How does Facebook disable the browser's integrated Developer Tools?

Question

So apparently because of the recent scams, the developer tools is exploited by people to post spam and even used to \"hack\" accounts. Facebook has blocked the developer too

Answer 1

I'm a security engineer at Facebook and this is my fault. We're testing this for some users to see if it can slow down some attacks where users are tricked into pasting (malicious) JavaScript code into the browser console.

Just to be clear: trying to block hackers client-side is a bad idea in general; this is to protect against a specific social engineering attack.

If you ended up in the test group and are annoyed by this, sorry. I tried to make the old opt-out page (now help page) as simple as possible while still being scary enough to stop at least some of the victims.

The actual code is pretty similar to @joeldixon66's link; ours is a little more complicated for no good reason.

Chrome wraps all console code in

with ((console && console._commandLineAPI) || {}) {
  
}

... so the site redefines console._commandLineAPI to throw:

Object.defineProperty(console, '_commandLineAPI',
   { get : function() { throw 'Nooo!' } })

This is not quite enough (try it!), but that's the main trick.

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Epilogue: The Chrome team decided that defeating the console from user-side JS was a bug and fixed the issue, rendering this technique invalid. Afterwards, additional protection was added to protect users from self-xss.