Breachesby GlyphMicrosoft
Disclosed Mar 2, 2021Confirmed
Hafnium exploits Exchange Server zero-days to breach on-premises mail servers
Microsoft disclosed that a China-based state-sponsored actor it calls Hafnium used previously unknown exploits in on-premises Exchange Server to access email accounts and install web shells, and released emergency patches; many organizations worldwide were compromised.
What is known
| People affected | Not stated in the sources we have |
|---|---|
| Disclosed | Mar 2, 2021 |
| Attack | Hacking |
| Data exposed | EmailsCredentials and tokensMessages |
| Sector | Tech · US |
| Status | Confirmed |
Sources
Notices filed
Other breaches at Microsoft
Hijacked Microsoft GitHub repos pushed password stealers to AI coding tool usersSupply chain exposed credentials and tokens and passwords.Supply chainTechUSUnverifiedJun 8Microsoft 365 Copilot Chat bug processed confidential-labeled emails for weeksAI or model exposed messages.AI or modelTechUSUnverifiedFeb 18Storm-2139 used stolen customer credentials to hijack Azure OpenAI accountsCredential stuffing exposed source code, API keys, credentials and tokens and internal documents.Credential stuffingTechUSFeb 26, 2025Russian state hackers access Microsoft senior leadership email accountsHacking exposed emails, messages, internal documents and source code. Reported to the SEC 8-K.HackingTechUSJan 19, 2024AI research team's overly permissive SAS token exposed 38TB of internal dataExposed data exposed credentials and tokens, internal documents, messages and passwords.Exposed dataTechUSUnverifiedSep 18, 2023China-based Storm-0558 forges tokens with stolen Microsoft key to read government emailHacking exposed emails and messages.HackingTechUSJul 11, 2023Misconfigured Microsoft storage exposes prospective customer business dataExposed data exposed names, emails, phone numbers and internal documents.Exposed dataTechUSUnverifiedOct 19, 2022Lapsus$ compromises a Microsoft account and leaks Bing and Cortana source codeHacking exposed source code.HackingTechUSMar 22, 2022SolarWinds attackers view Microsoft source code repositoriesSupply chain exposed source code.Supply chainTechUSDec 31, 2020
History of this record
First recordedby seedSource
First seen 2026-09-25 (Research), confirmed by Research. Record counts are as reported. Not legal advice.