Cant understand how the virus got on their unless the systems were not kept up to date?
You cant?
Being up-to-date is not a 100% solution for complete cyber security.
Its just one of the most important steps.
That vulnerability was there since version X was released , some time later the vendors realised that and issued patch Y
All of the time datediff( x, y ) the system was up to date and yet still vulnerable to this attack.
Biting the hand that feeds IT
