Facebook removes option to look up contacts by phone number from Messenger

Renowned reverse engineer Jane Manchun Wong says Facebook is removing the option to track contacts via phone number from Messenger, possibly because the option allows brute forcing to link accounts and random numbers.

Recently, another security researcher came out with the news that he linked 17 million random phone numbers to real people via Twitter by entering them into the Twitter app. Among those 17 million people were also prominent politicians. It’s possible that Facebook wants to avoid being in the news for the same reasons.

In the case of Twitter, a randomized set of two billion generated phone numbers were supplied to the Android app, leading to the 17 million hits. Twitter says it is working to fix this bug, but it remains to be seen how the platform will determine whether a given phone number is random or not. Facebook seems to be avoiding the whole issue by sacrificing the feature.

The ability to track users on a social medium by their phone number is intended to make the platform easier to use, and obviously only works if the targets have provided their number. Also, the person who performs the search usually has to provide his number himself.