The international survey with more than 400,000 respondents found 24% were unsure whether the information they are working with is confidential or not. That means they don't know whether or not they can safely share it with people outside the organisation risks leaking out, without the employees being aware of the hazard.

This "indicates poor training and follow-up by management," according to KnowBe4 research director Kai Roer.

"Managers have a responsibility to train their staff to treat the information they are working with in a good way. That as many as a quarter of employees are unsure about this indicates a considerable failing in many companies."

The company has an axe to grind, as it is a security awareness training provider. Its service includes training based on its chief hacking officer Kevin Mitnick's social engineering tactics.

The survey found considerable differences between different business sectors.

Up to 34% of respondents in the In the construction, education, transport and retail sectors said they were unsure about the confidentiality of the information they work with, but the figure was just 16% in banking and finance.

Roer points out that employment contracts often include non-disclosure agreements, so "these figures indicate that the issue has generally not been properly explained to or followed up with employees.

"When someone starts a new job, they are given access to a lot of information. It is the manager's responsibility to follow up and ensure that their employees are confident in their role and know how to handle the information they encounter.

"It is equally important to ensure that employees handle confidential information correctly as time goes on. It is not enough just to provide training when people join the organisation."