We get asked often where malware comes from when it infects PCs. The answer is 'almost everywhere' – but one source that many people don't realize is web ads. Ads designed to look like download buttons or action buttons on the site they're served on will take you elsewhere and they'll attempt to get you to run a malicious program or script. The best way to avoid this? Run an ad-block program like uBlock. However, many web sites rely on advertising revenue to survive, so if you do ad-block, whitelist sites you visit often as the ad-blocker has a 'malware' blacklist that will still block many dangerous ads.