Internet, Networking, & Security Around the Web What Is a DDoS Attack? Important things to know about denial of service attacks By Jennifer Allen Writer Jennifer Allen has been writing about technology since 2010. Her work has appeared in Mashable, TechRadar, and many more publications. our editorial process Twitter LinkedIn Jennifer Allen Updated March 03, 2020 Around the Web How to Get a VPN Tweet Share Email A DDoS attack is a form of cyber attack that occurs when an online service such as a website or app is made unavailable by overwhelming it with traffic from multiple sources. You may have heard of a denial of service attack in the media any time a website is 'brought down by hackers.' It's useful to understand what a DDoS attack really means. Here's what you need to know about the hack. What Is a DDoS? A DDoS is basically like if a shop was swamped by customers, like on Black Friday, and the shop grinds to a halt because there are just too many people there. Service is massively degraded and everyone ends up unhappy. Sometimes, the shop is forced to close for a time for safety reasons. That's essentially what a DDoS is, but online. A specific, but vital machine or server is targeted, then flooded with attempts to access it, causing the server to get slower and slower and eventually fail. They're often only temporary attacks, but when focused on something important like a Google server or other major website, they can cause significant disruption. DDoS attacks can happen by accident. For instance, if a retailer has a particularly great sale that spreads widely across the internet, too many users can use the site at the same time, causing it to crash for a time. DDoS attacks have been around for as long as online servers have existed with the first widely reported attack occurring in 1995 against sites owned by the French government. Since then, they've rapidly grown in number. How Do DDoS Attacks Happen? DDoS attacks typically take some planning by hackers, but they aren't as hard to arrange as you'd think. Sometimes, hackers can simply overwhelm websites through concerted efforts amongst themselves, but a more likely method is through controlling other PCs that are unwittingly involved. Through the use of viruses and malware, hackers can take control of a computer and use it as what's known as a zombie or bot to then command it to 'attack' the website or server that will be the victim of a DDoS attack. This is known as a botnet where hundreds and sometimes thousands of systems are used at the same time to attack a server. They flood servers with information causing them to eventually go down, denying service to regular users, hence the term denial of service. Why Do DDoS Attacks Happen? Such brute force attacks can happen for many reasons. Sometimes, it can simply be for fun by hackers or as a form of grudge against a particular company or website. Other times, it can expose the failing website to other attacks and make it easier for hackers to access password or security details. It can work as a form of smokescreen so businesses focus on restoring their service rather than take notice of other invasive attacks. Whatever the reason for a DDoS attack, they cost the victim company a lot of money, often in the thousands or more, meaning they're a huge threat. One attack in 2000 by a 15 year old boy, Michael Calce, involved hacking the computer networks of a number of Universities, then using them to bring down several major websites, including CNN, eBay, and Yahoo. Another attack in 2016 brought down Dyn, a major domain name system provider, which in turn brought down AirBnB, CNN, Netflix, PayPal, Spotify, Visa, Amazon, and many more websites. Should I Be Worried About a DDoS Attack? It's very unlikely that anyone would direct a DDoS attack at your home system, but you could inadvertently become part of a botnet that's involved in such an attack. That's why it's important to keep your PC or Mac up to date at all times, as well as be aware of the best ways to protect yourself from viruses and malware. Otherwise, the only way you could be affected by a DDoS attack is if you're trying to browse a website currently under attack. In which case, it's an irritant, but most websites recover pretty fast.