This document covers the various scoring calculations and methods used across the system for various Asset, Company, and Risk Grade scoring.
Table of Contents
Severity and Risk Scoring Descriptions
Severity
This indicates the seriousness or criticality of a vulnerability. Common severity levels include low, medium, high, and critical. Higher-severity vulnerabilities typically pose a greater risk and require immediate attention and mitigation.
Base Score
A numerical value is assigned to a vulnerability based on its characteristics and potential impact. It is often calculated using a standardized formula, such as the Common Vulnerability Scoring System (CVSS), which considers factors like exploitability, impact, and other metrics.
Impact Score
The Impact Score evaluates the potential impact of a vulnerability on the affected system or organization. It considers factors such as data loss, system compromise, service disruption, regulatory compliance impact, and financial repercuss
Exploitability Score
Indicates the ease with which an attacker could exploit the vulnerability to launch an attack. Factors such as the availability of exploits, complexity of exploitation, and required privileges may contribute to this score.
To see these scores, tap on the CVE-ID and then the Base Score link (be sure you are on the correct CVSS Version).
EPSS Score
Exploit Prediction Scoring System is sourced from first.org/epss.
Download the data/base from here: https://www.first.org/epss/data_stats
EPSS is a daily estimate of the probability of observed exploitation activity over the next 30 days. It is designed from the ground up to make the best use of all of the information available, and it does this in five steps:
Collect as much vulnerability information as we can from a variety of sources
Collect evidence of daily exploitation activity
Train a model: discover/learn the relationship between the vulnerability information and the exploitation activity
Measure the performance of the model, tweak and repeat step 3 to optimize the model
Daily: refresh the vulnerability information (step 1) and use the model (step 3) to produce daily estimates of the probability of exploitation in the next 30 days for each published CVE.
How is Severity Calculated?
Severity information is imported from the standard vulnerability databases.
The Severity score for vulnerabilities is typically derived from the Base Score in the Common Vulnerability Scoring System (CVSS).
The Base Score itself is calculated based on the Exploitability and Impact metrics.
Here's a breakdown of how the Severity score is calculated:
Base Score Calculation
The Base Score in CVSS is calculated using the following formula:
Base Score = (0.6 * Impact) + (0.4 * Exploitability)
Impact: This component of the Base Score represents the potential impact of a successful exploit. It is derived from the Confidentiality Impact (C), Integrity Impact (I), and Availability Impact (A) metrics in CVSS, each of which is scored from 0 to 10.
Exploitability: This component of the Base Score represents the ease of exploitation. It is derived from the Attack Vector (AV), Attack Complexity (AC), Privileges Required (PR), User Interaction (UI), and Scope (S) metrics in CVSS, each of which is scored from 0 to 10.
Severity Mapping
Once the Base Score is calculated and mapped to a predefined Severity level. The mapping is typically as follows:
Base Score 0.0 - 3.9: Low Severity
Base Score 4.0 - 6.9: Medium Severity
Base Score 7.0 - 8.9: High Severity
Base Score 9.0 - 10.0: Critical Severity
These ranges are defined by the CVSS standard and are used to categorize vulnerabilities based on their potential impact and exploitability.
Environmental Metrics
In some cases, environmental metrics such as the Environmental Score (EPSS Score) may also influence the Severity rating. These factors can modify the Base Score to reflect the risk in a particular deployment context.
In summary, the Severity score for vulnerabilities is calculated based on the Base Score, which is, in turn, calculated from the Impact and Exploitability metrics. The Severity score indicates the seriousness of a vulnerability, ranging from low to critical, based on its potential impact and ease of exploitation.
For more information, check these sources out below:
https://nvd.nist.gov/vuln-metrics/cvss
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator
How is EPSS Calculated?
