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The story of how not to do authorization, especially in areas important for life and property, such as, for example, managing an alarm through the application from the phone.
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A small preface. 3r3334. 3r3118.  
It all started with the fact that I built a house, and a house without a security alarm can exist in our realities, of course, but nothing can be left there in the slightest degree (the sad cases of the neighbors confirm this). While the decoration was being made inside and outside, the keying and disarming of the key did not cause any inconvenience.
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The house has a garage, the gate opens with a remote control and, accordingly, a car is placed there. If the house is guarded, the opening from the remote control will trigger a “alarm” at the gate and after 2-3 minutes the arrival of serious guys. To avoid this, you must first remove the guard (open the vestibule, attach the key, close the vestibule, get into the car again) and then open the gate. And somehow this procedure is a bit annoying, especially in winter, and indeed all the "magic" is somehow lost.
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Of course, you can slyly do it so that opening the gate removes the alarm, but I haven’t gotten to that yet.
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But I heard that our security agency has a miracle application "Mobile Phoenix Keyboard". The application is not exactly theirs, but they work with it. With it, you can control the alarm from your phone, which more or less returns the joy of using all of this.
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3r3333. And now the story itself. 3r3334. 3r3118.  
To connect the security management from the application, you need to come to the office of the security agency, find the necessary engineer, pay 400 rubles for the “tune-up” to the cashier, and you will be given an account that is driven into the settings on the phone and voa-la, you can steer the guards as you like, receive push notifications and not know grief.
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Everything would be fine, but when you register, you are given a login in the form of three letters, for example abb (initials), and the password is made from the last four digits of the phone number (as the engineer said - not to be forgotten), that is, for example 0808. A little taken aback by what he heard, asked if it was possible to set another password, they said that it was possible, but only numbers. Well, ok, I asked myself the right password and retired to test how everything works.
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In my head, meanwhile, an idea had already matured - but would you try
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We take the iPhone, connect it to the Mac, run: rvictl -s iPhone_UDID , we cling to the new interface through Wireshark and see how it works and what it sends our application. You can take other devices /tools, but I have such.
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3r361.
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It works, it turns out, through the wamp protocol - this is essentially almost the same web socket. Naturally, nothing is encrypted and you can see exactly how requests are sent and actually repeat them.
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Now we try to reproduce the received requests. All this for the speed of tests, you can put an extension for chrome like "Web Socket Client" and try there.
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After making sure that everything works exactly as expected, we quickly write the client, for example, to node.
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We notice that the API responds to us with different messages when the user is not found at all and when the password is incorrect. This will speed up the process.
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Our client will be pretty dumb, but effective nonetheless. The client enumerates all logins consisting of 3 letters. If the login exists, it starts brute force password search; if not, proceed to the next one. The password is moved in the range from 0000 to 9999.
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We start all this and wait. The logins moved quickly enough (10 minutes), it turned out about 150 pieces (the service is not so much used). The password for each login is approximately 8 minutes. There are no restrictions on checking in the API. And you can hammer multithreaded.
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Passwords were selected in 100% of cases. If the password is successfully selected, the API spits out such information as: the owner’s full name, addresses (there may be a lot of objects), some tokens (apparently for sending them to push), session id, and so on.
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Having authorized, it is possible to disarm the whole object accordingly. Objects themselves came across rather distant from the city. If this information fell into the hands of the “bad guys,” the autopsy, as it were, of a protected object, would have passed without any problems, and then calmly could have been armed, and no one would have noticed anything.
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Realizing that I myself am a client of this office - it became a bit uncomfortable.
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One thing pleases, apparently some kind of monitoring the company has or may have accidentally noticed, but after a while the application stopped accepting passwords and suggested contacting the office.
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As a result, all logins changed and made normal passwords. The protocol, however, was as unencrypted, and remained, but at least something.
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What is this all about? Maybe after that someone will want to make their system a bit safer, and someone who uses the same service with similar passwords will look at it from the other side and ask for action. Such simple actions will slightly increase the level of security. 3r3118.  
I deliberately do not give names here and as much as possible depersonalized all the data, so that whoever recognizes himself would come to conclusions :)
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P.S. This article is for informational purposes only, the problems described here are no longer relevant at the time of publication - the company took action.