Assets are tangible objects of value to stakeholders. By defining an asset in CAIRIS, we implicitly state that this needs to be secured in light of risks which subsequently get defined.
Assets are situated in one or more environments. Security and Privacy properties are associated with each asset for every environment it can be found in. These properties are described below:
|Confidentiality||The property that information is not made available or disclosed to unauthorised individuals, entities, or processes.||ISO/IEC 27001|
|Integrity||The property of safeguarding the accuracy or completeness of assets.||ISO/IEC 27001|
|Availability||The property of being accessible and usable on demand by an authorised entity.||ISO/IEC 27001|
|Accountability||The property that ensures the actions of an entity may be traced uniquely to an entity.||ISO 7498-2|
|Anonymity||The property that other users or subjects are unable to determine the identity of a user bound to a subject or operation.||Common Criteria Privacy Requirements|
|Pseudonymity||The property that a set of users and/or subjects are unable to determine the identify of a user bound to a subject or operation, but that this user is still accountable for its action.||Common Criteria Privacy Requirements|
|Unlinkability||The property that users and/or subjects are unable to determine whether the same user caused certain operations in the system.||Common Criteria Privacy Requirements|
|Unobservability||The property that users and/or subjects cannot determine whether an operation is being performed.||Common Criteria Privacy Requirements|
Each of these properties is associated with the value of None, Low, Medium, or High. The meaning of each of these values can be defined in CAIRIS from the Asset Values dialog; this is available via the Options/Asset values menu.
Adding, updating, and deleting an asset¶
- Select the Risks/Assets menu button to open the assets table, and click on the Add button to open a new asset form.
- Enter the name of the asset, a short code, description, and significance. The short-code is used to prefix requirement ids associated with an environment.
- If this asset is deemed critical, click on the Criticality tab, and click on the Critical Asset check-box. A rationale for declaring this asset critical should also be added. By declaring an asset critical, any risk which either threatens or exploits this asset will be maximised until the mitigations render the likelihood of the threat or the severity of the vulnerability inert.
- Click on the Add button in the asset table, and select an environment to situate the asset in. This will add the new environment to the environment list.
- After ensuring the environment is selected in the environment table, add the security properties to this asset for this environment. Security properties are added by clicking on the Add button in the properties table to open the Choose security property dialog. From this window, a security property, its value its value rationale can be added.
- Click on the Create button to add the new asset.
- Existing assets can be modified by double clicking on the asset in the Assets dialog box, making the necessary changes, and clicking on the Update button.
- To delete an asset, select the asset to delete in the assets table box, and select the Delete button. If any artifacts are dependent on this asset then a dialog box stating these dependencies are displayed. The user has the option of selecting Yes to remove the asset dependencies and the asset itself, or No to cancel the deletion.
Understanding how assets can be associated with each other is a useful means of identifying where the weak links in a prospective architecture might be. CAIRIS supports the association of assets, inconsistency checking between associated assets, and visualisation of asset models.
The CAIRIS asset model is based on UML class models. Asset models can be viewed for each defined environment. As well as explicitly defined asset associations, asset models will also contain associations implicitly defined. For example, if a task has been defined, and this task concerns within an environment contain one or more assets, then the participating persona will be displayed as an actor, and an association between this actor and the asset will be displayed. Additionally, if concern associations have been defined between goals and assets and/or associations then zooming into the model will display these concerns; the concerns are displayed as blue comment elements.
Adding an asset association¶
- You can add an association between assets by selecting the Risk/Asset Association menu, and clicking on the Add button in the association table.
- In the association form which is opened., set the adornments for the head and tail end of the association. Possible adornment options are Inheritence, Association, Aggregation, and Composition; the semantics for these adornments are based on UML.
- Set the multiplicity (nry) for the head and tail ends of the
association. Possible multiplicity options are
- Optional role names can also be set at the head or tail end of the association.
- Select the Create (or Update if modifying an existing association) will add the association to the CAIRIS model.
- You can also add associations between other assets from the environment Associations tab within the Asset form. You can add a new association by clicking on the Add button in the association table to open the association form. From this form, you can add details about the nature of the association between the asset you’re working on and another [tail] asset. Once you click on Update, the association will be added to your working object, but won’t be committed to the model until you click on the Update/Create button.
Although not possible from the GUI, it is possible to add associations between assets directly in a CAIRIS model file without first defining security or privacy properties for the asset in the model file. If you do this, all the security and privacy properties for the asset are set to None and the rationale of
Implicit is set for each property.
Viewing Asset models¶
Asset models can be viewed by selecting the Models/Asset menu, and selecting the environment to view the environment for.
By changing the environment name in the environment combo box, the asset model for a different environment can be viewed. The model can be filtered by selecting an asset. This will display on the asset, and the other asset model elements immediately associated with it. By default, concern associations are hidden. These are UML comment nodes that indicate elements from other CAIRIS models associated with asset. These concerns can be shown by changing the Hide Concerns combo box value to Yes.
By clicking on a model element, information about that artifact can be viewed.
For details on how to print asset models as SVG files, see Generating Documentation.
You can specify libraries of template assets that you might form the basis of security or architectural patterns.
These can be added, updated, and deleted in much the same way as standard assets, but with two differences:
- Template assets are not environment specific, so you need to specify the general security properties that need to be protected should this asset be included in a model.
- You need to first define Access Rights, Surface Types, and Privileges.