In the middle of the week, the amount of spam referencing the virus outbreak made up about four percent of all unwanted email, said Scott Olechowski, manager of Cisco's threat research team. However, those amounts fell Friday to roughly one percent.
"The feeling is that swine flu itself is such an easy thing for spam filters to catch," he told SCMagazineUS.com on Friday.
To keep their ploy going, some spammers have opted for targeting non-English speaking recipients, such as people living in Portugal and Japan, where they may not have controls yet in place to weed out swine flu spam, Olechowski said.
Up until recently, most of the swine spam was trying to get recipients to purchase pharmaceuticals, in some cases medications they claimed can help prevent infection, he said. But many of the current emails are trying to load malware onto users' computers by trying to get them to click on a link.
In most cases, victims are then delivered to a website that tries to persuade them to install a trojan disguised as a codec, Olechowski said. In some cases, though, users can be infected simply by visiting the malicious site if their systems are unpatched.
Security firm SonicWALL, meanwhile, said Friday that its researchers have detected a swine flu-related malware scam targeting Mexican banks.
Should the outbreak continue to make big news, spammers likely will customize their messages so they still are related to swine flu but do not actually use those specific words, Olechowski said.