Did CrowdStrike have proof that Russia hacked the DNC?
Yes, and this is also supported by the U.S. Intelligence community and independent Congressional reports.
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This conclusion has most recently been supported by the Senate Intelligence Committee in April 2020 issuing a report [intelligence.senate.gov] validating the previous conclusions of the Intelligence community, published on January 6, 2017, that Russia was behind the DNC data breach.
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It’s also worth noting that other security companies, including Fidelis and FireEye have supported CrowdStrike’s analysis.