According to the US firm, a criminal using the alias 'Mastermind' had posted news of the apparent hack, fifty percent of which were of Russian citizens and 40 percent from the EU. Seven million logins were Hotmail accounts, 2.5 million were from Yahoo and 2.3 million were from Gmail.
If the claim is verified, it will have happened behind the backs of the site's owners which later released a statement saying that it did not "have any proven information that any data was stolen from Topface."
"We have a sophisticated security system and will investigate whether we were hacked or not," was a far as the Russian firm was prepared to go.
The statement from Topface explained that the site used a single sign-on form of authentication, a design that in principle reduces the effect of precisely this kind of hack on websites and users because it bypasses passwords.
"Almost all our users use Facebook and other social networks authorisation to access Topface and we have no access to their passwords or any secure data," which means that what's been breached in this attack will at worst have been user email addresses.
Attackers won't therefore have much to attack directly unless they try a brute forcing on some of those email accounts. What they will have is a spam database, which is where its monetary value will lie. They will also have the names of users in some cases.
Topface said it was confident that users wouldn't have "any problems even if any data was stolen from our service," a complacent analysis after a possible data breach on this scale. Any breach of this type asks serious questions about security.
Topface claims to have more than 91.5 million users. So far it doesn't appear to have informed any of them of the breach beyond putting out the web statement.
In 2012, passwords for 1.5 million users of dating site eHarmony appeared on a Russian crime forum.
This story, "'Mastermind' hacker steals 20 million credentials from dating website" was originally published by Techworld.com.