Spam may be synonymous with male enhancement drugs, but new research shows that Americans are far more likely than buyers in other countries to turn to spam-advertised pharmacies to obtain pills to treat serious ailments—a trend that reflects differences in government health care and prescription drug policies.

Researchers at the University of California, San Diego, have collected the first data showing which drugs consumers most often buy from spam advertisements, and how much they spend at shadowy online apothecaries.

“People are going to them when they’re either too embarrassed to talk to a doctor, or when it would be far too expensive to buy these drugs otherwise,” said Chris Kanich, a PhD candidate at UCSD’s computer science department, and lead researcher of the study.

Previous estimates of monthly worldwide revenue from spam have varied dramatically, from $300,000 to more than $58 million. The UCSD researchers found that the largest rogue Internet pharmacies generate between $1 million and $2.5 million in sales each month, although they caution that their estimates are conservative.

Kanich says the figures show that although the spam-advertised market is substantial, it is not nearly as big as some have claimed, and falls short of annual expenditures on technical anti-spam solutions by corporations and ISPs.

“We were trying to make a lowball estimate,” Kanich said. “A lot of previous estimates have been from people who are making rough estimates and have incentives to push the numbers one way or another.”

The researchers arrived at their dollar estimates by mining transaction data from seven of the top spam-advertised pharmacies. By making targeted “buys” from each pharmacy brand, they discovered that each of the pharmacy assigns sequential order numbers to individual purchases. Thus, from any pair of purchases, the UCSD team could determine the total transaction volume for the interval between their two purchases by subtracting the first order number from the second.

To learn which products customers bought from spam-advertised pharmacies, the researchers exploited a hidden feature in the websites used to promote the largest organization in the industry—EvaPharmacy. They discovered that two-thirds of EvaPharmacy affiliate Web sites “outsourced” the hosting of images to compromised third-party servers.

The researchers contacted the victim of one infection, who shared Web traffic log data from the compromised machine. The log data from the compromised machine also recorded visitors’ Internet addresses; that discovery revealed the number of unique visitors and the country of origin of each customer.

The UCSD team found that after visitors selected a particular drug from the pharmacy’s home page, they were sent to a product page, where they were prompted to select the particular dosage and quantity. After that, users were sent to a shopping cart page, which included many new
images representing product recommendations. By comparing the number of cart visits with distinct Internet addresses, they were able to estimate the fraction of visitors who selected an item from the shopping cart images, and were able to infer the product each customer selected.

The researchers found significant differences between the drug selection habits of Americans and customers from Canada and Western Europe. The analysis divided the EvaPharmacy pills into two broad categories: lifestyle drugs such as erectile dysfunction and human growth hormone pills, and non-lifestyle drugs, including those used to treat disorders including anxiety, sinus infections, high blood pressure, hair loss, cancer, and infertility.

The researchers discovered that U.S. customers selected non-lifestyle items 33 percent of the time. In contrast, Canadian and Western-European customers almost always bought drugs in the lifestyle category—only 8 percent of the items placed in their shopping carts were non-lifestyle items.

“We surmise that this discrepancy may arise due to differences in health-care regimes; drugs easily justified to a physician may be fully covered under state health plans in Canada and Western Europe, leaving an external market only for lifestyle products,” the researchers
write. “Conversely, a subset of uninsured or underinsured customers in the U.S. may view spam-advertised, no-prescription-required pharmacies as a competitive market for meeting their medical needs. To further underscore this point, we observe that 85 percent of all non-lifestyle drugs are selected by U.S. visitors.”

Unlike many other nations, the United States has not enacted price controls on prescription medications. According to a study last year by the AARP, prescription drug prices in the United States rose more than 8 percent in 2009; some drug prices have increased between 40 and
92 percent in the past five years.