Three groups targeted seven prominent companies in Canada, France, India, South Korea and the United States, Microsoft said.

The tactic represents the kind of digital spying technique that would have given hackers access to machines belonging to job applicants positioned near military organizations — just the kind of targets that a foreign government would value.

This time, the spies were trying to get access to European defense firms, McAfee says.

In recent months government hackers from North Korea have been turning to deploying their own ransomware, according to Kaspersky research.

North Korean government-linked hackers have been aggressively deploying a multi-stage malware framework for two years in a ploy to expand their target sets, according to Kaspersky.

It's a cautionary tale in the use of social engineering for espionage.