Internet outages continued into Friday afternoon, with major websites seeming to flicker an and off for internet users across the United States.
The cause was a major, ongoing distributed denial of service (DDoS) attack—when hackers flood a website with traffic so it can’t handle visits from ordinary web users—on critical web infrastructure.
Among the major sites that had trouble staying online or functioning properly: The New York Times, Twitter, Pinterest, Reddit, GitHub, Etsy, Tumblr, Spotify, PayPal, Verizon, Comcast, EA, and the Playstation network. Aside from the inconvenience to those attempting to visit those sites, there’s the question of how an attack like this affects the companies who run those sites. System outages—even seemingly brief ones—can have huge repercussions on the bottom line.
For more than one-third of companies, a single hour of a DDoS attack can cost up to $20,000, according to a 2014 report by the security firm Imperva Incapsula. (For some companies, the cost of an attack can exceed $100,000 per hour.) Given that the majority of attacks continue for more than six hours, these losses add up quickly. In a particularly stark example, the airline Virgin Blue lost $20 million in period of IT outages that spanned 11 days in 2010.