Pavel Durov, founder of the Russian social network VKontakte, was home alone in his apartment in St. Petersburg on a weekend when a contingent of men in camouflage uniforms knocked violently on his door.
PALO ALTO, Calif. — In late 2013, an A.T.M. in Kiev started dispensing cash at seemingly random times of day. No one had put in a card or touched a button. Cameras showed that the piles of money had been swept up by customers who appeared lucky to be there at the right moment.