In less than a month's time, the "Unistellar" hacking group has reportedly accessed over 12,000 unsecured MongoDB databases and stolen their contents, apparently holding them for ransom.

Security researcher Sanyam Jain initially discovered the wiped databases late last month using the BinaryEdge scanning service, according to a BleepingComputer report last Friday. The 12,564 sabotaged databases make up roughly 20 percent of the 63,000+ publicly configured MongoDB identified via BinaryEdge, the report continues.

The attackers' m.o. is to replace the original contents of accessed databases with a message instructing owners to contact a Unistellar email address if they wish to restore their data. Presumably, the attackers then demand a cryptocurrency-based payment from the victims.

Earlier this month, researcher Bob Diachenko reported one of these attacks after an open MongoDB database containing more than 275 million sensitive records on Indian citizens was targeted by the Unistellar hackers.