Part of the CustodyStress archive of observed Bitcoin custody incidents
CS-00569
Documentation absent — Zaif (2018)
IndeterminateCase description
Zaif's September 2018 hack involved funds stored in hot wallets, 32% of which were Zaif's own reserves and 68% customer assets. The exchange had never disclosed to customers what proportion of their assets were held in hot versus cold storage. The two-hour window between theft and detection was attributed to inadequate real-time monitoring.
Custody context
| Stress condition | Documentation absent |
| Custody system | Exchange custody |
| Outcome | Indeterminate |
| Documentation | Unknown |
| Year observed | 2018 |
| Country | Japan |
Structural dependencies observed
What this illustrates
Nobody had written down how to get back in. That knowledge existed only in the owner's head. It's not clear whether anyone ever regained access.
Outcome interpretation
Not enough information is available to determine the outcome.
Source
Publicly Reported
Evidence type
News article
Related cases involving documentation absent
This archive documents observed custody survivability failures. It does not attempt to document all Bitcoin losses or security incidents.
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Framework references
Where Bitcoin Custody Intersects Legal and Fiduciary Authority
Where custody creates gaps in estate planning, fiduciary duty, and professional responsibility.
Professional Scope Boundary Matrix
What each professional or product covers, what they do not, and where gaps form between them.
The Independent Assessment Layer in Bitcoin Custody
How independent diagnostic layers emerge when multiple parties depend on shared infrastructure.