Critical Security Controls: Getting to know the unknown

Published: 2015-12-21
Last Updated: 2015-12-21 00:54:45 UTC
by Daniel Wesemann (Version: 1)
1 comment(s)

The Critical Security Controls (CSC) were recently updated, and quite some changes were made. What did not change, though, was the order of sequence of the first four critical controls, which are:

CSC-1: Inventory of Devices
CSC-2: Inventory of Software
CSC-3: Known secure configurations
CSC-4: Continuous Vulnerability Assessment and Remediation

This order of sequence didn't happen by coincidence. If you don't know what is on your network, you stand no chance of keeping it configured securely, or keeping it up to date. Yet, time and again, in audits we encounter networks where >20% more IP addresses are in use in the server room than are actually accounted for in the inventory. Some of this discrepancy is explained by failover/redundancy addresses. But, on closer investigation, a good chunk of it is usually also chalked up to so-called "appliances" that are treated as black boxes, until an outage or hacker proves that they aren't. With the nascent increase of "internet of things" devices, this will only get worse. Recently, we discovered our first office building door control system with a full-fledged web page of its own, and video feeds covering everyone who walked in our out. No password needed, and running a JBoss version from the Flintstone age. The organization's IT department did not feel responsible for the box because it had been installed by the building management department. The latter in turn did not feel responsible for the box because their vendor had strategically opted to market the device as "maintenance free" and "easy to use".

Keeping these devices under control is indeed a challenge in the DHCP space of user workstations. But it shouldn't be all that hard in the data center! While naked servers might BOOTP to the install server, anything else speaking DHCP in a server room should be hunted down. If the static IP Address assignment inventory is up to date, then the summarized Netflow logs of the datacenter routers can be reconciled daily against the IP addresses that are known as being in use, and everything else will clearly stand out.

Keeping track of software (CSC-2) is a bit more challenging, since everything installed "above" the OS layer can come from a plethora of application vendors, and can (and do) bundle a plethora of libraries and tools. You might remember this mess from when you had to track down how many of your devices were affected by Shellshock, Heartbleed or the recent Java Object Deserialization vulnerability: It is hard to impossible to know with certainty which version is bundled into which product. Nonetheless, the Critical Security Controls have a fair point in stating that you can only secure and patch what you know is running in your environment, and no fight was ever won by giving up at the onset.

Once you have CSC-1 and CSC-2 reasonably backed into a corner and wrestled into submission, it is then time to start with CSC-3 and CSC-4. I'm not saying that any of this is easy, to the contrary, it is tedious and often thankless work. But the number of breaches that were directly or indirectly caused by the organization not knowing what they were running, and not keeping it shipshape, is legion. CSC-1/2/3/4 are indeed at the core of every system security program. If you feel wobbly about yours, start your 2016 with taking a serious stab at getting CSC-1 under control, and then proceed from there.

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Thanks for wording my @Work New Year's resolution for me! Now looking for takers in the organizations I work with. I'll apply the same documentation requirements for my @Home gear.

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