Services fully restored after major cyberattack, Kyivstar president says

The carrier has resumed full operations both in Ukraine and abroad. The last service to be launched was international roaming. Kyivstar completed its restoration on Dec. 19.

"All services are working without any restrictions," Komarov said.

A morning outage in some regions of Ukraine was a technical consequence of the Dec. 12 hacker attack on the operator, not a new attack, he said.

Kyivstar, Ukraine's largest operator, experienced a large-scale outage on Dec. 12. Communication problems were observed throughout Ukraine.

The company confirmed the technical failure, which resulted in the unavailability of communication and Internet access services for part of its subscriber base.

Later, Kyivstar stated that the failure was caused by a hacker attack.

Ukraine’s SBU security service has opened a criminal investigation into the cyberattack on the national mobile operator Kyivstar, which may have been carried out by the Russian special services.

Russian hackers from the Solntsepek group eventually claimed full responsibility for the cyberattack on Kyivstar.

Kyivstar issued a statement on Dec. 13 denying rumors that computers and servers had been destroyed, adding that subscribers' personal data had not been compromised.

On the same day, Kyivstar announced the restoration of voice communications and partial restoration of fixed-line internet.

Kyivstar restored access to SMS, mobile data, and Home Internet services by Dec. 18.

Kyivstar reported problems with voice communication and its mobile app in a number of cities in western and southern Ukraine on the morning of Dec. 20. The company later said that it had fixed the problems.