Yesterday, a number of users encountered warnings indicating that an ad provider we use was attempting to load malware on their computers. These warnings were triggered because the ad network was listed as suspicious by Google Safe Browsing. When Google lists a site, it causes certain browsers (especially Chrome) to show a big red warning message that the site is trying to load malware.
While we do have reports from users of Chrome, Firefox, or Kaspersky Antivirus that some ads were trying to load content from a potentially unscrupulous source, we have no reports of actual virus infection. For this reason, we believe that very few, if any, users were actually exposed to malware.
Upon receiving the first reports of these problems, our "Bad Ad Find and Remove" process was triggered and automatically paged our head of ad operations and me. He and I were able to find and quickly remove the ad network from most of the site. Due to caching, Monobook users may continue to see warnings for a little longer. Monaco users should no longer see warnings for this event.
Malware in advertising is a growing problem that we take very seriously. We do background checks on any advertiser who purchases ads with us directly and we only deal with ad networks we believe are trustworthy. Unfortunately, problems occasionally slip through the filters that are in place.
We are sorry that some users encountered malware warnings (and possibly actual malware) while browsing Wikia. We are working hard to improve our ability to detect and prevent these problems entirely.
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