Tiervermittlung Deutschland » was quoted as saying

WASHINGTON， Oct. 21 (Xinhua) -- Twitter， PayPal and some other major United States websites were shut down temporarily on Friday as American Internet infrastructure companies Dyn and Amazon were hit by waves of cyber attacks.


Dyn， headquartered in New Hampshire， said in posts on its website that its Domain Name System (DNS) infrastructure suffered three waves of distributed denial of service (DDoS) attacks， which flooded it with traffic from multiple sources to make it inaccessible.


The company said the first wave was a "large" DDoS attack that started at 7:10 a.m. EDT (1110 GMT) and mainly affected the U.S. east coast.


"Dyn's engineers were able to successfully mitigate the attack at approximately 13:20 UTC (1320 GMT)， and shortly after， the attack subsided，" it said.


Compared with the first wave， the second one that started at about 11:50 a.m. EDT (1550 GMT) and lasted until 1:00 p.m. EDT (1700 GMT) was "distributed in a more global fashion，" with affected customers possibly seeing "intermittent resolution issues as well as increased global latency，" according to the company.


At around 4:00 p.m. EDT (2000 GMT)， Dyn reported a third DDoS attack， which it said had been "resolved" a little over two hours later.


Amazon Web Services (AWS)， a unit of Amazon that hosts many of the web's popular destinations including Netflix， also reported an attack that affected people on the U.S. east coast around the same time in the morning.


"Between 4:31 a.m. (1131 GMT) and 6:10 a.m. PDT (1310 GMT)， we experienced errors resolving the DNS hostnames used to access some AWS services in the US-EAST-1 Region，" the company said on its website.


But this issue has been resolved and the service is now operating normally， it noted.


The attacks reportedly kept many users in the United States and parts of Europe from accessing Twitter， PayPal， Reddit， Spotify， Netflix and other sites.


Digital payments company PayPal was one of the companies that admitted experiencing brief service interruptions due to the attacks.


"We're sorry for the inconvenience，" PayPal tweeted.


White House spokesman Josh Earnest said the U.S. Department of Homeland Security is monitoring this situation and will take a close look at it.


"But at this point， I don't have any information to share about who may be responsible for that malicious activity，" Earnest told reporters.


A senior U.S. intelligence official told NBC News their current assessment is that this is "a classic case of internet vandalism."


The official was quoted as saying that it does not appear at this point to be any kind of state-sponsored or directed attacks.


A group called New World Hackers claimed responsibility for the attacks via Twitter， although their claims cannot be independently verified.