  Detecting counterfeits on online marketplaces is challenging, and current
methods struggle with the volume of sales on platforms like eBay, while
cryptomarkets openly sell counterfeits. Leveraging information from 453
cryptomarket counterfeits, we automated a search for corresponding products on
eBay, utilizing image and text similarity metrics. We collected data twice over
4-months to analyze changes with an average of 159 eBay products per
cryptomarket item, totaling 134k products. We found identical products, which
would warrant further investigation as to whether they are counterfeits.
Results indicate increasing difficulty finding similar products over time,
moderated by product type and origin. Future improved versions of the current
system could be used to examine possible connections between cryptomarket and
surface web listings more closely and could hold practical value in supporting
the detection of counterfeits on the surface web.
