A “massive” cyber attack which shut down the websites of several US government agencies could be linked to a similar outage in South Korea.
The Treasury Department, Secret Service, Federal Trade Commission and Transportation Department sites were all down at various points over the weekend and into this week, officials said.
Some of the sites were still experiencing problems on Tuesday evening after the attack, which started on July 4.
The agencies, including some which are responsible for fighting cyber crime, were working with their internet service provider to resolve the problem, the officials added.
Government agencies and banks in South Korea also had their websites paralysed by a suspected cyber attack on Tuesday, with some still unstable or inaccessible yet.
The problems in the two countries appeared to be linked, said Ahn Jeong-eun, a spokeswoman at the Korea Information Security Agency.
The US sites experienced a “massive outage”, according to Keynote Systems, a company which monitors 40 government sites in America.
Ben Rushlo, director of internet technologies at the firm, said of the transportation department site problems: “This is very strange. You don’t see this.
“Having something 100% down for a 24-hour-plus period is a pretty significant event.”
He added: “The fact that it lasted for so long and that it was so significant in its ability to bring the site down says something about the site’s ability to fend off (an attack) or about the severity of the attack.”
A computer emergency team from the Homeland Security Department has issued a notice to federal departments about the problems, spokeswoman Amy Kudwa said.
The message advised agencies “of steps to take to help mitigate against such attacks”.
Networks in the US are targeted every day and measures have been put in place to minimise the impact on federal government websites, Ms Kudwa added.
SKY