Security Through Obscurity…

Time and time again we are told the above doesnt work and yet it still happens, why and why is it important.

In the process of our big tracker project I’ve been looking at packages that do the job already and also a number of control systems. Bearing in mins what these do, there is no security on most of it and token security on one of them. You may think that this isnt a big thing and in most cases it isnt, but there are good reasons it is. So lets take a look at two culprits…

Veichle control Systems:
I’ve looked at three of these in the last few days and one thing is common with all three. No encryption, no ability to detect errors and no authentication. For the best part this isnt a huge problem, in fact its a boon, I know how all three work and can talk to them. However the bar is set low and any of them can be subverted easilly. In the case of the first two I looked out you wouldnt gain a lot past the ability to turn things on and off but the potential is there. The third is a fully integrated system and is designed to control all aspects of the vehicle including battery management and its also designed to be linked to an onboard computer, now here there is scope for trouble. The system concerned could easilly be subverted by malware and then the fun begins. Further digging on this one turns up no encryption is used on the comms link to the office either, but it gets worse…

Of the dispatch and tracking systems looked at not one uses encryption, for the more basic ones this means simply you can rap the tracking data out of the air and at least one was fooled easilly to connect to a wifi network and forwd the unencrypted traffic over my network, patient details, addresses etc all in the clear. This means that this data can also be modified so this particular system couldbe subverted pretty easilly with a laptop and either data creamed off and used for nefarious means (ask someone how expensive ambulance kit is!) or worse. Tracking data can be falsified, fed back to the base meaning the veichle doesnt show as being where it belongs and uh-oh, the SOS button isnt going to help if someone jumps the ‘bus’

There is no excuse for this. None at all and the scary thing is that the same can be found in Automotive systems from the factory and has recently been found in Avionics systems too!

Serial channels can simply and effectively be secured. Even our most basic bus system, TRNet uses authentication and device tracking mechanisms. If a device doesnt authenticate, its ignored, even if it does it must be recognised on the bus else the system, will lock the bus out. This is done by a few dozen lines of code and although it could be subverted with a moderate amoun of effort you’d need access to a lot of information to get started. This also allows us to give a mechanism for making sure the bus is reliable. Scarilly all but one of the three systems we looked at just kept sending the same data over and over again with no control path back to the master. Although it’ll work it means bit flips can happen in transmission and may be ignored (no CRC/Checksum used) and there is a wealth of data for someone to grab and decode.

Data channels running over a network should also be secured and only links trusted should be used. Again this is basic common sense and doesnt take a lot of code, for this application we are using a pretty hardcore authentication system based on AES but its neither difficult to do or expensive. With the system we have both ends of the chain must be compromised and in such a way that pe-encrypted data is grabbed, key shifts mean that just grabbing the encrypted stream and a session key wont help you, even if you do grab a key you need the previous key to use it so good luck.

There is still a strong sense in the embedded and bespoke software/hardware market that no one is interested in specialist applications, wont try and thus you dont need to bother about security above making it convoluted. This is fallacy, the value of the equipment on an ambulance is truly amazing to those not in the know so gaining the ability to send such a veichle to a false location of your choice, disabling its tracking  and ability to call for help is going to be of interest.


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