Russian hackers are behind a massive cyber attack at Australia’s largest health insurer, Medibank, the Australian Federal Police (AFP) said Friday. Data stolen from Medibank began appearing on the dark web on Wednesday after the company refused to pay a ransom to the hackers. About 9.7 million current and former Medibank customers are believed to have been affected by the October hack. AFP commissioner Reece Kershaw told a media conference the attack was carried out by a Russian group that was “likely responsible” for other significant breaches across the world. The group may have affiliates i…