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When you use FB and upload your contacts to FB, you are allowing them to target people like me (conscientious FB objector) without our permission.

To test the shadow information finding, the researchers tried a real-world test. They uploaded a list of hundreds of landline numbers from Northeastern University. These are numbers that people who work for Northeastern are unlikely to have added to their accounts, though it’s very likely that the numbers would be in the address books of people who know them and who might have uploaded them to Facebook in order to “find friends.” The researchers found that many of these numbers could be targeted with ads, and when they ran an ad campaign, the ad turned up in the Facebook news feed of Mislove, whose landline had been included in the file; I confirmed this with my own test targeting his landline number.

“It’s likely that he was shown the ad because someone else uploaded his contact information via contact importer,” a Facebook spokesperson confirmed when I told the company about ... show more