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Solution Risk, Vulnerability, Threat and Mitigation - Does Risk Need to be Separate from Event?

Changes have been made to TRAK to support the description of risk and event sequences in the guise of the SVp-11 Solution Event Causes and SVp-13 Solution Risk Viewpoints. This has been a piece of work underway for at least 3 years but it seemed necessary to publish it so that the viewpoints and tuples can be exposed to wider testing i.e. used in anger.

As with most of this sort of work there is a limit to the amount of theorising that is possible and it’s necessary to test the pragmatism and utility. It’s likely therefore to undergo some tweaking. If any relationship or metamodel entity is not needed then it should be removed since the overall aim is to work with the minimum metamodel needed to just be adequate. A larger metamodel is not only harder to maintain and keep consistent but because it is only there to support the concerns in the set of TRAK viewpoints (specifications for views cf ISO/IEC/IEEE 42010:2011) it follows that a larger metamodel makes definition of a consistent set of viewpoints harder. With more entities and relationships it is also likely that an architecture description can become more complex and require more effort to present it clearly to get the meaning across (at least to a Mk 1 Human Being since being based on triples a TRAK architecture description is machine-readable and analysable). Every tuple in the TRAK metamodel has therefore to earn its keep / justify not being removed.

Solution Risk

In a previous posting I identified why we think, in TRAK at least, that a risk is a type of event and why many of the current definitions of risk do not actually define what a risk is (only how you might calculate a number or metric i.e. probability of occurrence x impact severity).

We’ve tied risk to the solution because we think that this is where it most often manifests itself in terms of design features or changes to the design of the system of interest to mitigate it. In engineering terms it is really the cumulative risk exposure to people that drives design change hence it makes sense to be able to relate risk, vulnerability, threats and mitigation to a solution design whether the causing agent or the impacted one.

TRAK therefore supports the following triples / tuples for describing risk:-

https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons” href=“https://commons.wikimedia.org/wiki/File%3ATRAK_metamodel_part_2_safety_security.jpg”>

• Resource (System, Software, Physical, Role, Job or Organisation) has Vulnerability
• Function has Vulnerability - what the Resource does
• Resource Interaction has Vulnerability - the exchange between Resources
• Interaction Element has Vulnerability - what is exchanged between Resources
• Resource poses Threat (synonym Hazard)
• Threat exploits Vulnerability
• Threat to Resource
• Threat to Function
• Threat to Resource Interaction
• Threat to Interaction Element
• Threat poses Risk
• Resource exposed to Risk
• Risk is managed by Mitigation
• Mitigation uses Function
• Mitigation uses Resource

By way of a small example using a small subset of the above we have a nuclear reactor.

It is possible to identify an external actor as the origin of the threat (hazard) - ‘Resource 1 poses Threat to Resource 2’. Similarly mitigation might be a result of a part of the same resource or it might require a different one (‘Resource 1 is exposed to Risk is managed by Mitigation uses Resource 2’).

In all of this the description of Risk, Vulnerability, Threat (Hazard) and Mitigation can be linked to the description of the solution or part of the solution. This therefore enables the solution design to be modified in response or the mitigation to be altered in response to a design change so the cause and effect is always visible in the architecture description.

So far all of this is pretty straightforwards. The “toughie” is:-

• Risk is a Event

This is tricky not because there is any doubt that a Risk is a type of Event. A risk typically is associated with a probability of occurrence and an impact severity. If we are thinking about an event in the way it would be used in, say, Fault Tree Analysis (FTA) then it also has a probability of occurrence. It too can have an impact severity. So are there differentiating attributes of a risk (event)? We couldn’t think of any - suggestions welcome. The rationale for having a separate Risk metamodel element was simply that people might expect to see elements labelled as ‘Risk’ because they might not equate ‘Event’ with the description of a risk (affordance and visibility).

Note. Although there isn’t a difference in the attributes there is a distinction in the possible values A Risk and an Event can take. A Risk, by definition is always uncertain but possible therefore 0 < probability of occurrence_Risk < 100% whereas a ‘straight‘ Event may be impossible or certain and therefore 0 ≤ probability of occurrence_Event ≤ 100%. Risk therefore seems to occupy a subset of the range of values for Event.

• Risk caused by Risk
• Risk impacts on Resource
• Risk caused by Resource
• Risk AND / OR / etc. Risk

and this is less clear when Risk and Event are separate entities on the metamodel diagram.

If there was the one element, Event, then it would still allow risks (Events) to be clustered or grouped which would allow the SVp-11 to be used to describe and identify common causal risk (events) and therefore suggest ways in which risks might be managed. The only penalty seems therefore to be 1) visibility - can risks be identified as such when typed as Event? 2) affordance - is it obvious that an Event element can be used to describe a risk?

