Computer attacker still a mystery to US security

WASHINGTON: The top US intelligence official says the United States still has not figured out who was behind the July 4 cyber attacks that took down a series of government Web sites.

Dennis Blair, the national intelligence director, says the attackers covered their tracks by temporarily hijacking a network of computers, which were used to spawn the cyber offensive. The government is working with other countries to identify the perpetrators.

The South Korean government says it has evidence of North Korean involvement but has not yet assigned blame.

The attacks, in which hundreds of computers tried to connect to a single Web site at the same time to overwhelm the server, caused outages on prominent government-run sites in both the United States and South Korea.