What Is a Distributed Denial-of-Service Attack and How Did It Break Twitter?

On Friday, multiple distributed denial-of-service (DDoS) attacks hit the Internet services company Dyn. The cyberattack prevented many users on the U.S. East Coast from navigating to the most popular websites of Dyn customers, which include Twitter, Reddit, and Netflix.

Dyn detected the first attack at 7:10 a.m. Eastern time on Friday and restored normal service about two hours later. Then at 11:52 a.m. ET, Dyn began investigating a second attack. By 2:00 p.m., the company said it was still working to resolve “several attacks” at once.

The interruptions inconvenienced many Internet users, and the daily operation of Internet giants in entertainment, e-commerce, and social media. There still aren’t many details available about Dyn’s predicament, and the company did not immediately respond to an interview request. But we do know from Dyn’s posts that the first two assaults on its network were DDoS attacks. Its customers’ outages again show that major Internet companies remain vulnerable to this common hacker scheme—one that has plagued networks since 2000.

A denial-of-service attack aims to slow or stop users from accessing content or services by impeding the ability of a network or server to respond to their requests. The word “distributed” means that hackers executed the Dyn attacks by infecting and controlling a large network of computers called a botnet, rather than running it from a single machine that they own.

Hackers can assemble a botnet by spreading malware, which is often done by prompting unsuspecting users to click a link or download a file. That malware can be programmed to periodically check with a host computer owned by hackers for further instructions. To launch an attack,…[Read more]