The hacking of the Anglia server was not a problem, it was an easier part. Many groups/individuals could have done it. The issue at hand is how to analyze data in no time. Analysis of thousands of emails was done immediately and it shows that people who were analyzing the contents were experts in the field, not hackers. They found the smoking gun for the fraud right away. It is possible to gather volunteer experts but not in no time. And not in secrecy. The signature is all over the place, someone who is expert in swift analysis of acquired data - i.e industrial espionage. I am sure Putin must have a plausible deniability of all of this.
It really does not matter who did it - the stopping of the fraud is what counts. People behind the fraud are not scammers, they are mass murderers.