Russian hackers have accessed the system of Ukrainian telecommunications company Kyivstar at least since May last year, in a cyberattack that should serve as a warning to the West, the chief of the Ukrainian cyber counter-espionage agency said.

The cyberattack, one of the most impactful since the Russian invasion nearly two years ago, has since December 12 knocked out services provided by Ukraine’s largest telecommunications company to some 24 million users.

In an interview, Ilya Vityuk, head of the Cybersecurity Department of the Security Service of Ukraine (SBU), revealed exclusive details about the attack, which he said was devastating and aimed at inflicting a psychological blow as well as gathering intelligence.

The attack wiped out almost everything, including thousands of servers and PCs, he said, describing it as possibly the first example of a catastrophic cyberattack, which completely destroyed the core of the telecommunications company.

During the investigation, the SBU found that hackers had probably tried to penetrate Kyivstar in March or even earlier. The SBU estimates that the hackers, with the level of access they gained, were potentially able to steal personal information, detect phone locations, intercept SMS messages, and perhaps hijack accounts on the Telegram platform.

A Kyivstar spokesperson said that the company is working closely with the SBU to investigate the attack and will take all necessary measures to eliminate potential future risks.

Vityuk said that the SBU helped Kyivstar restore its systems within days and fend off new cyberattacks. Kyivstar is the largest of Ukraine’s three main telecommunications companies and about 1.1 million Ukrainians live in small towns and villages where no other telecommunications companies operate, Vityuk said.

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