Cybercriminals latch onto a popular search term, such as "Miss Universe 2010," and create false search results that link to infected sites.
SEO poisoning isn't new, but it is a growing problem for small businesses, according to Banerjee.
It begins with hackers isolating keywords that are generating buzz on Google and other search engines. They then create malicious URLs about this topic so that search engines will index it alongside other results.
Suppose thousands of people are Googling "Miley Cyrus." In this attack, cybercriminals would create dummy websites about her that are loaded with malware.
If you're searching for Miley and unwittingly click on one of these links, the malware could be used to hack into your computer or install spyware, Banerjee said.
There's another risk to small businesses. Because SEO poisoning floods search results with bad links, it could push legitimate results down.
"Suppose you sell Miley Cyrus T-shirts online and you're expecting an uptick in business when "Miley Cyrus" is a hot search trend," said Banerjee. "But with so many bad results that come up, people might not even get to [your] link."