Weekend cyber-attacks include Twitter, Spotify, PayPal and others

How the increasingly connected world is at high risk of cyber-attacks was once again proved last weekend when hackers targeted some of the world’s most popular websites including Twitter, Paypal, Spotify and other customers of an infrastructure company in New Hampshire called Dyn, which acts as a switchboard for internet traffic.

The criminals 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.

Dyn said attacks were coming 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, or DDoS, in which attackers flood the targets with so much junk traffic that they freeze up.

The outages were intermittent and varied by geography. Users complained they could not reach dozens of internet destinations including Mashable, CNN, the New York Times, the Wall Street Journal, Yelp and some businesses hosted by Amazon.com Inc.

According to Cisco, an American multinational corporation technology company headquartered in California, that designs, manufactures and sells networking equipment worldwide, in this kind of an attack, the hackers build a network of computers that sends the extensive amount of traffic to particular servers so that the use of those servers is denied to other users.

The timings of the attack are crucial as it comes around the time when the US has officially accused Russia of hacking the Democratic National Committee and promised reprisal.