SAN FRANCISCO — Online advertising offers marketers the chance to aim ads at very specific groups of people — say, golf players in Illinois who make more than $150,000 a year and vacation in Hawaii.
But two recent academic papers show some potential pitfalls of such precise tailoring.
Both papers focus on Facebook ads and show that in certain circumstances, advertisers — or snoops posing as advertisers — may be able to learn sensitive profile information, like a person’s sexual orientation or religion, even if the person is sharing that information only with a small circle of friends. Facebook does not share such information with advertisers.
The papers come amid an intense focus on vulnerabilities in Facebook’s privacy safeguards.
In one paper, researchers from Microsoft in India and the Max Planck Institute for Software Systems in Germany found that it was possible for an advertiser to find the stated sexual preference of Facebook users.
The researchers created six nearly identical Facebook accounts, three for men and three for women. The one significant difference was that in one account for each gender, the profile specified that the user was “interested in” people of the same sex.
Not surprisingly, the different accounts were shown different ads, because advertisers can specify what types of people they want to reach on the site. In particular, the accounts that appeared to belong to gay people received ads for things like gay bars.