Software Trustworthiness

We rely on many systems to function and to do so safely and securely often without too much thought, whether it is utilities such as the electric grid, transportation such as airlines, automotive or rail travel, medical care or the delivery of goods. We normally expect and trust systems to “simply work”. Occasionally we are unpleasantly surprised such as with the fires in California and elsewhere leading to loss of electrical service after the event, planes crashing due to design issues, autonomous cars not negotiating lanes safety, or supply chains being disrupted.

We place enormous trust in the systems we rely upon. As these systems depend more and more on software to function it becomes essential to understand software and in particular how to have software that can be relied upon for a trustworthy system.

Trusting software requires confidence in the organization that produced it (“Do they do things in a way that inspires confidence? Does the leadership care about quality, safety, and so on or just profits? ” etc.), confidence in the actual products (“Was the airplane assembled properly or were incorrect bolts used?”), and confidence in the service associated with the system (“Is maintenance performed regularly and properly?”).

The reality is that we care about the “complete product”, everything about it. This is especially important to understand with software. Trust depends on evidence that the complete product is trustworthy. As defined in the IIC, trustworthiness is about a number of interacting characteristics, specifically safety, security, reliability, resilience and privacy. We have written about trustworthiness in the Industrial Internet of Things Security Framework, an IIC safety challenges white paper and an entire IIC Journal of Innovation issue devoted to Trustworthiness.

We have just published a new article on Software Trustworthiness Best Practices. In this paper we outline the entire lifecycle, including the importance of communicating and validating requirements, proper architecture and design, providing enough support for implementation and testing (including tools), validating, operating and decommissioning software. We also raise the value of software protection which is not always considered. The following diagram from the paper shows the lifecycle:

The paper includes practical discussions of issues such as software updates, end-of-life strategy and software protection – all topics that can be ignored when focused on software implementation. The appendix includes a software lifecycle checklist that should be helpful as well as some examples of failures related to software.

Software trustworthiness is essential to creating trustworthy systems and considerations of the topics and practices in the paper should help with the journey toward more trustworthy systems.

IIC IoT Security Maturity Model (SMM)

The Industrial Internet Consortium (IIC) has just published the IoT Security Maturity Model Practitioner’s Guide or SMM (IIC press release). Also published is an update to the earlier IoT Security Maturity Model: Description and Intended Use white paper.

This IoT Security Maturity Model is timely, needed and new since it incorporates business, process, technology and operations aspects, and considers the security need from an integrated perspective including various contexts (end-end, device, edge, cloud, etc) and viewpoints such as information technology (IT) as well as Operational Technology (OT).

The IoT Security Maturity Model is a strategic document addressing the challenge of how to invest appropriately to address security needs and as a strategy provides an approach and model as well as actionable guidance. The need is to invest appropriately to address concerns, without investing too much or too little and by focusing in the areas that matter. The strategy is holistic, considering business, process, technology and operations.

An important concept is that of maturity. This is not the same as security levels, since it is about the degree of fit of the solution to the need. Thus if a situation does not require much security then even if few security mechanisms are applied the solution can be mature, since it is possible to demonstrate confidence that the correct approach has been taken.

The general approach is for business owners and technology owners to work together to set targets, then perform an assessment to determine the current state, identify and mitigate gaps, and then repeat this process periodically as threats, technologies and business concerns change. This creates a continuous improvement cycle.

The model has domains of governance (roughly process), enablement (technology) and hardening (operations) as well as the corresponding sub-domains and practices as shown in the following figure from the SMM:

Each domain, sub-domain and practice can have a comprehensiveness level associated with it, indicating the depth and completeness of that item, ranging from none, to minimal (1), ad hoc (2), consistent (3) and formalized (4). In addition, the model is extensible to address the needs of specific verticals (e.g. manufacturing, retail, medical etc) through the use of scope, to enable specifics relative to certain comprehensiveness levels to be defined. Scope also allows system specifics as well. A set of comprehensiveness levels including scope may be defined as an industry profile.

The IoT Security Maturity Model has a table for each of the eighteen practices, providing detail for each of the comprehensiveness levels, including an objective that can be used by business stakeholders, as well as a general description of the level, what needs to be done to achieve it, and indicators of accomplishment. Such indicators can be used to determine in an assessment if the level has been achieved.

The IoT Security Maturity Model includes examples drawn from different verticals for each of the practice comprehensiveness tables as well as case studies at the end. The case studies are based on real assessments that were done previously, recast into the IoT Security Maturity Model to demonstrate that it works for real cases as well as to provide examples that can be understood.

