Russia's most aggressive ransomware group disappeared. It's unclear who disabled them.
Just days after President Biden demanded that President Vladimir V. Putin of Russia shut down ransomware groups attacking American targets, the most aggressive of the groups suddenly went off-line early Tuesday. The mystery is who made it happen. The group, called REvil, short for “Ransomware evil,” has been identified by U.S. intelligence agencies as responsible for the attack on one of America’s largest beef producers, JBS. Two weeks after Mr. Biden and Mr. Putin met in Geneva last month, REvil took credit for a hack that affected thousands of businesses around the world over the July 4 holiday. That latest attack led to Mr. Biden’s ultimatum in a phone call on Friday to the Russian president. Later, Mr. Biden said that “we expect them to act,” and when asked by a reporter later if he would take down the group’s servers if Mr. Putin did not, the president simply said, “Yes.” He may have done exactly that. But that is only one possible explanation...