ESF: Controls: Update and PatchBy Mike Rothman
Running old software is bad. Bad like putting a new iPad in a blender. Bad because all software is vulnerable software, and with old software even unsophisticated bad guys have weaponized exploits to compromise the software. So the first of the Endpoint Security Fundamentals technical controls is to make sure you run updated software.
Does that mean you need to run the latest version of all your software packages? Can you hear the rejoicing across the four corners of the software ecosystem? Actually, it depends. What you do need to do is make sure your endpoint devices are patched within a reasonable timeframe. Like one minute before the weaponized exploit hits the grey market (or shows up in Metasploit).
Assess your (software) assets
Hopefully you have some kind of asset management thing, which can tell you what applications run in your environment. If not, your work gets a bit harder because the first step requires you to inventory software. No, it’s not about license enforcement, it’s about risk assessment. You need to figure out the your software vendors’ track records on producing secure code, and then on patching exploits as they are discovered. You can use sites like US-CERT and Secunia, among others, to figure this out. Your anti-malware vendor also has a research site where you can look at recent attacks by application.
You probably hate the word prioritize already, but that’s what we need to do (again). Based on the initial analysis, stack rank all your applications and categorize into a few buckets.
- High Risk: These applications are in use by 50M+ users, thus making them high-value targets for the bad guys. Frequent patches are issued. Think Microsoft stuff – all of it, Adobe Acrobat, Firefox, etc.
- Medium Risk: Anything else that has a periodic patch cycle and is not high-risk. This should be a big bucket.
- Low Risk: Those apps which aren’t used by many (security by obscurity) and tend to be pretty mature, meaning they aren’t updated frequently.
Before we move on to the updating/patching process, while you assess the software running in your environment, it makes sense to ask whether you really need all that stuff. Even low-risk applications provide attack surface for the bad guys, so eliminating software you just don’t need is a good thing for everyone. Yes, it’s hard to do, but that doesn’t mean we shouldn’t try.
Defining the Update/Patch Process
Next you need to define what your update and patching process is going to be – and yes, you’ll have three different policies for high, medium and low risk applications. The good news is your friends at Securosis have already documented every step of this process, in gory detail, through our Patch Management Quant research.
At a very high level, the cycle is: Monitor for Release/Advisory, Evaluate, Acquire, Prioritize and Schedule, Test and Approve, Create and Test Deployment Package, Deploy, Confirm Deployment, Clean up, and Document/Update Configuration Standards. Within each phase of the cycle, there are multiple steps.
Not every step defined in PM Quant will make sense for your organization, so you can pick and choose what’s required. The requirement is to having a defined, documented, and operational process; and to have answered the following questions for each of your categories:
- Do you update to the latest version of the application? Within how soon after its release?
- When a patch is released, how soon should it be applied? What level of testing is required before deployment?
In a perfect world, everything should be patched immediately and all software should be kept at the latest version. Unless you are talking about Microsoft Vista <grin>. But we all know the world isn’t perfect and there are real economic and resource dependencies to tightening the patch window and buying software updates – and discovering more bugs in the patches themselves. So all these factors need to be weighed when defining the process and policies. There is no right or wrong answer – it’s a matter of balancing economic reality against risk tolerance.
Also keep in mind that patching remote and mobile users is a different animal, and you have to factor that into the process. Many of these folks infrequently connect and may not have access to high-bandwidth connections. Specifying a one-day patch window for installing a 400mb patch at a mobile office in the jungle may not be practical.
Tools and Automation
Lots of tools can help you automate your software updating and patching process. They range from full-fledged asset and configuration management offerings to fairly simple patching products. It’s beyond the scope of this series to really dig into the nuances of configuration/patch management, but we’ll just say here that any organization with more than a couple hundred users needs a tool. This is a topic we’ll cover in detail later this year.
The next endpoint control we’ll discuss is Secure Configurations, so stay tuned.