Hackers have seeded LinkedIn, the business networking service, with bogus celebrity profiles that link to malicious sites serving up attack code, a security researcher said Wednesday.

Unlike Twitter, which had nearly three-dozen legitimate accounts hijacked Monday, LinkedIn was not compromised. Instead, criminals used the service to create phony profiles, gave them celebrities' names and slapped on the word "nude" to further entice users. Among the names: singer Beyonce and actresses Christina Ricci, Kirsten Dunst and Kate Hudson.

The identical profiles all sported links to sites that promised nude photographs of the celebrities, said Paul Ferguson, a threat researcher at security vendor Trend Micro. Users who clicked on those sites were shunted to malicious sites hosting malware.

"They're using the same mechanism as have earlier e-mail spam campaigns, telling users that they have to install a [video] codec," said Ferguson. The codec is nothing of the sort, but actually a disguised Trojan horse. "They're just casting a wider net using LinkedIn," he said.

LinkedIn reacted quickly, according to Ferguson, who said that the fake accounts first appeared on the site Tuesday. "Once they were notified, they quickly took them down. There's only a handful left when I last looked."

Rival security firm McAfee Inc. said yesterday that it had spotted "several hundred" bogus LinkedIn accounts.

The recent criminal activity on social-style sites -- Twitter was targeted with a first-ever major phishing campaign last week, for example -- will only get worse, Ferguson predicted.

"[Cybercriminals are] just trying to get more eyeballs on their handiwork," he said, explaining why they are turning to social networks such as LinkedIn and Facebook, as well as the micro-blogging Twitter service. "There's a blackhat SEO [search engine optimization] element here, too, since sites like LinkedIn and Facebook often float to the top of search engine results."

McAfee, in fact, came to its count of fake LinkedIn accounts simply by searching Google.

There's not a lot security software can do for users who keep clicking on links that more than likely lead to malware, Ferguson acknowledged. "There's always going to be that social engineering aspect," he said. "People should know by now not to click on links that promise nude pictures."

LinkedIn did not immediately respond to questions about the fake accounts, and what it plans to do to prevent a recurrence.