Canadian researchers have uncovered a vast "Shadow Network" of online espionage based in China that used seemingly harmless means such as e-mail and Twitter to extract highly sensitive data from computers around the world.

Stolen documents recovered in a year-long investigation show the hackers have breached the servers of dozens of countries and organizations, taking everything from top-secret files on missile systems in India to confidential visa applications, including those of Canadians travelling abroad.

Read the entire Globe and Mail article here.