Yandex suffers data breach after sysadmin sold access to user emails

Russian internet and search company Yandex announced today that one of its system administrators had enabled unauthorized access to thousands of user mailboxes.

The company discovered the breach internally, during a routine check of its security team. The investigation revealed that the employee’s actions led to the compromise of almost 5,000 Yandex email inboxes.

Sysadmin's side business

The employee was a system administrator who had access rights to provide technical support for Yandex’s email service. In a press release today, the company said that the administrator did it “for personal gain,” suggesting that they had a financial motivation.

It is unclear when the employee started to offer unauthorized access to third parties but the total number of inboxes compromised this way amounts to 4,887.

BleepingComputer emailed Yandex for more details about the incident but received no reply at publishing time.

“Yandex’s security team has already blocked unauthorized access to the compromised mailboxes,” the company says, adding that the owners have already been alerted of the breach and that they need to change their account passwords.

As a result of the incident, Yandex will make changes to the administrative access procedure to increase the security of user data. According to the company, payment details have not been impacted.

While this data breach deserves serious scrutiny, Yandex faced a graver threat in the past, when Western intelligence agencies compromised their systems with Regin malware.

The attack happened between October and November 2018, and it targeted technical information regarding user account authentication, Reuters learned at the time.

Yandex acknowledged the attack and said that it was detected and neutralized before it caused any damage.