You can find the general calculation on EPSS in the link below:
https://www.cyentia.com/epss-version-2-is-out/
We are calculating using the tool from the below link derived from the above website:
https://epss.cyentia.com/epss_scores-current.csv.gz
Calculation of Vulnerability Risk
ConnectSecure uses CVSS 3.0 as a base system for calculating vulnerability risk. Click here for more information on CVSS calculations: https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator
The Common Vulnerability Scoring System (CVSS) is a free and open industry standard for assessing the severity of computer system security vulnerabilities.
CVSS attempts to assign severity scores to vulnerabilities, allowing responders to prioritize responses and resources according to the threat.
Scores are calculated using a formula that depends on several metrics that approximate the ease of exploitation and its impact. Scores range from 0 to 10, with 10 being the most severe.
While many utilize only the CVSS Base score to determine severity, temporal and environmental scores also exist to factor in the availability of mitigations and the widespread vulnerability of systems within an organization.
Viewing Discovered Vulnerabilities and Scoring Data
Navigate to the Problems module to see the details of discovered vulnerabilities, including their respective Severity, ConnectSecure Score, Base Score (NVD), Impact Score (NVD), Exploitability Score (NVD), and EPSS Score.
NOTE: You may need to adjust your column view/order to match the view above:
ConnectSecure Scoring Calculations
For ConnectSecure, the CVSS maps the vulnerability score to an asset, and then we compute the overall vulnerability score based on the weights of different vulnerabilities.
The following table is used to determine the weightage of each scored category:
Scoring Category | Weightage |
|---|---|
CVSS Base Score | 50% |
CVSS Impact Score | 10% |
CVSS Exploitability Score | 20% |
Asset Importance Score | 10% |
Impact based on actual malware being released | 10% |
Here are the asset importance default values used for the calculations:
Importance | Default Value/Score |
|---|---|
Critical | 100 |
High | 75 |
Medium | 50 |
Low | 25 |
For example:
Vulnerability Maximum BaseScore = 9.8
Vulnerability Maximum Exploitability Score = 3.9
Asset Importance = 25 (for Low)
=>(Vulnerability Maximum BaseScore * 5) + (Vulnerability Maximum exploitabilityScore * 2) + (Asset Importance / 10) * 3
=>(9.8 * 5) + (3.9 * 2) + (25 / 10) * 3
=>49 + 7.8 + 7.5
=>64.3
ConnectSecure's Vulnerability Risk Score for the above example is 64.3.
It’s then computed for each asset, and then we compute a mode and mean and give the higher of the two as a risk score.
Asset Risk Grade Scoring Details
Assets are scored individually and assigned a letter grade: A, B, C, D, E, or F. Tap on the letter grade of any asset to see the Rubrix breakdown of how we score based on vulnerabilities.
Asset Average Risk Score Calculation
The sum of present Problem Category scores divided by the sum of all Severity Problem Category scores + other Problem Category Scores that are present.
The Severity Problem Category refers to the severity-based vulnerability classifications below.
We use these base weights for the Risk Score calculations based on ‘severity.'
Critical Severity Vulnerabilities = .90 (or 90%)
High Severity Vulnerabilities = .80 (or 80%)
Medium Severity Vulnerabilities = .50 (or 50%)
Low Severity Vulnerabilities = .30 (or 30%)
To obtain your asset’s present Problem Category scores, tap on the letter grade, check for the ‘Exists?’ column for a 'Y' and add that Score value up. See below for a sample.
Asset Risk Score is 20
Add up the total Score for any Problem Category where vulnerabilities Exist.
Divide that total by the total Weightage possible, which is the sum of each severity category + any existing custom.
Critical Severity = .9 or 90
High Severity = .8 or 80
Medium Severity = .5 or 50
Low Severity = .3 or 30
The sum of Severity Problem Categories is 250
Asset Risk Score = Total Score / Total Weightage
20 = 250 (Sum of Severity Categories) / 50 (Total Weightage of Problem Categories that Exist)
Improving Asset Risk Score Grade
Please act on the recommendations provided in the Solutions / Remediation Plan.
Update a version of an Application/OS to the latest version.
Uninstall an application that is not supported, e.g., End of Support.
