The dangers of social media have been pointed out in a federal government review of social media and defence, which was finalised in March but has not been acted upon, Defence sources said.
The review found an "overt reliance" on privacy settings had led to "a false sense of security" among personnel.
The review warns troops to beware of "fake profiles, media personnel and enemies create fake profiles to gather information. For example, the Taliban have used pictures of attractive women as the front of their Facebook profiles and have befriended soldiers."
Australian soldiers are now being given pre-deployment briefings about enemies creating fake profiles to spy on troops.
Personnel are also being warned that geo-tagging, a function of many websites that secretly logs the location from where a post is made or a photo is uploaded, is a significant danger.
Family and friends of soldiers are inadvertently jeopardising missions by sharing confidential information online, Australia's Daily Telegraph reported.
Three Australian soldiers were this month murdered inside their base, allegedly by an Afghan Army trainee.
Many of the 1577 Defence members surveyed for the review had no awareness of the risk, it said, adding 58 per cent of Defence staff had no social media training.
Surveyed troops said social media open "a whole can of worms when it comes to operational, personnel and physical security".
"Many individuals who use social media are extremely trusting," the review said. "Most did not recognise that people using fake profiles, perhaps masquerading as school friends, could capture information and movements.
Few consider the possibilities of data mining and how patterns of behaviour can be identified over time," the review added. The review recommended education for family and friends on the dangers of sharing details like names, ranks and locations.
Several troop members have argued for a total social media ban. "I see too many members who post info/pics of themselves which identify ... what unit they belong to and where they are serving," a soldier said.
Security expert Peter Hannay, from Edith Cowan University's school of computer and security science, said geo-tag information "can be data-mined and sold to anybody".