Widespread cyber attack one of the largest ever seen

Hackers unleashed a complex attack on the internet through common devices like webcams and cut access to some of the world’s best-known websites yesterday, in a stunning breach of global internet stability.

The attacks struck Twitter, Paypal, Spotify and other customers of an infrastructure company in New Hampshire called Dyn, which acts as a switchboard for internet traffic.

The attackers used hundreds of thousands of internet-connected devices that had previously been infected with a malicious code that allowed them to cause outages that began in the eastern United States and then spread to other parts of the country and Europe.

‘‘The complexity of the attacks is what’s making it very challenging for us,’’ said Dyn’s chief strategy officer, Kyle York.

The US Department of Homeland Security and the FBI said they were investigating. The disruptions come at a time of unprecedented fears about the cyber threat in the US, where hackers have breached political organisations and election agencies.

Yesterday’s outages were intermittent and varied by area. Users complained that they could not reach dozens of internet destinations. Dyn said the attacks came from millions of internet addresses, making it one of the largest attacks ever seen.

Security experts said it was an especially potent type of distributed denial-of-service attack, in which attackers flood their targets with so much junk traffic that they freeze up.