FILE PHOTO: A woman walks past a store of Ukraine's telecommunications company Kyivstar, amid Russia's attack on Ukraine, in Kyiv, Ukraine December 12, 2023. REUTERS/Alina Smutko/File Photo
LONDON (Reuters) - Russian hackers were inside Ukrainian telecoms giant Kyivstar's system from at least May last year in a cyberattack that should serve as a "big warning" to the West, Ukraine's cyber spy chief told Reuters.
The hack, one of the most dramatic since Russia's full-scale invasion nearly two years ago, knocked out services provided by Ukraine's biggest telecoms operator for some 24 million users for days from Dec. 12.
