You've probably heard of malware-laden ads causing havoc on the web, but rarely on this scale. Malwarebytes has discovered a malware campaign that was using Yahoo's ad network to target legions upon legions of visitors -- Yahoo's main site racks up 6.9 billion visits per month. While it's not clear what would happen if you fell victim to an attack, the Flash-based exploit kit linked to the campaign typically includes both ad fraud and ransomware. In short, there's a real chance that you could have been locked out of your PC simply by checking on your fantasy sports league.
Notice the emphasis on the past tense, though. Yahoo was quick to take this "malvertising" campaign down, so you're not at risk as I write this. Even so, it's not exactly comforting to know that malware writers could even slip their code into such a large ad network. Yahoo's still investigating what happened, but it appears that online ad giants may need stricter filters on what gets through.
[Image credit: AP Photo/Marcio Jose Sanchez]