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Securing a Private Intranet?
crustythecrab asks: "My company wants to take a web-based data management system I wrote which runs on a closed network not connected to the internet and put it out on the net so everyone can access it remotely. The number one issue of course is security, and I've been asked to write a paper on how to make the system 'secure' in order to convince management that it will be safe to proceed. But the question runs through my mind: How secure is 'secure'? I'm running all UNIX, no Windows of anything on the server side, and I'll certainly recommend a VPN, but since nothing is 100% secure, I was wondering what the current state of the art in 'Intranet' security is. Are there any novel new concepts out there. Or do you just put up a VPN and hope for the best?"
Your Security will only be as strong as the most easily tortured employee. Plan wisely.
Prefix everything I have to say with "Nothing is perfectly secure", and keep in mind that poking holes in security concepts is often a lot easier than implementing something effective, efficient, and that makes sense from a business perspective.
Some potential options are:
* Authentication / Confidentiality - Application layer
- Consider using an authentication scheme for access to portions of your web site - this can be through self-generated X.509 certificates, distributed to your users for example. Such certificates have the advantage of providing both authentication, and encryption at the application layer.
* Authentication / Confidentiality - network layer
- A VPN is a step in the right direction I suspect. Something like the openvpn suite may be appropriate. If you wish to use openvpn for authentication as well, you'll probably need to find a relatively secure mechanism to distribute key data.
You may wish to consider making up a 'autorun' CD for each user, which contains the key data, establishes the vpn link, copies the x.509 key to the appropriate location in the users browser config files, and connects to your application. If your end-users are windows machines, it should be relatively easy to automate. If you have unix boxes at the user level, then you may be able to get away with something a little less streamlined.
In this setup, your 'CD' becomes your key. When your user wants to access the 'work application', they pop the CD in their drive, and wait for a connect. You may wish to overlay password access controls on either your openvpn or http server, in order to guard against loss of a CD implying access to your network. In addition, auditing access to your network is a critical (if somewhat difficult) part of your security profile.
Alternatively, you could investigate:
* hardware tokens, or SecureID related technology. Many of these systems use usb these days, so there's less of a problem with lack of card readers like there used to be.. It really depends on how much you really want to spend.
* Dial up. This is becoming more and more difficult though - often, a user will have a modem and ADSL/Cable link active at the same time, so without additional security controls, you effectively have an uncontrolled gateway to your network.
However, in summary, I'd recommend:
* Application level identification (and possibly encryption). Potentially x.509 certificates, or strong passwords.
* Network level identification and encryption (potentially something like openvpn, but not using the zero-configuration options)
* Some form of effective auditing in lieu of an effective certificate revocation service.
Again... security is very much a marriage of risk, threat, and cost. Some of the above solutions are probabably worth considering in low threat environments, where cost is an issue, and the number of users is easilly manageable. When you have a high threat environment, or where money is not an issue, then a more 'packaged' solution would probably be appropriate.
Red.