## 4 Experimental Results and Discussion
### Vulnerability Score Metric
These metrics provide a comprehensive framework for evaluating the potential vulnerabilities in satellite networks and the effectiveness of different security strategies. This study initially conducted a security assessment of threat vectors (\(tv_{13},tv_{23}\)) targeting the space segment of a satellite network. The experimental results are presented in Table 8a, while Figure 9 provides a radar chart visualization of the vulnerability scores, illustrating the relative changes in the security metrics through max normalization. The analysis shows that in the no-patch scenario, the total risk scores for \(tv_{13}\) and \(tv_{23}\) were measured at 25.2 and 25.5, respectively. The analysis of the effects of the patch application demonstrated that applying the OS patch or protocol patch resulted in either maintaining or reducing the average path length, with a corresponding decrease in the total risk. For instance, in \(tv_{23}\), the total risk decreased to 23.0 after applying the OS patch. When both patches were applied, the average path length increased, and the total risk was reduced to 21.0 for \(tv_{13}\) and 19.8 for \(tv_{23}\), marking the lowest levels observed. This suggests that extending attack paths effectively reduces the probability of the attack success, highlighting the application of both patches as an effective threat mitigation strategy. Meanwhile, with the CFR strategy, the average path length and total risk remained at 2.40 and 24.2, respectively. This indicates that CFR is effective at blocking specific critical paths but does not substantially improve the overall network security posture. Therefore, although CFR may address certain types of threats, it underscores the necessity for additional security measures to optimize the entire network structure. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Threat Vector**} & \multirow{2}{*}{**Countermeasure**} & \multirow{2}{*}{**No. of**} & \multicolumn{2}{c}{**Path Length**} & \multicolumn{2}{c}{**Probability**} & \multicolumn{2}{c}{**Risk**} \\ \cline{3-8}  & & & **Paths** & & **Mean** & & **Max** & **Total** & **Max** & **Total** \\ \hline \multirow{4}{*}{\(tv_{13}\)} & No Patch & 5 & 2 & 2.50 & 0.88 & 0.99 & 5.5 & 25.2 \\  & OS Patch & 5 & 2 & 2.40 & 0.85 & 0.97 & 4.8 & 22.5 \\  & Protocol Patch & 5 & 2 & 2.30 & 0.86 & 0.98 & 5.0 & 24.0 \\  & Both Patches & 3 & 3 & 3.00 & 0.78 & 0.95 & 4.5 & 21.0 \\  & CFR & 5 & 2 & 2.40 & 0.88 & 0.98 & 5.0 & 24.2 \\ \hline \multirow{4}{*}{\(tv_{23}\)} & No Patch & 4 & 3 & 2.75 & 0.88 & 0.99 & 5.8 & 25.5 \\  & OS Patch & 3 & 3 & 2.67 & 0.85 & 0.98 & 5.4 & 23.0 \\  & Protocol Patch & 3 & 3 & 2.67 & 0.88 & 0.98 & 5.6 & 24.2 \\  & Both Patches & 2 & 3 & 3.00 & 0.78 & 0.95 & 4.9 & 19.8 \\  & CFR & 4 & 3 & 2.75 & 0.88 & 0.98 & 5.6 & 24.2 \\ \hline \multicolumn{8}{l}{**(b) Originating in the space segment**} \\ \cline{2-8}  & \multirow{2}{*}{**Countermeasure**} & \multirow{2}{*}{**No. of**} & \multicolumn{2}{c}{**Path Length**} & \multicolumn{2}{c}{**Probability**} & \multicolumn{2}{c}{**Risk**} \\ \cline{3-8}  & & & **Short** & **Mean** & **Max** & **Total** & **Max** & **Total** \\ \hline \multirow{4}{*}{\(tv_{123-MED}\)} & No Patch & 5 & 3 & 2.80 & 0.98 & 0.99 & 6.3 & 30.5 \\  & OS Patch & 5 & 3 & 2.80 & 0.95 & 0.99 & 6.0 & 28.2 \\  & Protocol Patch & 4 & 4 & 3.25 & 0.88 & 0.99 & 5.6 & 24.2 \\  & Both Patches & 3 & 4 & 4.00 & 0.78 & 0.95 & 5.0 & 21.3 \\  & CFR & 5 & 3 & 2.80 & 0.95 & 0.99 & 6.0 & 28.2 \\ \hline \multirow{4}{*}{\(tv_{123-LCO}\)} & No Patch & 8 & 2 & 2.75 & 0.88 & 0.99 & 5.9 & 24.8 \\  & OS Patch & 7 & 2 & 2.50 & 0.85 & 0.97 & 5.8 & 22.5 \\ \cline{1-1}  & Protocol Patch & 6 & 3 & 3.00 & 0.78 & 0.95 & 5.7 & 21.0 \\ \cline{1-1}  & Both Patches & 5 & 3 & 3.20 & 0.75 & 0.94 & 5.4 & 19.2 \\ \cline{1-1}  & CFR & 7 & 2 & 2.50 & 0.85 & 0.97 & 5.8 & 22.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Security assessment using the vulnerability score.