Can anyone justify why Risk and Event should be distinct or why they should be subsumed into Event? Clearly from a TRAK-management point of view it would be better to apply the Highlander Principle (“there shall only be one”) but this might overridden by the UI / HCI aspects.

Thoughts?

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External Links

• TRAK00001. TRAK. Enterprise Architecture Framework. Viewpoints. 1st January 2016
• TRAK00002. TRAK. Enterprise Architecture Framework. Metamodel. 1st January 2016
• TRAK Metamodel fragment - Safety & Security 1st January 2016 - Wikimedia Commons - https://commons.wikimedia.org/wiki/File%3ATRAK_metamodel_part_2_safety_security.jpg

What Would a TRAK View Look Like in a Graph Database? Part 1

The trouble with using a lot of the enterprise architecture tools is that they were originally developed for software development. This means that they tend to focus on / provide functionality for the expression of objects rather than relationships and they typically use software notation to describe the relations, for example the UML. If you are primarily interested in relationships it is then quite hard to exploit and query the relationships. There is also the inevitable problem with the readability of the result particularly for the non-technical and non-software audience who haven’t grown up with, say, UML Class diagrams.

TRAK is defined in a solution-agnostic way and specifies that all the relationships must be 1) visible; 2) labelled so that the assertions / tuples can be read as simple sentences e.g.

• System. A is configured with B. Software, or
• Argument. D supports Claim. Y

This means that it is easer to read. It is still up to the implementer and the notation (an Architecture Description Language in ISO/IEC/IEEE 42010 terminology) how this appears when visualised. You might, for example, get the following.

This isn’t too bad to read thanks to the TRAK requirements to make everything explicit but if you want to follow relationships and display the results you typically have to dive under the hood create a query that has multiple table joins. Even then the result is a table which isn’t the best way of presenting a structure. If you wanted to recurse down a structure to display something and its parts you might not be able to do this without knowing how many levels you needed to traverse to retrieve the results.

It soon gets all too difficult which is a shame because having created the relationships the real power over a ‘flat’ diagram is the ability to query them to answer questions.

Is there another way? In a nutshell, yes. A TRAK view is defined as a set of assertions / tuples / triples. In mathematical terms these are ‘graphs’ and now you can get graph databases that store graphs rather than tables. It’s therefore a straightforward exercise to create a TRAK view in a graph database using the governing TRAK viewpoint (which constrains what tuples can be shown) and the TRAK metamodel as the ‘domain model’ for reference.

I’m in the process of evaluating the free community edition of the Neo4J graph database. The plan is to create a complete architecture description within Neo4J to show how it might look as a set of graphs. Neo4J is pretty straightforwards and the reference manual, online training and free e-books are valuable. I wanted to produce the equivalent of a TRAK architecture description that is already online so I’m porting the one that was used to support the formal conformance assessment of TRAK against ISO/IEC/IEEE 42010:2011.  This particular TRAK architecture description makes a lot of use of the MVp-04 Assurance Viewpoint since it describes a structured set of claims (of compliance), arguments and evidence.

This has been achieved using the CSV import capability of Neo4J to import the elements and their properties. For example the import of the TRAK requirement elements was achieved using:

LOAD CSV WITH HEADERS FROM “file:///requirements.csv” AS row
CREATE (n:Requirement)
SET n = row,
n.`object ID` = toInt(row.`object ID`),
  n.`AD exchange element owning ID` = row.`AD exchange element owning ID`,
  n.`AD exchange element owning organisation`=row.`AD exchange element owning organisation`,
  n.`reference URL` = row.`reference URL`,
  n.`sequence ID`=toInt(row.`sequence ID`),
  n.`requirement ID`=row.`requirement ID`,
  n.`compliance level` = row.`compliance level`,
  n.`requirement paragraph` = row.`requirement paragraph`,
  n.`requirement scope` = row.`requirement scope`,
  n.`requirement type` = row.`requirement type`,
  n.`requirement priority` = row.`requirement priority`,
  n.name = row.name,
  n.description = row.description,
  n.`requirement owning org` = row.`requirement owning org`,
  n.`element author`= row.`element author`,
  n.`created date` = row.`created date`,
  n.`modified date` = row.`modified date`
SET n :Requirement:`Architecture Description Element`

CREATE CONSTRAINT ON (reqt:Requirement) ASSERT reqt.`object ID` IS UNIQUE

All the different TRAK metamodel elements have been imported similarly and connected together, e.g.

