Glenn Greenwald writes instructively on this matter and while in this case he may be unduly cautious, he makes points that are useful considering whether in this case or not the anonymous revelations are accurate. As he notes:
Needless to say, questions about who hacked the DNC and Podesta email accounts are serious and important ones. The answers have widespread implications on many levels. That’s all the more reason these debates should be based on publicly disclosed evidence, not competing, unverifiable anonymous leaks from professional liars inside government agencies, cheered by drooling, lost partisans anxious to embrace whatever claims make them feel good, all conducted without the slightest regard for rational faculties or evidentiary requirements.