Yahoo! ‘s ad network is still being used to spread ransomware to Windows PCs a year after the last big outbreak. Adverts served on the Yahoo! homepage as well as the Yahoo! News, Sports, Celebrity, Finance, and Games websites, led to sites hosting malicious code that infected vulnerable systems, according to Malwarebytes. Attacked machines were injected with adware or the infamous CryptoWall ransomware, we’re told.