Cybercrimininals are exploiting fears of Tamiflu shortages to lure people into giving them sensitive personal information through fraudulent websites.
Underground web affiliates have formed networks aimed at profiting from fraudulent Tamiflu sales that are also designed to harvest information to be used in other crimes, according to a study published by Sophos.
Thousands of affiliates use spam, adware and malware to drive traffic to their partners' fake pharmaceutical stores, the report said.
These affiliates are able to earn up to $16,000 a day or $5.8m a year promoting pharmaceutical websites, researchers have found.
The UK is among the top five countries purchasing Tamiflu and other drugs from these sites and thus unwittingly assisting additional criminal activity.
Sophos expects concerns about swine flu will drive an even greater volume of traffic and sales through these criminal websites.
"The worrying trend of stockpiling Tamiflu has already been seen in Britain," said Graham Cluley, senior technology consultant at Sophos.
In July, when concerns that global Tamiflu production were falling behind schedule, there was a 1,400% increase in UK internet searches for Tamiflu.
"As more and more cases of swine flu in the UK come to light, it is essential that we all resist the panic-induced temptation to purchase Tamiflu online," said Cluley.
Anyone who thinks they need medication should consult their local health authorities and stay away from quacks on the internet, he said.