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A Closed Off System?
AnarkiNet wonders: "In an age of malware which installs itself via browsers, rootkits installing themselves from audio cds, and loads of other shady things happening on your computer, would a 'Closed OS' be successful? The idea is an operating system (open or closed source), which allows no third party software to be installed, ever. Yes, not even your own coded programs would run unless they existed in the OS-maker-managed database of programs that could be installed. Some people might be aghast at this idea but I feel that it could be highly useful for example in the corporate setting where there would be no need for a secretary to have anything on his/her computer other than the programs available from the OS-maker. For now, let's not worry if people can 'get around' the system. If each program that made up the collection of allowed programs was 'up to scratch' and had 'everything you need', would you really have an issue with being unable to install a different program that did the same thing?"
Doesn't a live OS CD such as Knoppix achieve this goal? These are usually built for "everything you need" for a particular purpose. You can still access and create data on disks on that system, but you never corrupt the programs themselves. If all the applications being used are web based, then things are even simpler - simply boot up with Knoppix, open Firefox and you are ready to go.
Amanda: Open Source Backup Software
Windows has long been able to do this via Group Policy. You can specify that only programs signed with specified Authenticode keys can be run, effectively locking the system. Since all OS files are signed by Microsoft and anything a corporation would need could be signed, then if a corporation wanted a locked-down box, then they'd just specify the allowed keys and block everything else.
It'd be a huge nuisance but it's possible today.
No. LiveCDs do offer read-only system images. But they do nothing whatsoever to prevent other programs from being run. I.e. programs downloaded from the net, autorun(or manually) from cd. LiveCDs get you the benefit that each reboot resets you to an known state. That is quite different from an OS which only allows programs from a blessed whitelist to execute. One scenario might be the discovery of way to remotely log into the system. In the livecd case, the attacker can now run whatever program they want, and likely regain entry in an identical fashion should the system be rebooted. What the author of this post is interested in, is a system what would not let the attacker with remote login be able to execute any code not on the blessed whitelist. Now mind you, the idea that such a system would be 'invulnerable' is ludicrous. The XBox seems the quintessential example of a system which tried to achieve this design goal. My XBox currently runs ssh, freevo, and any executable I want, proving it is difficult to achieve a successful implementation of such a design. -jdog
SELinux policies. You can configure SELinux to have a default deny to execute files that aren't on an approved list of executables, and also ensure that only trusted persons have access to change those files.
Marxism is the opiate of dumbasses