Two Factor Authentication Systems?

HerculesMO asks: "I've been given a project to undertake that involves setting our internal network systems up to have two factor authentication. I need suggestions to take in front of our CIO that shows how the security model works, cost vs benefit/features, and the different options. At this point, the name brand is RSA and I'm pressed to find any others even though I've done looking around. We are open to biometric tokens as well, because they may be used for digital certificate signing for e-mails. Sadly, it has to integrate with our Windows 2003 Active Directory set up... it's not Linux, but I figure Slashdot readers can come up with lots of Linux security tokens that will work under Windows too, so please have at it! :)"

Comments

RFQ

[chris_mahan]

RFQ to vendors. Let the CIO compare the proposal. Don't do his job. He's not cutting you a slice of his salary.

What you might ask /. is what to put in the RFQ together.

But you know your system and requirements best.

Couple of choices that I remember

[emag]

You've got a couple choices if you want a token-based dual factor authentication scheme. Of course, there's RSA's SecurID that you already know about. There's also CryptoCard, which IIRC can emulate some of the RSA tokens, and has its own scheme.

Now, what's nice about SecurID is AFAIR it's the only token that does *time*-based auth (ie, the displayed number sequences change constantly as a function of elapsed time). However, there's a really ugly problem with their auth servers that we accidentally discovered trying to set up a replicated server for failover purposes. To wit: the servers only sync based on a timed (as opposed to event-based) schedule. So, in the normal course of events, you can sometimes reuse the same token (# stream on the hardware device) even though they supposed to be single use. This happens when you attempt to have both servers service requests, and login 1 uses server A to authenticate against, and login 2 ends up using server B to authenticate in a very short period of elapsed time. Server A hasn't had a chance to tell server B yet that it's already seen that particular number sequence, so B happily accepts it.

Now, the devious-minded can see a problem here... You can be sniffing a network connection, get the token, pin, and password from the network ("hey, we have these hardware tokens, why should we ssh/ssl/vpn?" or what annoyed me, "we can't use ssh key authentication, we *must* use password auth with this"), then DoS one of the auth servers, and attempt a login with the same credentials, hoping to get an alternate, not-yet-synced auth server. Bang, you're in (eventually). So much for the whole non-replayable 2-factor authentication thing.

I don't think this problem was ever solved satisfactorially (I've since moved off that contract), but you can "solve" it by only having a single auth server...

Unfortunately, I know a lot less about CryptoCard, since we went with SecurID ourselves and didn't find the warts until later.

Oh, yeah, good thing this is just windowss, as linux was ok, but Digital Unix and Irix were a bitch to get working with SecurID.

Smart cards

[swillden]

There are several providers of smart cards for use as a second authentication factor. The one I'm most familiar with is ActivCard. Their stuff is reasonably good, and if it helps in your corporate environment IBM Global Services has a team that does a lot of ActivCard integration, so you can get plenty of support from a reliable provider (for a price :-) ).

IMO, smart cards are a better solution than SecurID tokens. They're cheaper, allow your logical authentication token to be the same card you use as an ID badge (and perhaps for door access) and can do a lot more things. They can act as one-time password generators, just like a SecurID (but guarantee non-reusability of the passwords, unlike SecurID, as mentioned by another poster) but they can also:

• Store public/private key pairs and certificates for strong web authentication, e-mail signing and decryption, PKI-based login, etc. Most cards can even generate the key pair on-board so that the private key *never* leaves the card, for when non-repudiation is valuable (signatures, mostly).
• Store username/password pairs for situations where one-time password or PKI authentication isn't workable. Done properly, it can be arranged so that cardholders never need to know the passwords, which are large, randomly-generated and changed automatically and frequently. That makes password-based systems nearly as secure as one-time password or PKI, but doesn't require fixing all of the apps.
• Store biometric templates to allow a third authentication factor to be deployed without a central database of biometric data. Note that, IMO, biometrics are highly overrated as a security device for logical access control. Still some people want them, and smart cards can help make them more manageable.
• Provide other services, like electronic cash for the cafeteria, etc.

The major disadvantage of smart cards as compared to SecurID tokens is that smart cards have no display, so you need a smart card reader to use them. This means that, for example, you could use a SecurID to authenticate to a corporate web site from an Internet cafe, whereas you might not be able to attach a smart card reader to some random PC. As a partial solution, handheld, calculator-like smart card readers exist that can retrieve a one-time password from the card and display it on a screen. I say it's a partial solution because carrying two devices is less convenient than one SecurID. The cost of such a device, plus a card, plus a regular PC-attachable card reader all totals to something less than a SecurID token.

Disclaimer: I work for IBM Global Services, in the group that does smart card stuff, including ActivCard integration work, so I have some biases, but I also have a deep knowledge of the industry and, at present, I think the ActivCard product set is the best choice available, overall. Cryptocard has some good stuff as well, but it's not as complete or as mature, especially in the area of enterprise card management (issuance, re-issuance, revocation, etc. all needs to be integrated and automated, complete with automatic key escrow and recovery, etc.). Both ActivCard and Cryptocard support Linux and OS X, though ActivCard's support for Tiger isn't there yet, and Cryptocard's is, mostly. ActivCard also supports Solaris, including SunRay environments. IBM has some nice assets that we use to build customized solutions, but our stuff is focused more on multi-factor biometric authentication for physical security than logical security.