"According to Kaspersky, the miscreants gained access to the enterprise networks via phishing emails, some of which included organization-specific information that wasn't publicly available."
Kaspersky are Russian. It seems highly unlikely that "Eastern European countries" and "Ukraine" would allowing Russian anti-virus software on their networks, scanning their emails. It also seems very unlikely that Kaspersky would have access to their emails otherwise or be able to confirm "information that wasn't publicly available" for those organizations.
Lots of this story doesn't quite ring true.
Pinch of salt.