Hackers using the pseudonym “Guccifer 2.0” stole 19,252 Democratic National Committee emails and 8,034 attachments dated from January 2015 through May 2016. DCLeaks and WikiLeaks published the material in June, July, and November 2016, including donor information, personal phone numbers, and data that could facilitate identity theft. The disclosures showed DNC officials discussing ways to damage Bernie Sanders’s campaign despite the committee’s public neutrality. A May 2016 exchange proposed having the media question Sanders about whether he was an atheist, while other messages showed officials deriding his campaign and discussing pressure on journalists. The controversy led Chair Debbie Wasserman Schultz to resign on July 24, 2016, followed by the departures of CEO Amy Dacey, CFO Brad Marshall, and Communications Director Luis Miranda; the DNC later apologized to Sanders and his supporters.
The attack also became a major cybersecurity and election-integrity scandal. On October 7, 2016, the Department of Homeland Security and the Office of the Director of National Intelligence said with confidence that the Russian government directed the breaches and release of the material to interfere with the election. On July 13, 2018, Special Counsel Robert Mueller indicted 12 Russian military-intelligence officers, alleging that they operated the Guccifer 2.0 persona and coordinated with WikiLeaks; WikiLeaks founder Julian Assange denied that the source was Russia, and Russian officials denied involvement. FBI Director James Comey testified that investigators received server copies and CrowdStrike forensic evidence but not direct physical access to the DNC servers. The episode left lasting consequences for political-party cybersecurity, election defenses, and public trust in digital information operations.