Establish Assessment Scope
The first step in CTSA is to establish the scope of the evaluation, which can be characterized in terms of:
- The set of system assets being evaluated
- The range of attack TTPs being considered
- The types of adversaries
Black Kite establishes the assessment scope during the asset discovery process, which discovers all publicly visible accessible domains, subdomains, IP/CIDR ranges, etc.
Identify Candidate TTP
Once the scope of CTSA is established, the next step is to evaluate the cyber asset’s architecture, technology, and security capabilities against TTPs in the Mission Assurance Engineering (MAE) Catalog. Unclassified sources of adversary TTPs in the catalog include MITRE-hosted resources such as Common Attack Pattern Enumeration and Classification (CAPEC), Common Weakness Enumeration (CWE), and Common Vulnerability Enumeration (CVE). CAPEC is a compilation of attack patterns derived from specific real-world incidents. CWE is a catalog of software weaknesses and defects that adversarial TTPs may exploit. CVE catalogs vulnerabilities found in Commercial off-the-shelf (COTS) hardware and software products.
Eliminate Implausible TTPs
This initial set of candidate TTPs undergoes a narrowing process to eliminate TTPs considered implausible. Several factors can make a TTP an implausible method of a cyber attack. Many TTPs have prerequisites or conditions that must hold true in order for that TTP to be effective.
Apply Scoring Model
Candidate TTPs that cannot be eliminated are ranked using a scoring model. The TTP scoring model assesses the risk associated with each TTP relative to the other 10 plausible TTPs considered in the assessment. This ranking helps set priorities on where to apply security measures to reduce the system’s susceptibility to cyber-attack. CAPEC severity levels, CVSS scores, and CWE severity ranks are the main parameters to calculate the TTP risk scores.
Construct a Threat Matrix
CTSA produces a Threat Matrix, which lists plausible attack TTPs ranked by decreasing risk score and their mapping to cyber assets as a function of adversary type. Black Kite has over 500 TTPs (APPSEC001, APPSEC002, … DNS001, DNS002,… etc.) with different risk scores.
The Black Kite threat matrix is calculated by using the Common Weakness Scoring System (CWSS™) that provides a mechanism for prioritizing software weaknesses in a consistent, flexible, open manner. It is a collaborative, community-based effort that is addressing the needs of its stakeholders across government, academia, and industry. When used in conjunction with the Cyber Threat Susceptibility Assessment (CTSA) or Common Weakness Risk Analysis Framework (CWRAF™), organizations are able to apply CWSS to those CWEs that are most relevant to their own specific businesses, missions, and deployed technologies.
The Grading Scale Table
Once the category grades are calculated based on the equation given above, the grades are translated into GPA and Letter grades based on the American Grading system. Below is a grading system used by Black Kite.
The category grades are calculated once assessments on all the categories are completed. Each category has a different weight in the overall grade as shown below.
|Category Name||Weight (Total 100)||Category Name||Weight (Total 100)|
|Digital Footprint||0/100||IP Reputation||7/100|
|DNS Health||6/100||Hacktivist Shares||5/100|
|Email Security||6/100||Social Network||3/100|
|SSL/TLS Strength||6/100||Attack Surface||4/100|
|Application Security||9/100||Brand Monitoring||3/100|
|DDoS Resiliency||4/100||Patch Management||10/100|
|Network Security||6/100||Web Ranking||2/100|
|Fraudulent Domains||5/100||Information Disclosure||3/100|
|Fraudulent Apps||3/100||Website Security||6/100|
|Credential Management||9/100||CDN Security||3/100|
The overall grade is calculated by the weighted arithmetic mean, which is similar to an ordinary arithmetic mean (the most common type of average), except that instead of each of the data points contributing equally to the final average, every category contributes proportionally with the weights.
So the final grade is calculated by:
TheOverAllGPA = Sum(TheGPAofTheCategory * WeightOfTheCategory)
The overall GPA is translated to letter grade and percent again using the same table (The Grading Scale Table) given above.
Black Kite has analyzed data in different risk categories from 1,000,000 servers for hundreds of companies and calculated letter grades for the results. For example, a grade of ‘B’ indicates an organization has opened the door to a sophisticated hacker, a grade of ‘F’ means hackers of all types are being invited. The overall grade of the cyber risk scorecard shows “How easy is it to hack the corresponding environment?”.