Taking a Tor of the dark web isn’t so anonymous xijian/Getty

Dark web users may not be as anonymous as they think.

There are a high number of potentially privacy-busting connections between the dark web – hidden online networks that require special software to access – and the regular “surface” web, say privacy researchers.

“The dark web is maybe not as dark as it seems,” says Iskander Sanchez-Rola at the University of Deusto, Spain, who led the investigation into the Tor network, a dark web network that uses encryption to conceal users’ identity.


The group found close links between the dark web and surface web. More than 20 per cent of the 1.5 million dark web pages they analysed imported resources like pictures, documents and Javascript files from surface websites.

This raises potential privacy concerns, as owners of these resources can track when they are loaded by a user, giving them a window into the hidden domain. For example, Google could monitor traffic to 13 per cent of the domains in the study’s dataset this way, the researchers say.

Proxy worries

They also found tracking scripts, designed to analyse users’ browsing behaviour, on 27 per cent of the hidden pages they looked at. Nearly a third of these originated from the surface web, and 43 per cent of those were from Google.

That’s a problem, says Sanchez-Rola, because if a dark web service uses the same script as a site on the surface web, anyone using it could start tracking a user’s activity and potentially identify them when they visit less private sites. The researchers will present their work at the World Wide Web Conference in Perth, Australia, next week.

Those using Tor proxies – services on the surface web that act as gateways to the dark web, like the popular Tor2Web – are most at risk. These services can already see users’ IP addresses, but the links between the dark web and surface web mean that third parties could also access that information. If a user opens a dark web page that features a surface web resource through a proxy, their browser fetches this resource in the normal way, bypassing the anonymisation network. Using the Tor Browser to access the dark web offers better privacy protection, says Sanchez-Rola.

It is also better at protecting against web tracking, but only if users switch on script blocking, which can cause sites to malfunction.

“This research has demonstrated for the first time how much of the dark web is intrinsically linked to the surface or clear web,” says security researcher Sarah Jamie Lewis.

Her OnionScan tool, which probes dark web services for vulnerabilities, has found security issues that can de-anonymise up to 35 per cent of dark web servers, but she says there has been little action from site operators. The new research is a “wake-up call” for hosts to stop relying on third-party trackers and scripts that can put both users and themselves at risk, she says.

Read more: Why the dark net is more resilient to attack than the internet