Posted 9 years 9 months 1 week ago.



This article generated signficant buzz. Although this website was down most of the time during that, due to the traffic. Discussion on HN @

Covered on : Forbes, The Verge, Business Insider, Pro Privacy, and many others.


Was trying out the Slack Mac client after we adopted Slack recently for our team communication.


The mac client asks you for an email address. Then it prompts you as to which group/team you wish to sign in. And then asks you for the password.


My first thought was “WTF!”


For those who don’t know, Slack is an online collaboration tool that allows teams to have chat rooms, file sharing etc with a powerful API that allows custom integrations as well.


As I suspected, I tried a random email address and it listed all the teams/groups that the person belonged to.


Like, when I gave in the email address of Microsoft CEO,..



It listed all the teams/groups he is part of!



The list is too huge for a screenshot and some of them are names of Microsoft Products that are apparently not announced/released yet!


Seriously? Now all you have to do to know what your competitor (using slack) is doing - is just download the Mac client and key in the email address of an employee from that company!


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Submitted by tanay on Wed, 10/08/2014 - 03:08