Anonymous, which briefly knocked the FBI and Justice Department websites offline in retaliation for the US shutdown of file-sharing site Megaupload, is a shadowy group of international hackers with no central hierarchy.
Blog publishing platform WordPress was running normally on Sunday after suffering cyber attacks suspected to have originated in China.
Lithuania's central bank said Friday it had been hit by a cyber-attack, but had eventually overcome the assault on its website and other online services.
US Federal Bureau of Investigation agents carried out a raid on the home of an Ohio man suspected of being a member of the Lulz Security hacker group, The Wall Street Journal reported Thursday.
A 24-year-old man allegedly linked to the Anonymous "hacktivist" group was arrested Tuesday over a cyber attack on a website run by the frontman of heavy rock group Kiss, the FBI said.
British police working with the FBI arrested a 19-year-old man over attacks by a hacker group on businesses and government agencies including the CIA, US Senate and Sony, Scotland Yard said Tuesday.
The website of the Central Intelligence Agency was briefly inaccessible on Friday after the hacker group Anonymous claimed to have knocked it offline.
The National Security Agency's website went down Friday and the US spy service known for hacking into computer networks said it was investigating the outage, a spokesperson said.
A British teenager accused of attacking websites as part of an international hacking group was remanded in custody at a court Saturday, despite being diagnosed with autism.