answering the phone, so to speak. Legitimate users of the attacked site are blocked out and simply can't connect as long as the attack is effective. If a critical DNS is attacked, it's a good chance that most of the domain names served will also disappear for the duration. That hasn't happened yet on a large scale, but some small incidents have occurred along these lines recently, and Schneier thinks that somebody is rehearsing for a large-scale attack.
The Internet was designed from the start to be robust against attack, but back in the 1970s and 1980s, the primary fear was an attack on the physical network, not one using the Internet itself. Nobody goes around chopping up fiber cables in hopes of bringing down the Internet, because it's simply not that vulnerable physically. But it's likely that few if any of the originators thought of the possibility that the Internet's strengths—universal access, global reach—would be turned against it by malevolent actors. It's also likely that few of them may have believed in original sin, but that's another matter.
Who would want to take down the Internet? For the rest of the space here I'm going to engage in a little dismal speculation, starting with e-commerce. Whatever else happens if the Internet goes down, you're not going to be able to buy stuff that way. Schneier isn't sure, but he thinks these suspicious probing attacks may be the work of a "state actor," namely Russia or China. Independent hackers, or even criminal rings, seldom have access to entire city blocks of server farms, and high-bandwidth attacks like these generally require such resources.
If one asks the simple question, "What percent of retail sales are transacted over the Internet for these three countries: China, the U. S., and Russia?" one gets an interesting answer. It turns out that as of 2015, China transacted about 12.9% of all retail sales online. The U. S. was next, at about 8.1%. Bringing up the rear is Russia, at around 2%, which is where the U. S. was in 2004. Depending on how it's done, a massive attack on DNS sites could be designed to damage some geographic areas more than others, and without knowing more details about China's Internet setup I can't say whether China could manage to cripple the Internet in the U. S. without messing up its own part. But there is so much U. S.-China trade that Chinese exports would start to suffer pretty fast anyway. So there are a couple of reasons that if China did anything along these lines, they would be shooting themselves in the foot, so to speak.
Russia, on the other hand, has much less in the way of direct U. S. trade, and while it would be inconvenient for them to lose the use of the Internet for a while, their economy, such as it is, would suffer a much smaller hit. So based purely on economic considerations, my guess is that Russia would have more to gain and less to lose in an all-out Internet war than China would.
A total shutdown of the Internet is unlikely, but even a partial shutdown could have dire consequences. Banks use the Internet. Lots of essential utility services, ranging from electric power to water and natural gas, use the Internet for what's called SCADA (supervisory control and data acquisition) functions. The Internet has gradually become critical piece of infrastructure whose vulnerabilities have never been fully tested in an all-out attack. It's not a comfortable place for a country to be in, and in these days of political uncertainty and the waning of dull, expert competence in the upper reaches of government, you hope that someone, somewhere has both considered these possibilities in detail, and figured out some kind of contingency plan to act on in case it happens.
If there is such a plan, I don't know about it. Maybe it's secret and we shouldn't know. But if it's there, I'd at least like to know that we have it. And if we don't, maybe we should make plans on our own for the Day The Internet Goes Down.
Sources: Bruce Schneier's essay "Someone Is Learning How to Take Down the Internet" can be found at https://www.schneier.com/blog/archives/2016/09/someone_is_lear.html. I obtained statistics on the percent of U. S. retail e-commerce sales from the website https://ycharts.com/indicators/ecommerce_sales_as_percent_retail_sales, the China data from https://www.internetretailer.com/2016/01/27/chinas-online-retail-sales-grow-third-589-billion-2015, and the Russia data from https://www.internetretailer.com/commentary/2016/02/08/russian-e-commerce-domestic-sales-slump-chinese-imports-soar. I also referred to the Wikipedia article on Verisign.