Cops Could Undermine Dark Web Markets by Leaving Fake Reviews

Although law enforcement has had some success in shutting down dark web marketplaces, the sites continue to be fairly resilient, with new sites popping up when others are taken down. With that in mind, researchers have thought of a different way to undermine the dark web markets: the suggest that law enforcement agencies (LEAs) could attempt to lower the value of drugs traded on the marketplaces by purchasing products and then leaving bad reviews.

"By using a game-theoretic model, we find that it is indeed possible for LEAs to use manipulation of customer reviews in order to attack DNM [dark net market] operations," researchers from the University of Cyprus and Boston University write in a paper. The research was presented at the 2015 INFORMS Conference on Information Systems and Technology, which took place in Philadelphia between October 31 and November 1.

Reviews and rating systems are a staple of dark web marketplaces. When a customer purchases an item—be that a bag of cannabis, a rock of MDMA, or anything else—they are often made to leave a numbered rating and piece of feedback about the transaction.

For example, on one listing for a gram of "84% pure MDMA" on popular marketplace AlphaBay, reviewers have written that the vendor is offering the "best product around here," and that it is "good stuff." Customers also comment on the speed of the delivery ("fast shipping") and the standard of the packaging designed to smuggle it through the postal service ("really stealth").

These reviews are the main mechanism for building trust between a vendor and his buyers: a vendor with a generally high rating is probably going to pull in more business than someone who has poor reviews, much like on legal shopping sites such as Amazon or eBay.

The researchers think LEAs could damage that trust by making controlled purchases of a vendor's items and then purposefully leaving negative feedback.

"The LEA's strategy would be to always give bad reviews, but more so when the product quality is high," the researchers write. "In other words, the LEA would deflate the ratings of high quality sellers, more so than the ratings of low quality sellers," for maximum impact.

"By manipulating buyer reviews, the LEA destroys the informativeness of the review signal and makes it less reliable," the paper describes—perhaps leading the buyer to shop with another dealer. Ultimately, some sellers "would see their revenues reduce."

There are a few caveats. Naturally, when police purchase drugs as part of an operation, the dealer is still getting paid, so finding that sweet spot between providing the vendor with business and leaving enough reviews to make any meaningful change would be a challenge. Indeed, one drug vendor on AlphaBay has received 800 pieces of positive feedback in the last 12 months. To reiterate, the research is only theoretical: the paper didn't involve carrying out these attacks in the wild.

This isn't the first time that researchers have targeted the reputation system of illegal markets. In another recent paper, published in the book Disrupting Criminal Networks: Network Analysis in Crime Prevention, researchers from the University of Lausanne and the University of Montreal wrote about discrediting vendors who sell stolen data.

"Trust systems are carders' catch-22: the very same systems that protect them from peers actually expose them to LEAs," they write.

The UK's National Crime Agency wouldn't comment on whether it would deploy such tactics. A spokesperson told Motherboard in an email that, "The NCA doesn't confirm or deny the specific techniques it uses for reasons of operational security. We deploy a wide array of tools to pursue and disrupt serious organised criminals networks and frequently review practices and techniques which best enable us to effectively achieve this."

It is clear that, despite significant efforts for law enforcement to shut them down, the dark web marketplaces are not going away; many continue to be part of a multi-million-dollar-a-day industry. But minimizing the amount of cash the big dealers can make could be another approach to add to the cops' arsenal.