Overwhelming cyber-attack took out Ukraine’s largest mobile operator – Kyivstar Pres. explains how

“There was unusual network behavior at 5:26. All our focus was on restoring the network, which started to work with major interruptions. This created an incredible number of anomalies in these systems. We thought that this problem comes either from the switching system or transportation network,” said Komarov, noting that the company only later realized the true scale of the problem.

“By 6:30 in the morning, it was understood that this was an overwhelming cyberattack on the network core and infrastructure.  And the issues that started at 5 am were designed to distract our attention, rather than actually bring down the company's radio network,” he said.

“The network core consists of several elements: a virtual network that operates over the physical network, and also IT infrastructure,“ Komarov explained.

“A cascading failure of a large number of infrastructure elements started.”

Kyivstar experienced a massive outage on the morning of Dec. 12., with communication problems observed across Ukraine.

The company announced a technical failure, resulting in the unavailability of communication services and internet access for part of its subscriber base.

The Digital Transformation Ministry explained why the Kyivstar outage caused problems with national roaming. The restoration of communication services for Kyivstar subscribers began within a few hours, said Vice Prime Minister Oleksandr Kubrakov.