Wednesday, 13 April 2011

Evaluation Assurance Levels - EAL

EAL stands for evaluation assurance level and is a certificate of security for IT products measured against a set of common security criteria. The main source of information on EAL levels is the common criteria portal where you can find details of approved products and information on the criteria used for the EAL certifications.

Who uses it?

Your average network bod may not come across EAL very often. It tends to crop up in areas that are regulated by government bodies such as CESG who will often require EAL4 certified products for certain secure environments. However you don't just buy EAL4 kit and be government approved, it fits into a much larger security framework such as ISO27k dealing with everything from who gets into the building to how you manage changes to IT systems.

How does a product get EAL certified?

It is assessed against a set of common criteria by an approved agency. The developer of the system produces a security target (ST) document containing a list of features to be assessed.The ST is based on the criteria here. The process is long and expensive, according to wikipedia vendors were spending $1 - $2.5million to gain EAL4 certification in the 1990s.

What do you get when EAL certified?

Certified products are listed on the common criteria portal along with the rating granted, the ST it was assessed against and the assessment report. e.g. here (PDF) is the ST for the Cisco ASA as a firewall and here (PDF) is the assessment report. Interesting to note that the EAL4 VPN certificate was issued separately, so an ASA acting as both firewall and VPN endpoint is not a valid EAL4 solution, strictly speaking you would need two in series performing each task.

So what does it mean in to a network engineer?

Probably not a lot, it's a policy requirement for many places but the assessment is only against the device, not against the specific implementation of it. You could deploy an EAL4 firewall with a policy of "permit any any" and it's still an EAL4 device! At that point the other security mechanisms should have stopped you from putting it on the network.

If you are involved in hardware selection for a regulated organization then you may need to use EAL4 devices in certain situations.

What is required to meet the various levels?

The EAL process is broken down to cover the following aspects of a system:
Development, documentation, life-cycle support, security target evaluation, testing, vulnerability assessment.

Each EAL level goes into slightly more detail, for example the "development" area at EAL1 requires a basic functional specification to be provided by the developer. EAL2 requires that same functional specification but expanded to include details of security inforcement. It also requires a security architecture description and a basic design. The specifics of those items are detailed here.

How long does it take to get EAL4?

It seems to vary from a very long time to aeons, certainly it's measured in years rather than months. A look on the NIAP CCEVS evaluation and evaluated list for firewalls shows a few examples:
Checkpoint R65 HFA01 on IPSO recorded as submitted Oct 2005 although R65 was released in 2007 so the process was started early during development. It passed March 2009. So that's 4 years to get certified and the product went EOL in March 2011, 2 years later.
Cisco ASA 8.3 as a VPN submitted November 2009 still not passed, predicted June 2011.
Palo Alto submitted various devices in December 2009 and still running.

What exactly is certified?

The certification is issued against a specific software release and hardware platform.

A specific version of the software you say? As in....minor version??

That is how the cert is written. The Cisco ASA obtained EAL4 for firewall purposes on version 7.0(6) of it's OS which was released in August 2006. Cisco have been patching and updating that for 5 years! The ASA is now up to release 8.4, which has been submitted again to CCEVS (scheme run by NIST and NSA) for evaluation.

In reality there will be a security assessor on the ground who will review the solution and hopefully be sensible about using a modern patched version of the OS and judge it acceptable to meet an EAL4 requirement, even if it's not strictly what's on the EAL4 certificate.

I don't know anyone who would tell you with a straight face that using a 5 year old OS on a firewall is going to increase your security!

What about high end firewalls?

There is a bit of a gap, if you need an EAL4 firewall with 10gig throughput then you're out of luck as the only one that's passed assessment is Checkpoint Power-1 on the 5075/9075, however that went end of life last month (March 2011). The closest is the Cisco 5580 which has been submitted for EAL4, due November 2011 and is arguably similar enough to the 5540 to be acceptable, however it's recently announced as being binned in preference of the 5585 so after August 2011 you can't buy one any more!

The security market moves quickly compared to the EAL assessments and it proves tricky.

The top end Cisco firewall platform is the 5585, not even showing as submitted for EAL evaluation yet.
Checkpoint has R71 under assessment now, predicted result in November 2011.
Palo Alto has various items aiming for November 2011, but their flagship model the PA-5000 is not listed as under assessment, it only recently hit market in the UK so EAL certification may not have been discussed yet.
Juniper have EAL4 for their ScreenOS platform the SSG, which goes EOL in 2013. They have EAL3 for Junos 9.3 on the SRX platform, the current version is 10.4. There doesn't appear to be any indication that the SRX security platforms have been submitted for EAL4 certification, although it would be surprising if that were the case as governments would be ditching Juniper en-masse before 2013.

So until November 2011 there are no EAL4 10gig firewalls. You'll have to build a farm of 1gig ones instead!

What alternative schemes are there?

FIPS-140 from NIST.
CAPS, the CESG Approved Product Scheme.

Is it worth me buying EAL4 products?

If you have to ask then probably not. If your business is regulated and the agencies setting those policies define EAL4 as a requirement then you have no choice.

For companies with the option I would say it's a helpful indicator but I would certainly use other aspects above the EAL status when selecting a device:

  • Performance.

  • Price.

  • Published security tests and exploits.

  • Staff familiarity.

  • Internal testing.

An EAL4 certificate does indicate that the product was developed following good practices and has a well defined and documented architecture. These are clearly good things in terms of stability and security. However not having EAL4 doesn't necessarily mean the product hasn't followed a good development process and isn't secure, it just means the manufacturer hasn't paid for it to be assessed.