Using messages designed to exploit worries about the swine flu outbreak -- a technique known as social engineering -- spammers are trying to infect computers, steal information, and drive online pharmacy sales.

Symantec on Tuesday reported that spam messages with provocative titles like "Salma Hayek caught swine flu!" and "US swine flu fears" are being widely distributed.

"The [swine flu] scare has spawned a spamming frenzy, like sharks smelling blood in the water," Symantec researcher Mayur Kulkarni said in a blog post.

Some of these messages contain no malware or malicious links and appear to be information harvesting campaigns. But US-CERT, a computer security group operated in conjunction with the U.S. Department of Homeland Security, on Tuesday warned that spam messages may contain links to phishing or malware sites, or malicious attachments. It's encouraging Internet users to rely on the Centers for Disease Control Web site for information about the swine flu.

Marshal8e6, an e-mail security company, also said that it has seen flu-themed spam seasoned with celebrity references. It reports receiving spam containing links to online pharmacy sites sent by the Rustock botnet.

Trend Micro security researcher Adrian Labiano observes that spammers are using flu-themed subject lines because references to current events produce better results. "Spammers are using this social engineering technique because having the latest news as the mail's subject greatly increases the chance that the recipient will open their spammed messages," he explained in a blog post.

Another security company, F-Secure, finds that the swine flu outbreak has prompted a surge of Internet domain registrations related to the swine flu. The company has posted a list of 278 such domains. Most of them will probably be used in conjunction with spam campaigns or other dubious efforts to profit from the outbreak.

McAfee Avert Labs, which also has reported celebrity-themed swine flu spam, said that Internet domain registrations mentioning the word "swine" are up by factor of 30.

Cisco's IronPort anti-spam service said swine flu spam has accounted for as much as 4% of global spam recently.

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