Of all the databases a wealth haven would least like to lose, this one is near the top. A cyberattack has reached the data of about 31,000 people in Liechtenstein’s register of the individuals behind its companies, foundations and trusts. The government disclosed the breach on Monday.

Intruders reached the “register of economic beneficiaries” overnight from Wednesday into Thursday last week, the Associated Press reported. Officials noticed on Thursday, moved to secure the data and took the system offline. So far, they say, no one altered or deleted anything.

Why this list matters

This is not a routine customer database.

A beneficial-ownership register names the people who ultimately control a company or foundation, the humans behind the paperwork. Countries keep these lists precisely to fight money laundering and terror financing. A break-in hands whoever did it a map of who really sits behind the structures.