Two German researchers say they have exposed the porn-browsing habits of a judge, a cyber-crime investigation and the drug preferences of a politician.
The pair obtained huge amounts of information about the browsing habits of three million German citizens from companies that gather “clickstreams”.
These are detailed records of everywhere that people go online.
The researchers argue such data – which some firms scoop up and use to target ads – should be protected.
The pair found that 95% of the data they obtained came from 10 popular browser extensions.
The public information included links people shared via Twitter, YouTube videos they reported watching, news articles they passed on via social media or when they posted online photos of items they bought or places they visited.
In many cases, he said, it was even easier to de-anonymise because the clickstreams contained links to people’s personal social media admin pages which directly revealed their identity.