Fast-moving cyberattacks wreak havoc worldwide

A fast-moving wave of cyberattacks swept the globe Friday, apparently exploiting a flaw exposed in documents leaked from the US National Security Agency.The attacks -- which experts said affected dozens of countries -- used a technique known as ransomware that locks users' files unless they pay the attackers a designated sum in the virtual currency Bitcoin.Affected by the onslaught were computer networks at hospitals in Britain, Russia's interior ministry, the Spanish telecom giant Telefonica an