Use EPSS Categorization to decide which actions should be taken on a priority basis first.
Critical and High-category vulnerability will have the highest impact on the grade.
Company Risk Score Details
What is the Company Risk Score?
The Company Risk Score is the sum of all the Max Risk Scores divided by the Total Assets
The Max Risk Score shows the highest possible risk score based on the most severe confirmed vulnerability.
Company Risk Score Grade Factors
Based on the score, the Company Risk Score Grade is displayed with a letter grade, as shown below.
Company Risk Score Grade: A (0 - 40) = Very Low
Company Risk Score Grade: B (40 - 45) = Low
Company Risk Score Grade: C (45 - 60) = Medium
Company Risk Score Grade : D (60 - 75) = High
Company Risk Score Grade: E (75 - 90) = Critical
Company Risk Score Grade: F (90 - 100) = Very Critical
Company Risk Score Grade Descriptions
Risk Score Grade: A (0 - 40) represents Very Low.
Problems are present, and an organization should aim to be in the 0 to 40 range; however, all significant issues have been addressed broadly.
Risk Score Grade: B (40 - 45) represents Low.
Problems are present, and the value ranges from 40 to 45. However, significant issues have been addressed.
Risk Score Grade: C (45 - 60) represents Medium.
A few problems need immediate attention, with the score ranging from 45 to 60.
Risk Score Grade: D (60 - 75) represents High.
Many problems require attention, with a score ranging from 60 to 75.
Risk Score Grade: E (75 - 90) represents Critical.
The network is susceptible to attack and needs remediation; the value ranges from 75 to 90.
Risk Score Grade: F (90 - 100) represents Very Critical.
The network is highly susceptible to attack and needs remediation; the value ranges from 90 to 100.
External Scan Risk Scoring Details
External Assets are configured and scored at the Company level under the Assets > External Assets module. The Results tab displays a table view of any scanned external asset with various scan details.
Tap on the external asset IP to see the details:
Tap directly on the letter grade assigned to see the scoring details:
External Scan Risk Score Calculation
The sum of the Problem Category scores where Exists? is true divided by the sum of all Severity Problem category scores and other Problem Category score(s) if present.
The Severity Problem Category refers to the severity-based vulnerability classifications below.
We use these base weights for the Risk Score calculations based on ‘severity.' The total score for all severity category groups is 250. (90+80+50+30).
Critical Severity Vulnerabilities = .90 (or 90%)
High Severity Vulnerabilities = .80 (or 80%)
Medium Severity Vulnerabilities = .50 (or 50%)
Low Severity Vulnerabilities = .30 (or 30%)
We start all scoring at the total base of 250 (using the above info) and then add any scores based on the problem category showing as Exists? Y in the scoring rubric.
To obtain your asset’s present Problem Category scores, tap on the letter grade, check for the ‘Exists?’ column for a 'Y' and add that Score value up. See below for a sample.
Pay attention to the ‘Exists’ to determine if the ‘Weightage’ is included in the sum calculations.
In the above example, the Asset Risk Score is shown as 60.
Add up the total Score for any Problem Category where vulnerabilities Exist. (260)
2. Divide that by the Sum of all the Severity Problem Category scores + any other Problem Category Score if present)
The sum of the present Problem Category scores is 260
The sum of the Severity Problem Categories plus other present is 430 (250+180)
260 / 430 = .60% or 60
Only the confirmed vulnerabilities and insecure open ports are considered; the filtered ports and other categories are not included in the calculation.
Security and Compliance Report Card Grading
The table values below are used for our Security Report Card and Compliance Report Card grades.
