It is now possible for computer hackers to deliver viruses through advertisements on the Web. In fact, web-based ads have become the vehicle of choice among malicious hackers. They are exploiting security holes in the online-ad chain and putting viruses into the advertisements themselves. If a user simply visits a site that shows an infected advertisement, that user's computer could be infected as well. In May 2007, a virus in a banner advertisement automatically took visitors to a website that downloaded malware onto their computers. One of the first security companies to discover the virus, ScanSafe Inc., estimated that the infected ad was on the site for at least 24 hours before it was found, and it infected between 50,000 and 100,000 computers before it was removed. It can also be potentially dangerous to click on advertisements that appear in the sponsored-link portion of search engine pages. In May 2007, McAfee Inc., a web security firm, found that 6.9 percent of sponsored links led to suspicious sites that could download malware onto a visitor's computer. Scott Howe, president of Drive Performance Media, an Internet advertising network, say that the inability to offer a safe haven could present an obstacle between reputable advertisers and their revenues. It represents the biggest fear among advertisers. A brand can be destroyed quickly by an infected advertisement, if advertisers are not careful.