HAFNIUM
China-linked cyber espionage actor (HAFNIUM / Bohrium) responsible for the March 2021 Microsoft Exchange Server zero-day campaign (ProxyLogon).
HAFNIUM is a China-linked actor that exploited four Microsoft Exchange Server zero-days in March 2021 (ProxyLogon) to plant webshells on tens of thousands of on-premises mail servers.
Definition
State-sponsored espionage group that gained world attention via the ProxyLogon Exchange campaign; focuses on mailbox access and long-term persistence via webshells rather than destructive malware.
Why It Matters / Profile
- Sponsorship: People's Republic of China (assessed)
- Active since: 2008
- Aliases: Bohrium, China-Stalker-8 (assessed)
Current Status
- Review status: published
- Last updated: 2026-08-26
- Evidence: 2 source(s) · 4 technique(s)
- Confidence: 86%
ATT&CK Techniques
Targets
- Government
- Education
- Telecom
- On-premises mail infrastructure
Timeline
- 2008-01-01 — Attributed origins (approx.)
- 2021-02-01 — Exchange zero-day campaign begins
- 2021-03-02 — Public disclosure; mass patching
Sources
Start Investigation
Move from reading to investigating HAFNIUM. The workspace is a structured analysis surface — not a chat — organised as:
- Question — what do you need to know about HAFNIUM?
- Evidence — assertions mapped to verifiable references.
- Timeline — events in chronological order.
- Related Entities — CVE, threat actor, campaign, malware links.
- Sources — NVD, CISA KEV, MITRE ATT&CK, vendor advisories.
- Notes — your own observations and working hypotheses.
AI assistance is limited to summarising, explaining, and suggesting related evidence. AI never completes your investigation, modifies entity relationships, or generates facts — all published analysis stays human-reviewed.
Recommended Tools
- IOC LookupSearch OpenTrojan intelligence for indicators attributed to this actor.Look up IOC
Every tool runs passively or locally — inputs are never stored and no target is scanned. Start an investigation on this entity →