TORONTO - BlackBerry Ltd. says it has uncovered how China-backed hackers have been able to extract data from many of the world's servers for a decade without being noticed.

BlackBerry executive Eric Cornelius says the hackers have been skilful in disguising some of their software tools to appear like advertising software that poses a low-level security risk.

Cornelius says the tactics give the hackers the ability to extract information from huge amounts of valuable data on web servers using the Linux operating system.

He says the hacker tools aren't new but were mostly overlooked because most cybersecurity efforts are focused on mass market operating systems such as Microsoft Windows and Google Android.

BlackBerry says in a 44-page report that five separate groups with links to the Chinese government have been targeting Linux systems for a decade.

The federal government's Canadian Centre for Cyber Security says it works with partners to monitor and deal with potential threats but it doesn't comment on specific incidents.