The 'dirtiest' 100 websites have an average of 18,000 threats, with 40 of them each exceeding 20,000, according to security vendor Symantec.
Symantec identified the 'Dirtiest Websites of Summer 2009', as detected by its Norton Safe Web service. The "worst of the worst" sites are plagued mostly by malware, followed by security risks and browser exploits, the company said in a statement on Thursday.
In addition, 75 percent of the dirtiest websites have distributed malware for more than six months.
Nearly half (48 percent) are sites with adult content, but there are also subjects ranging from purchasing electronics to figure skating and deer hunting. Simply visiting such sites — not downloading files or clicking on links — could put a user at risk of system infection; and worse, one's identity, personal and financial information may even land in the hands of cybercriminals, Symantec warned.
Among the blacklisted was aladelnet, a US site found to carry 56,371 threats, including the Downloader Trojan.
Several Chinese sites — qsng.cn, stock888.cn and yt118.com — were included in Symantec's sample list of dirtiest sites.
"This list underscores what our research shows — there has been exponential growth in the number of online threats that are constantly evolving as cybercriminals look for new ways to target your money, identity or assets," Rowan Trollope, Symantec's senior vice president for consumer business, said in the statement. "In 2008, most new infections occurred while people were surfing the web."