The malware, which affected only some readers of NYTimes.com, was the result of an “unauthorized advertisement” that made its way onto the newspaper's ad stream, the paper said in a statement on its website Sunday.
“This isn't particular to NYTimes.com, and the method of injection is common enough that it could have happened on dozens of large websites,” Davis told SCMagazineUS.com in an email Monday.
Readers who encountered the malware saw a Windows-like popup that falsely warned them that their computer was infected, Graham Cluley, senior technology consultant at security vendor Sophos, told SCMagazineUS.com in an email Monday.
In typical rogue anti-virus fashion, the malware caused the user's browser to open a screen that appeared to be a Windows “system scan,” during which progress bars and a list of malware that was supposedly being found were displayed.
“The Times believes it has eliminated these ads,” technology writer Riva Richmond said in a Times' Gadgetwise blog post on Monday.
Cluley said the poisoned ads no longer are being served to readers.
According to reports, the Times uses a third-party ad network vendor to manage the delivery of ads on its site. A spokesperson for the newspaper could not be reached Monday for comment.
Cluley said that he thinks the Times' ad vendor is to blame for the incident.
“I think it's fair for them [the paper] to expect that the third-party network will be taking the appropriate steps to ensure that the content they are delivering is not polluted -- just as you would not expect water from your water company to be contaminated," he said.
One Times reader named "Chris," in a comment to Richmond's blog post, questioned fully relying on third-party ad networks.
"Wow, talk about absolving yourself of the blame," Chris wrote. "A site that attracts millions of visitors a day should no doubt be screening its own ads."
Seven Scale's Davis said that placing less trust in third-party content might be the answer to avoiding this problem in the future.
Other news outlets previously have fallen victim to similar attacks, including the website of The Daily Mail newspaper, which served up malicious ads for rogue anti-virus in December 2008, Cluley said.
Newsweek also has been hit with malicious banner ads.