DEXi representation Sample Clauses

DEXi representation. In the DEXi model, a risk node has two sub-nodes, one representing the likelihood and one representing the consequence for the asset in question. Figure 19 shows the DEXi-representation of the CORAS fragment shown in Figure 18, where R1 represents the risk, l_U1 represents the likelihood of the incident U1, and c_U1_A1 represents the consequence of U1 for asset A1. Notice that in the CORAS diagram, the risk does not have a separate name as it is not represented by a separate node, but by the combination of the incident, the asset and the relation between them. Moreover, although the number/index is identical for the risk, the incident, and the asset in this particular example, this need not necessarily be the case.

DEXi representation. Figure 23 shows a DEXi fragment used to trigger a proposal for implementing mitigation M1. Figure 23 DEXi fragment for triggering a mitigation proposal The scale of the root node M1 has only two steps: No and Yes. If the value is Yes, this means that the system should propose M1 as a mitigation option (possibly one among many). This should only be done if the following holds:

DEXi representation. Figure 24 shows a DEXi fragment corresponding to the CORAS fragment in Figure 23. Figure 24. DEXi fragment representing a node with attached indicators Here, there is one direct sub-node (which is also a leaf-node, and hence shown as a triangle) to the root node for each attached indicator. Hence, the likelihood of the root node (l_S1) depends on these indicators. Before the utility function of l_S1 can be defined, an ordered scale has to be defined for each indicator. Although the indicators do not necessarily represent a likelihood, we make sure to define the scale in such that a low value implies a low risk contribution. For example, assume that a threat scenario representing initiation of a HTTP Request/Response splitting is included in a risk model for client-server protocol manipulation. To this threat scenario, we attach the indicator 'Has any network reconnaissance attempt been detected in the past?' Since this is a yes/no question, the scale for the indicator only has two steps: Yes and No. A positive answer may indicate that someone has tried to prepare for an attack, and hence an increased likelihood. Therefore, for this indicator scale, the order from lowest to highest value would be No; Yes.

DEXi representation. Figure 28 shows a DEXi fragment used to trigger a proposal for implementing mitigation M1.