Hackers have managed to steal millions of user accounts from several Mail.Ru domains, but the Russian Internet company says the compromised credentials are invalid and assured customers that they are not at risk.
LeakedSource, a service that allows users and businesses to check if their online accounts have been compromised, reported on Wednesday that cybercriminals obtained roughly 25 million username and password combinations from three different domains: cifre.mail.ru, parapa.mail.ru and tanks.mail.ru. The affected domains host forums for games acquired by the Mail.Ru Group over the past years.
The passwords were stored as MD5 hashes with and without salts, which has allowed LeakedSource to easily crack millions of them. The most common passwords appear to be 123456789, 12345678, 123456 and 1234567890.
While this might sound like a serious breach, Mail.Ru says the leaked passwords are no longer valid and its forums now use a different authorization system. The company also pointed out that the compromised passwords were never associated with Mail.Ru email accounts or other services.
Nevertheless, the many password reuse attacks detected recently by companies such as Facebook, GitHub, Reddit and Netflix show that even older credentials can be useful for malicious actors.
The Mail.Ru forums were reportedly breached in August after attackers exploited a vulnerability in the vBulletin forum software. vBulletin flaws have been leveraged over the past few weeks to breach numerous websites, including Epic Games and Dota 2 forums.
In May, Hold Security reported identifying 272 million email credentials obtained by cybercriminals after breaching the systems of several companies. Researchers discovered that 57 million of the credentials were for Mail.ru accounts, but the Internet company later determined that 99 percent of the usernames and passwords were invalid.
LeakedSource says it has collected more than 2 billion leaked records to date, and it claims to possess more data that has yet to be added to its databases. In comparison, the Have I Been Pwned service operated by security expert Troy Hunt has more than 1.3 billion accounts collected from 125 breached websites.
Over the past months, LeakedSource disclosed several breaches, including ones impacting SocialBlade (300,000 accounts), VerticalScope (45 million), VK (100 million), Myspace (360 million) and Tumblr (65 million).