What Is Flaw Hypothesis Methodology?

May 6, 2025

What Is Flaw Hypothesis Methodology?

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The flaw hypothesis methodology is a technique used to predict and analyze flaws in software systemsIt involves compiling a list of potential flaws based on a system’s documentation and specifications.

DEFINITION:

System analysis and penetration technique in which the specification and documentation for an information system are analyzed to produce a list of hypothetical flaws. This list is prioritized on the basis of the estimated probability that a flaw exists, on the ease of exploiting it, and on the extent of control or compromise it would provide. The prioritized list is used to perform penetration testing of a system.
SOURCE: CNSSI-4009

Flaw Hypothesis Test Vulnerability Cyber Risk Assessment cybersecurity best practices
EXAMPLE:

A “Flaw Hypothesis Methodology” example might include the following.  A penetration tester analyzes a web application by first thoroughly reviewing its design and code to identify potential vulnerabilities. Next, he may forming specific hypotheses about where flaws might exist (like insecure input validation or improper session management). Finally, he may try testing those hypothesized flaws to see if they can be exploited. This is essentially “guessing” where vulnerabilities might be based, then verifying them through testing. This process is often used in security assessments to proactively identify potential security risks in a system. 

Key steps in a Flaw Hypothesis Methodology 

Information Gathering:
A detailed review of the system’s documentation, code, architecture, and functionality to understand how it works and identify potential weak points.
Flaw Hypothesis:
Based on the gathered information, the tester creates a list of potential vulnerabilities or flaws they believe might exist within the system, considering common vulnerabilities seen in similar systems. (See below methodology of hypothesis)
Flaw Testing:
Actively testing the system by attempting to exploit the hypothesized flaws, using various tools and techniques to validate if the vulnerabilities are real and exploitable.
Flaw Generalization:

If a vulnerability is found, the tester tries to identify other similar vulnerabilities in the system based on the same underlying flaw, expanding the scope of the testing. 

SAMPLE SCENARIO:
System:
An online shopping website
Information Gathering:
Review the website code to see if user input is directly used in a database query without any sanitization.
Flaw Hypothesis:
“User input is not properly validated before database inquiries, making the website vulnerable to SQL injection attacks.”
Flaw Testing:
Tester attempts injecting malicious SQL code into the website’s search bar to retrieve sensitive database information.
Flaw Generalization:
If the SQL injection is successful, a tester can look for other input fields on the website, and focus on similar unvalidated, exploitable user input with the same vulnerability. 

See NIST Testing Documentation

What is the methodology of hypothesis?