Best Practices from the IIC and elsewhere can be used to provide detailed guidance on addressing the gaps. We are also working on additional guidance in the form of mappings from IoT Security Maturity Model comprehensiveness levels to details in other frameworks like the IIC Security Framework, and IEC 62443, the NIST Cybersecurity Framework and others (e.g. comprehensiveness level 3 maps to this specific guidance). We also are looking to work with partners on creating profiles for verticals.

Thinking long term we have looked at how this model might also be applicable to the concept of Trustworthiness, which includes security, safety, reliability, resilience and privacy taken together and outlined some thoughts on this in the IIC Journal of Innovation Trustworthiness issue.

This post just introduces the IoT Security Maturity Model. For more complete details, definitions and explanations please refer to the Practitioner’s guide itself. If you would like to participate in further developing this work please join us at the IIC.

Insecurity in Depth

If I put a fence with a hole in it in front of a broken wall in front of a partly filled in moat, is my castle secure?

The answer is ‘No’.

On the other hand if the defects are not immediately visible and not lined up with each other, then having these three layers could stop some attackers completely, while others may need time to find the flaw in each. Thus it could require more time and effort on the part of an attacker.

If everyone in the village knows about the flaws, then there might as well not be any barriers. If every weekend they walk through the various openings to have a picnic on the castle grounds, then all know that these barriers are not meaningful, at least to those who are informed.

It is interesting that Defense in Depth was supposedly conceived by the NSA, or at least documented by them, the masters of penetrating systems. To be honest, security in depth has its place, since one of the rationales is that attackers may come from different points in the system, so different security measures may be needed to address different aspects of the overall concern. As the NSA notes, an understanding of the system, adversaries, risks etc is required. Thus “security in depth” has a place as part of a broader understanding but is not functional merely as a mantra.

Security in Depth is mentioned repeatedly in the OPM oversight hearing, an interesting view for both the questions and the answers or lack of answers. Mention of security in depth is usually followed by a statement that there is no security silver bullet (other than security in depth).

There is an alternative to security by depth which is security through simplicity.

Take the case of the OPM, where it is speculated that security clearance background check forms (form SF-86) were taken, each having a wealth of personal information about an individual and their contacts. Security technologies failed to prevent the breach or even detect it while it was in progress (while the OPM is not disclosing details, apparently there were first breaches of the contractors working for OPM, then at least two subsequent breaches. Information on one later breach was loaded into Einstein, an intrusion detection and analysis system , which then flagged a previously unknown earlier breach).

Rather than piling up all these questionable and complex technologies wouldn’t it have been simpler and safer to document and follow a single governance rule:

“All clearance forms and their related documentation, including backups, will be
immediately and completely destroyed following the decision whether to grant clearance on the basis of those forms.”

The principle here is that the information is collected to make a decision, so once the decision is made, get rid of the information. The only reason to keep the information is in the event that a mistaken decision was made, to go back and look for indications that could have indicated the mistake. Is the ability to go back worth the time, costs and risks of keeping the information? It seems not.

During the OPM hearings the question of priorities came up, with the theme of “Isn’t security your #1 priority, so why did you let this happen?”. There was no clear statement of the obvious, which might have been ‘No, security was not the only priority. The priority was the running of operational support systems for other functions, with security as an aspect of that.’

So if those in charge are not willing to destroy the records once a decision is made, what would be the next best alternative? Probably to keep those records on a machine without internet/network access in a locked room. This would raise the cost of adding or reviewing records. By why should they be online once a decision is made?

All of this leads to the question of whether the costs and risks of (in)security in depth are the primary concerns in this case when a policy decision to ‘Eliminate records that have served their purpose’ might have sufficed.

Technology mechanisms and the speed of deployment might not have been the core problem, but rather governance decisions.

Taking Time

Many things in nature take time.

There is a certain time frame (typically 9 months) to have a baby. You cannot accelerate the process. If honey hardens you can soften it in warm water but it takes time, boiling water won’t make it faster – it will just ruin the honey. You do not accelerate the process so that you have teenagers the week after they are born, it takes time to get there.

Why in business do we limit ourselves to very short time horizons, when some things take time?

The answer is presumably that we do not know the outcome, so want to manage the risk and limit the cost. With a pregnancy you pretty much can expect it will take 9 months, there is past experience.

That said, there are companies that are doing extremely well since they do take a long view, ignoring the chatter around them. We know who they are.