Researchers from the cybersecurity firm Digital Shadows said a scanning tool used in the first three months of 2018 found mountains of private data online from people and companies across the world.

The unprotected data amounted to some 12 petabytes, or four thousand times larger than the "Panama Papers" document trove which exposed potential corruption in dozens of countries.

"These are files that are freely available" to anyone with minimal technical knowledge, said Rick Holland, a vice president at Digital Shadows.

Holland told AFP his team scanned the web and found unsecured files, adding "we didn't authenticate to anything."

The availability of open data makes it easier for hackers, nation-states or rival companies to steal sensitive information, Holland said.

"It makes attackers' jobs much easier. It shortens the reconnaissance phase," he added.

The researchers said in the report that even amid growing concerns about hackers attacking sensitive data, "we aren't focusing on our external digital footprints and the data that is already publicly available via misconfigured cloud storage, file exchange protocols, and file sharing services."

A significant amount of the data left open was from payroll and tax return files, which accounted for 700,000 and 60,000 files respectively, Digital Shadows said.

It noted medical files and lists were also weakly protected, with some 2.2 million body scans open to inspection.

Many corporate secrets were also out in the open including designs, patent summaries and details of yet-to-be-released products.

"While organizations may consider insiders, network intrusions and phishing campaigns as sources of corporate espionage, these findings demonstrate that there is already a large amount of sensitive data publicly available," the report said.

The researchers said about 36 percent of the files were located in the European Union. The United States had the largest amount for a single country at 16 percent, but exposed files were also seen around the world including in Asia and the Middle East.

About seven percent of the data was in "misconfigured" cloud Amazon cloud computing storage. Holland said the main problem was not in the cloud computing itself but how users manage their data.

In some cases, users "are backing up their data to the (open) web without knowing it," Holland said.

The majority of the files found by Digital Shadows were exposed by poor security practices in servers and file-sharing protocols.

"Third parties and contractors were among the most common sources of sensitive data exposure," the report said.