LOAD CSV WITH HEADERS FROM “file:///claim_about_requirement.csv” AS row
MATCH (claim1:Claim {`object ID`: toInt(row.Start_Object_ID)})
MATCH (reqt1:Requirement {`object ID`: toInt(row.End_Object_ID)})
MERGE (claim1)-[r:`about`]->(reqt1)
ON CREATE SET r.`connector ID` = toInt(row.`connector ID`);

CREATE CONSTRAINT ON (conn:`about`) ASSERT conn.`connector ID` IS UNIQUE

TRAK also has elements to represent Architecture View so its easy to relate the elements and the connectors to the view(s) that show them.

In Neo4J queries match patterns (think of these as paths through the underlying architecture description - the sets of tuples). Suppose for example I want to show the structure of the standard itself. Off the top of my head I don’t know how deep the structure is but this doesn’t matter since the Cypher query language allow me to recurse to the bottom.

The query to show the requirement structure is simply:

MATCH (a:Standard {name:'ISO/IEC/IEEE42010:2011 Systems and Software Engineering - Architecture Description'})
MATCH (a) -[r:`has part`*1..]->(b)
RETURN a,b, r

which simply tells Neo4J to start with the topmost node - a TRAK ‘Standard’ and then look for all the outgoing ‘has part’ relationships for as many levels as needed and then return the nodes and relationships. The result of this is shown below.

Display full size image.

Finding orphan nodes with no relationships is as simple as:

MATCH (node)
WHERE NOT ((node)—())
RETURN node;

It’s not yet TRAK-compliant. I’ve still got to figure out how to get the cascading style sheet to display the TRAK metamodel element type (‘label’ in Neo4J) but it’s already a very useful tool to exploit the relationships made. This is with Neo4J out of the box as a bare database i.e. with no application built on top of it. It ought to be relatively straightforwards for a software engineer to extend this to implement the TRAK viewpoint definitions and visually query the database. Or I should add that it is if you’ve got a simple and explicit metamodel because it’s easy to square this with the graphs produced. If all you’ve got is a more indirect and complicated one enforced via a UML profile it’s a much harder task and you can’t then easily verify the result against the original views in the modelling tool.

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Definitions - What Exactly is a Risk Part 2?

In part 1 we established that a lot of the current definitions of risk don’t actually define what a risk is - they simply define a formula for calculating it or prioritising it which doesn’t help us get at what a risk is and therefore whether it is a distinct entity.

The OED has a definition:

(Exposure to) the possibility of loss, injury, or other adverse or unwelcome circumstance; a chance or situation involving such a possibility

Dissecting this with the old semantic scalpel we have parts:

• possibility or chance
• adverse circumstance
• a situation

Possibility or Chance

A risk always has a probability of occurring. This therefore means that the metamodel entity has ‘probability of occurrence’ as an attribute. It also means that there are qualifying values in order for it to be a risk - the probability of occurrence cannot be zero since there is then no possibility and it cannot be 100% either because it is then a certainty not a risk.

Adverse Circumstance

A risk is associated with a harmful outcome (the positive flip side is an opportunity). We can represent this using a relationship between risk (if the vehicle for risk is an event) and hazard (threat).

A Situation

This starts to sound like an event through which the unlucky recipient is exposed to the risk. Is this a risk or is it really a description of a risky-event? 

Much the same thing happens to hazard where at least one definitions defines a hazardous event not a hazard. In IEC 61508:2010 part 4 Hazard is defined as:

potential source of harm [Guide 51 ISO/IEC:1990]

but then add

NOTE – The term includes danger to persons arising within a short time scale (for example, fire and explosion) and also those that have a long-term effect on a person’s health (for example, release of a toxic substance).

which isn’t correct because the release of a toxic substance is not a hazard but a hazardous event. The toxic substance represents the hazard. This is important because we’d represent hazard and hazardous event differently with a relationship between a Hazard and Event and the combination becomes the ‘hazardous event’.

Is something similar happening with risk in common parlance or definitions?

If a Risk is a distinct entity we have:

• Hazard (syn. Threat) poses Risk
• Risk is a Event (where 100 > probability of occurrence > 0)

and we can have

• Hazard (syn. Threat) to Resource (i.e System, Physical, Software, Organisation, Job or Role) 
  

to introduce the required ‘harm’ or ‘adverse circumstance’.

The limits on probability of occurrence have to be applied because if it is 100% it isn’t a possibility it’s a certainty and therefore no longer a risk.  Similarly it cannot be zero because it can never happen and is therefore not a risk.

We could of course just represent a Risk using Event where the value of an attribute ‘probability of occurrence’ takes a value between these limits when representing a risk and is otherwise null or 100% if representing a ‘straight’ Event.

Of course even if it is a type of event there are advantages in making it a distinct entity since as an element in a tool it makes it easy to find, to navigate to or from and to distinguish it from a straight event. This utility might justify it being distinct.

So, is a risk a type of event?

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External Links

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