The “ahmia.fi” project census Dark Web websites, aka hidden services, by providing search engine functionalities by indexing the content present on the Tor network. Nurmi noticed an anomalous number of clones of hundreds of other Dark Web sites, including the popular search engine DuckDuckGo and also his ahmia.fi.
“Hi, I noticed a while ago that there is a clone onion site for Ahmia. Now I realized that someone is actually generated similar onion domains to all popular onion sites and is re-writing some of the content. For instance, REAL Ahmia: http://msydqstlz2kzerdg.onion/search/?q=duckduckgo FAKE Ahmia: http://msydqjihosw2fsu3.onion/search/?q=duckduckgo Look carefully and notice the difference: REAL DDG: http://3g2upl4pq6kufc4m.onion/ FAKE DDG: http://3g2up5afx6n5miu4.onion/ It seems that the situation is this: The unknown attacker tries to direct users to these fake sites. The attacker is running multiple onion addresses similar to the popular onion addresses. These sites are actually working as a transparent proxy to real sites. However, the attacker works as MITM and rewrites some content. It is possible that the attacker is gathering information, including user names and passwords. I did some data mining and comparison with Ahmia.fi and seems to be that there are at least 255 fake mirror sites. See the list http://pastebin.com/iHPwhCeH” wrote Nurmi on the Tor-Talk mailing list.
Due to the structure of the onion URL it is quite easy for bad actors to trick Tor users into visiting bogus websites by spreading the fake address of legitimate Dark Web websites. No one will be able to remember an onion URL, let’s consider as an example the DuckDuckGo case:
Nurmi speculates that the fake Dark Web websites aren’t just duplicates of the real sites, but also proxies for them (at least this is the situation verified for his portal) allowing an attacker to run Man-in-the-Middle attacks to steal sensitive data or also inject malicious code that could be used to de-anonymize Tor users.
The user ‘garpamp’ reported that such activity has been “going on for years”, he claims that list .onion addresses being modified by malicious Tor exit nodes. The user garpamp claims to have noticed malicious exit nodes being used to rewrite regular web pages, he confirmed that a bad exit node was actually rewriting the addresses on the pastebin page posted by Nurmi.
“…I’ve also seen exits  rewriting onion addresses found on clearnet.
 Like the ****** behind this piece of **** is doing to that pastebin url… Arag0n 188.8.131.52 dc914d754b27e1a0f196330bec599bc9d640f30c”
Roger Dingledine, Project Leader of Tor developers, confirmed that the bad exit node discovered by garpamp has now been given the BadExit flag. This means that it cannot operate as an exit node.
In time I’m writing, we have no news regarding who is behind the fake sites, who is behind the exit nodes rewriting real onion addresses and their motivation.
(Security Affairs –Dark Web websites, Deep Web)