Symantec reverse engineered one version of the malware, called “Flashback.K,” which it said deprives Google of advertising revenue. Flashback is believed to be the largest-ever malware campaign that has targeted Apple’s operating system. Apple released a special Flashback removal tool on April 13. The company looked at what happened when a user clicked on an ad for toys. The click for the ad, worth $.08, is redirected to the a website affiliated with the attackers.”]