Hackers Came, But the French Were Prepared (nytimes.com)
Adam Nossiter, David E. Sanger, and Nicole Perlroth, reporting for the New York Times: Everyone saw the hackers coming. The National Security Agency in Washington picked up the signs. So did Emmanuel Macron's bare-bones technology team. And mindful of what happened in the American presidential campaign, the team created dozens of false email accounts, complete with phony documents, to confuse the attackers (Editor's note: the link could be paywalled; alternative source). The Russians, for their part, were rushed and a bit sloppy, leaving a trail of evidence that was not enough to prove for certain they were working for the government of President Vladimir V. Putin but which strongly suggested they were part of his broader "information warfare" campaign. The story told by American officials, cyberexperts and Mr. Macron's own campaign aides of how a hacking attack intended to disrupt the most consequential election in France in decades ended up a dud was a useful reminder that as effective as cyberattacks can be in disabling Iranian nuclear plants, or Ukrainian power grids, they are no silver bullet. The kind of information warfare favored by Russia can be defeated by early warning and rapid exposure.
So, what is that evidence?
Motivation; ability; ...
That something being the name of an employee of Evrika, a known Kremlin defense contractor.
Now while it's undeniably a possibility that the metadata was planted as part of a 'false-flag' operation, that theory itself lacks both corroborating evidence and plausible motivation (though other actors certainly have the means). Even at the risk of being wrong, reason requires we apply Occam's razor.
Yes, and then there's the public testimony from US intelligence services:
Testifying in front of the Senate Armed Services Committee in Washington on Tuesday, Adm. Michael S. Rogers, the director of the National Security Agency, said American intelligence agencies had seen the attack unfolding, telling their French counterparts, “Look, we’re watching the Russians. --TFA
Look I know what you mean, it's just so damn annoying that the CIA, NSA, DGSE etc, don't run all their classified material past my desk. Don't the know who the HELL I AM?! ... scarily they probably do. :/
Seriously though ... while we're not, and are never likely to be, at the beyond reasonable doubt standard, on the balance of probabilities the publicly available evidence points towards Russian involvement. And that is hardly surprising: the Kremlin explicitly favoured Le Pen and we cannot but expect Russia to deploy its capability in favour of Russian national interest.
You can bank on the fact that in any election anywhere in the world where the Kremlin feels it has an interest in the outcome, Russian aligned hackers and (so called) troll-armies (i.e. social media influencers) will be at work in an attempt to influence the outcome (however marginal that influence may be).
Better to be despised for too anxious apprehensions, than ruined by too confident a security. --Edmund Burke