What with its high level of anonymity, the secure Tor network has a well earned reputation for being the web’s favorite hangout for drug dealers, porn kings, botnets and other ne’er-do-wells. “But, but, but… it’s still the best way to mask your browsing activity!” you scream, given what we know about the NSA. That may be so, but first impressions often count, and that’s certainly true with Tor.

Apparently, all the bad stuff you’ve heard about Tor is true – the network is overrun with pornography, botnets and illegal narcotics, and most especially the latter. At least, it is according to a group of Luxembourg researchers who recently came across an exploit that made the anonymous network not-quite-so-anonymous any more. The vulnerability allowed Alex Biryukov, Ivan Pustogarov and Ralf-Philipp Weinmann at the University of Luxembourg to pull data from more than 39,000 Tor users, before they reported it to the Tor Project, which has since issued a patch. However, the researchers still kept a hold of the data that they pulled – which helped them to identify the most popular websites being browsed by Tor – and they’ve now published their interesting findings.

As MIT Technology Review explains, botnets and porn sites (including many illegal ones) account for the vast majority of traffic on Tor. Indeed, out of the top twenty most popular Tor addresses, eleven belonged to botnets, while five were from porn sites. Aside from these, the researchers noted that much of the traffic came from Bitcoin mining sites, as well as the web’s most infamous black marketplace, the Silk Road.

In other words, there’s a lot of bad stuff going on behind the scenes with Tor, but that doesn’t mean that do-gooders should stop using it. Tor remains by far and away your best bet if you wish to remain anonymous while browsing the web, even if it’s not totally secure at the moment in time.

Nevertheless, these botnets in particular are something to look out for – while for the most part they’ll only slow things down, they can and do cause some serious damage from time to time. And be mindful that certain porn sites and items offered for sale on the Silk Road are indeed illegal, and if you do end up getting caught, you’ll only have yourself to blame ;)