Over the past few weeks, three of the longest running and most venerated Russian-language online forums serving thousands of experienced cybercriminals have been hacked. In two of the intrusions, the attackers made off with the forums’ user databases, including email and Internet addresses and hashed passwords.

On Tuesday, someone dumped thousands of usernames, email addresses and obfuscated passwords on the dark web apparently pilfered from Mazafaka (a.k.a. “Maza,” “MFclub“), an exclusive crime forum that has for more than a decade played host to some of the most experienced and infamous Russian cyberthieves.

At the top of a 35-page PDF leaked online is a private encryption key allegedly used by Maza administrators. The database also includes ICQ numbers for many users. ICQ, also known as “I seek you,” was an instant message platform trusted by countless early denizens of these older crime forums before its use fell out of fashion in favor of more private networks, such as Jabber and Telegram.

This is notable because ICQ numbers tied to specific accounts often are a reliable data point that security researchers can use to connect multiple accounts to the same user across many forums and different nicknames over time.

Cyber intelligence firm Intel 471 assesses that the leaked Maza database is legitimate, and that the file includes more than 3,000 rows containing usernames, partially obfuscated password hashes, email addresses and other contact details.

“The file comprised more than 3,000 rows, containing usernames, partially obfuscated password hashes, email addresses and other contact details,” Intel 471 found, noting that Maza forum visitors are now redirected to a breach announcement page. “Initial analysis of the leaked data pointed to its probable authenticity, as at least a portion of the leaked user records correlated with our own data holdings.”

The attack on Maza comes just weeks after another major Russian crime forum got plundered. On Jan. 20, a longtime administrator of the Russian language forum Verified disclosed that the community’s domain registrar had been hacked, and that the site’s domain was redirected to an Internet server the attackers controlled.

“Our [bitcoin] wallet has been cracked. Luckily, we did not keep large amounts in it, but this is an unpleasant incident anyway. Once the circumstances became clear, the admin assumed that THEORETICALLY, all the forum’s accounts could have been compromised (the probability is low, but it is there). In our business, it’s better to play safe. So, we’ve decided to reset everyone’s codes. This is not a big deal. Simply write them down and use them from now on.”

A short time later, the administrator updated his post, saying:

“We are getting messages that the forum’s databases were filched after all when the forum was hacked. Everyone’s account passwords were forcibly reset. Pass this information to people you know. The forum was hacked through the domain registrar. The registrar was hacked first, then domain name servers were changed, and traffic was sniffed.”

On Feb. 15, the administrator posted a message purportedly sent on behalf of the intruders, who claimed they hacked Verified’s domain registrar between Jan. 16 and 20.

“It should be clear by now that the forum administration did not do an acceptable job with the security of this whole thing,” the attacker explained. “Most likely just out of laziness or incompetence, they gave up the whole thing. But the main surprise for us was that they saved all the user data, including cookies, referrers, ip addresses of the first registrations, login analytics, and everything else.”

The compromise of Maza and Verified — and possibly a third major forum — has many community members concerned that their real-life identities could be exposed. Exploit — perhaps the next-largest and most popular Russian forum after Verified, also experienced an apparent compromise this week.

According to Intel 471, on March 1, 2021, the administrator of the Exploit cybercrime forum claimed that a proxy server the forum used for protection from distributed denial-of-service (DDoS) attacks might have been compromised by an unknown party. The administrator stated that on Feb. 27, 2021, a monitoring system detected unauthorized secure shell access to the server and an attempt to dump network traffic.

Some forum lurkers have speculated that these recent compromises feel like the work of some government spy agency.

“Only intelligence services or people who know where the servers are located can pull off things like that,” mused one mainstay of Exploit. “Three forums in one month is just weird. I don’t think those were regular hackers. Someone is purposefully ruining forums.”

Others are wondering aloud which forum will fall next, and bemoaning the loss of trust among users that could be bad for business.

“Perhaps they work according to the following logic,” wrote one Exploit user. “There will be no forums, there will be no trust between everyone, less cooperation, more difficult to find partners – fewer attacks.”