The FBI learned North Korea was responsible for last year's cyber-attack on Sony Pictures within a month after the case was first reported, a senior agency official said Tuesday, rejecting allegations that it could be an act by insiders.
"We were absolutely positive in a very short period of time" that the North Korean government was behind the attack, Joseph Demarest, assistant director of the FBI's cyber crime division, was quoted as saying at a briefing, according to news reports.