Category | Grades | Description |
Antivirus | 5 | Anti-virus is installed and up to date |
4 | Anti-virus is installed but not up to date | |
1 | Anti-virus is not installed | |
Local Firewall | 5 | Local firewall is enabled for both public and private networks |
4 | Local firewall is not enabled for private networks | |
3 | Local firewall is not enabled | |
1 | Local firewall is not enabled | |
Insecure Listening Ports | 5 | There are no insecure listening ports |
3 | One insecure listening port was detected | |
1 | More than one insecure listening port was detected | |
Failed Login | 5 | No failed interactive logins in the past 7 days |
4 | 7 or fewer failed interactive logins in the past 7 days | |
3 | 14 or fewer failed interactive logins in the past 7 days | |
1 | 15 or more failed interactive logins in the past 7 days | |
Network Vulnerabilities | 5 | No network vulnerabilities |
4 | Low network vulnerabilities found (CVSS < 4.0) | |
3 | Medium network vulnerability found (CVSS >= 4.0) | |
1 | Critical network vulnerability found (CVSS >= 9.0) | |
System Aging | 5 | All computers are less than 2 years old |
4 | Some computers between 3 and 4 years old | |
3 | Some computers between 4 and 7 years old | |
1 | Some computers over 8 years old | |
Supported OS | 5 | All computers have supported Operating Systems |
4 | Some Operating Systems are in extended support | |
3 | Some Operating Systems are within 1 year of end of life | |
1 | Some unsupported Operating System | |
LLMNR | 2 | LLMNR not Allowed |
5 | LLMNR Disabled | |
1 | LLMNR Enabled | |
NBTNS | 2 | NBTNS not Allowed |
5 | NBTNS Disabled | |
1 | NBTNS Enabled | |
NTLMV1 | 2 | NTLMV1 not Allowed |
5 | NTLMV1 Disabled | |
1 | NTLMV1 Enabled | |
SMBV1Server | 2 | SMBV1 Server not Allowed |
5 | SMBV1 Server Disabled | |
1 | SMBV1 Server Enabled | |
SMBV1Client
| 2 | SMBV1 Client not Allowed |
5 | SMBV1 Client Disabled | |
1 | SMBV1 Client Enabled | |
SMB Signing | 2 | SMB Signing Disabled |
5 | SMB Signing Enabled | |
1 | SMB Signing Disabled |
Security Report Card
Compliance Report Card
End of Life (ConnectSecure Score)
ConnectSecure considers EOL a maximum-risk scoring event since the application no longer receives security updates.
ConnectSecure checks against Assets to categorize end-of-life (EOL) in two ways.
OS-OUT-OF-SECURITY-SUPPORT
OS-OUT-OF-ACTIVE-SUPPORT
ConnectSecure Score (cs score) will display the same as NVD Base Score for any confirmed problem that is not classified as END OF LIFE.
Risk Level Descriptions for EOL on Active/Security Support
Level | Description |
|---|---|
1 | Both Active and Security Support have ended; no support is available |
3 | If the operating system is within 1 year of its security support end date; limited support |
4 | If the operating system is within its Active support but past its Security support; extended support |
5 | If the operating system is within both Active and Security support timelines; full support |
Calculation of Vulnerability Risk
ConnectSecure uses CVSS 3.0 as a base system for calculating vulnerability risk. Click here for more information on CVSS calculations: https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator
The Common Vulnerability Scoring System (CVSS) is a free and open industry standard for assessing the severity of computer system security vulnerabilities.
CVSS attempts to assign severity scores to vulnerabilities, allowing responders to prioritize responses and resources according to the threat.
Scores are calculated using a formula that depends on several metrics that approximate the ease of exploitation and its impact. Scores range from 0 to 10, with 10 being the most severe.
While many utilize only the CVSS Base score to determine severity, temporal and environmental scores also exist to factor in the availability of mitigations and the widespread vulnerability of systems within an organization.
Viewing Discovered Vulnerabilities and Scoring Data
Navigate to the Vulnerabilities module to see the details of discovered vulnerabilities, including their respective Severity, Base Score, Impact Score, Exploitability Score, and EPSS Score.
Tap on the Problem Name link to see additional scoring details from the source:
Need Support?
Contact our support team by sending an email to support@connectsecure.com or by visiting our Partner Portal, where you can create, view, and manage your tickets.
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