Not public AFAIK. But multiple news agencies cite US officials who make the claim it was Cozy Bear / APT29 [1]. Microsoft claims [2], "We believe this is nati

Not public AFAIK. But multiple news agencies cite US officials who make the claim it was Cozy Bear / APT29 [1]. Microsoft claims [2], "We believe this is nation-state activity at significant scale ... Because of the sophistication of the techniques and operational security capabilities of the actor, we want to encourage greater scrutiny by the broader community..." [1] https://en.wikipedia.org/wiki/Cozy_Bear https://en.wikipedia.org/wiki/Cozy_Bear [2] https://blogs.microsoft.com/on-the-issues/2020/12/13/customers-protect-nation-state-cyberattacks/ https://blogs.microsoft.com/on-the-issues/2020/12/13/custome...