The deep Reuters article on the hack:

Vitali Kremez, director of research with New York-based cyber intelligence firm Flashpoint, told Reuters his review indicates that APT 28, a group tied to the GRU, the Russian military intelligence directorate, was behind the leak. He cited similarities with U.S. election hacks that have been previously attributed to that group. 

APT28 last month registered decoy internet addresses to mimic the name of En Marche, which it likely used send tainted emails to hack into the campaign’s computers, Kremez said. Those domains include onedrive-en-marche.fr and mail-en-marche.fr.

"If indeed driven by Moscow, this leak appears to be a significant escalation over the previous Russian operations aimed at the U.S. presidential election, expanding the approach and scope of effort from simple espionage efforts towards more direct attempts to sway the outcome," Kremez said.

Added to the evidence that the GRU-connected hackers are also falsifying documents, it will be interesting to see how they escalate these operations against Merkel in the German election, given that she is turning out to be Putin's new Bête Noire. Bizarre that Russia still faces no repercussions for these actions. Are Trump and Tillerson really so deep in Putin's pocket that they are fighting any suggestion of counter-measures?