Vulnerability Response Rollup Calculators

Release version: Washingtondc

Updated February 6, 2024

4 minutes to read

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Summary of Vulnerability Response Rollup Calculators

The Vulnerability Response Rollup Calculators in the Washingtondc release allow users to configure how cumulative risk scores are computed for remediation tasks and imported vulnerabilities. These calculators play a vital role in assessing and managing risk effectively within an organization.

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Key Features

Remediation Task Rollup: Aggregates risk scores for all vulnerable items in a remediation task for an overall risk score.
Patch Update Rollup: Compiles risk scores for vulnerable items associated with the same patch update.
Organization Risk Score Rollup: Combines risk scores from various vulnerable items across the organization into a unified risk score displayed on a dashboard.
Vulnerable Item Rollup: Consolidates risk scores for host vulnerable items to contribute to the organization's overall risk score.
Vulnerability Entry Rollup: Totals risk scores for items related to the same vulnerability entry.
Rollup EPSS Scores from NVD to TPEs: Integrates EPSS scores for vulnerabilities to estimate the likelihood of exploitation.
Remediation Effort Rollup: Combines risk scores from all records in a remediation effort to provide an overall risk score.

Key Outcomes

By configuring rollup calculators, users can assign weights to various computed values, affecting how the cumulative risk score is determined for vulnerabilities and remediation tasks. The calculators run scheduled jobs every 15 minutes to update risk scores based on any changes, ensuring that users have the most current risk assessments available.

For example, in a remediation task with multiple vulnerabilities, users can calculate an overall risk score using a weighted formula, allowing for more informed decision-making regarding risk management. Additionally, understanding the probability of at least one vulnerability being exploited helps organizations assess their overall threat landscape more accurately.

After your initial assessment of risk calculators in the Setup Assistant, use the vulnerability rollup calculators to configure how the cumulative risk score is computed for remediation tasks and imported vulnerabilities.

Use the vulnerability rollup calculators to configure how the cumulative risk score is computed for remediation tasks and imported vulnerabilities. The following rollup calculators are shipped with the base system:

Remediation Task Rollup: Rolls up the risk scores for all vulnerable items in a remediation tasks, to provide an overall risk score for the entire group of vulnerable items.
Patch Update Rollup: Rolls up the risk scores for all vulnerable items with same patch update, to provide an overall risk score for the patch update.
Organization Risk Score Rollup: Rolls up the risk scores for all host vulnerable items, application vulnerable items, container vulnerable items and configuration issues in an organization, to provide an overall risk score for the entire organization in unified dashboard.
Note:
Starting with v22.0 of Vulnerability Response, you can configure rollup weights for organizational score. Also, individual roll-up calculators have been removed.
Vulnerable Item Rollup: Rolls up the risk scores for all host vulnerable items in an organization, to contribute to the overall risk score of the entire organization for unified dashboard.
Vulnerability Entry Rollup: Rolls up the risk scores for all vulnerable items with the same vulnerability entry, to provide an overall risk score for the vulnerability entry.
Rollup EPSS Scores from NVD to TPEs: Rolls up the EPSS scores for all vulnerable items/ CVEs listed on the NVD table to existing TPEs, to provide an overall probability of the vulnerability being exploited.
Remediation Effort Rollup: Rolls up the risk scores for all the records in a remediation effort, to provide an overall risk score for the remediation effort.

Navigate to All > Vulnerability Response > Administration > Vulnerability Rollup Calculator.

Configure the rollup calculator to specify how much weight to give each of those computed values in setting the cumulative risk score. The higher the weight, the more that value is used to determine the rolled up risk score in the vulnerability or remediation tasks.

Note:

When Include deferred is selected, all deferred vulnerable items are included in the rollup calculation for the remediation tasks. Be sure that you understand the impact on the total calculation before selecting this option.

Rollup calculators run the scheduled job, Rollup vulnerable item values to vulnerability and groups, every 15 minutes to pick up changes and roll up the details and risk scores to remediation tasks and vulnerabilities. These scheduled jobs also calculate cumulative values for the number of VIs, maximum risk score, remediation target date, and status for remediation tasks.

Note:

Calculated values for vulnerability entries do not include remediation target data.

The risk score is calculated when:

The risk score, remediation target, remediation status, or vulnerability changes on the vulnerable items.
The vulnerable item state changes to Open, Deferred, Closed, or changes from Closed or Deferred.
Vulnerable items are deleted.
Vulnerable items are added or removed from the remediation task.

Vulnerability rollup calculator example: Consider a remediation task VUL324567, which has the following vulnerable items:

VIT1001 with risk score of 30
VIT1002 with risk score of 40
VIT1003 with risk score of 50

Also, consider the following weights in the vulnerability rollup calculator:

Maximum risk score: 80
Average risk score: 5
Count of vulnerable items: 15

Vulnerability rollup calculator example with a maximum risk score of 80, an average risk score of 5, and a count of vulnerable items of 15. — Figure 1. Vulnerability rollup calculator example

In the Vulnerability rollup calculator example, the formula for determining the remediation task Risk Score is:

(Maximum risk score/100) * 80 + (Average risk score /100) * 5 + (factor * 15)

The factor is determined as follows:


VI count	Factor
<10	0.2
10-100	0.4
101-1000	0.6
1001-10000	0.8
> 10000	1

So, for the remediation task, VUL324567:

Average risk score is 40
Maximum risk score is 50
50 (Maximum risk score)
Factor is 0.2

The Risk Score would be 45 [(50/100) * 80 + (40/100) * 5 + 0.2 * 15 = 40 + 2 + 3 = 45]

EPSS rollup calculator script. — Figure 2. Rollup EPSS Scores from NVDs to TPEs

EPSS Rollup calculator - Example

For example, consider an organization with 100 vulnerabilities, each with a 5% chance of being exploited. The question of great interest to a network defender might be: what is the probability that at least one of those vulnerabilities will be exploited, and therefore what is my overall threat? The probability of at least one event occurring is simply the complement (opposite) of no events occurring, that is:

P(at least one exploited vulnerability) = 1 - P(no vulnerabilities are exploited)

Where, the probability of no vulnerabilities is the linear product of each vulnerability not being exploited. In this example, since each vulnerability has a 5% chance of being exploited, they each have a 95% chance of not being exploited. And since there are 100 of them, we can write this as:

P(at least one vuln exploited) = 1 - P(no vulns are exploited) = 1 - P(one vuln not exploited)^100 = 1 - 0.95^100 = 0.994

Which says that the probability of at least one of the vulnerabilities being exploited is 99.4%.

Important:

To modify the Rollup EPSS Scores from NVD to TPEs, you need to switch the Form context menu view to Rollup Developer View from the Default view.