Differences Between Static Code Analysis, Pen Testing, and Threat Analysis in JavaScript

When building software, ensuring security is paramount, especially when working with a widely used language like JavaScript. To achieve this, developers and security teams use various techniques, each targeting specific aspects of code security. In this post, we’ll explore the differences between static code analysis, penetration testing (pen testing), and threat analysis, using JavaScript code as a practical example.

1. Static Code Analysis

Static Code Analysis involves analyzing the source code without executing it. This method identifies potential vulnerabilities, bugs, or performance issues early in the development process. The analysis is performed by automated tools that scan through the codebase to find issues based on predefined rules.

What it Does:

• Looks for insecure patterns, improper use of functions, or vulnerabilities like SQL injections, buffer overflows, or cross-site scripting (XSS).
• Identifies best practice violations (e.g., poor error handling, lack of input validation).
• Highlights syntax errors and unused variables.

Example in JavaScript:

let userInput = "<img src=x onerror=alert(1)>";  // Untrusted input
document.getElementById("output").innerHTML = userInput;

Here, an attacker could exploit this vulnerability for cross-site scripting (XSS) attacks. Static code analysis tools like ESLint with security plugins (e.g., eslint-plugin-security) can flag this as a potential issue.

Static Code Analysis Tools for JavaScript:

• ESLint
• SonarQube
• JSHint
• Snyk Code

Pros:

• Quick to run and can be integrated into CI/CD pipelines.
• Provides immediate feedback to developers.
• Detects common vulnerabilities early in the development cycle.

Cons:

• Cannot find runtime issues.
• May produce false positives (flagging non-issues).

2. Penetration Testing (Pen Testing)

Penetration testing (commonly known as pen testing) is a security testing method where testers simulate real-world attacks on an application to find vulnerabilities. Unlike static code analysis, pen testing involves executing the application to see how it responds to various attack vectors.

What it Does:

• Simulates real-world attack scenarios, testing how an attacker might exploit vulnerabilities in the live environment.
• Finds issues that may not be detectable by simply scanning the source code.
• Focuses on both front-end and back-end vulnerabilities, such as SQL injection, cross-site request forgery (CSRF), or insecure API endpoints.

Example in JavaScript:

fetch("/api/update-user", {
    method: "POST",
    body: JSON.stringify({ username: "new_user", role: "admin" }),
    headers: { "Content-Type": "application/json" }
});

A penetration tester could try to manipulate the request body to elevate privileges (e.g., setting role: "admin" to gain unauthorized access).

Pros:

• Tests the entire application stack, including third-party services and configurations.
• Finds security weaknesses in the real-world execution of the application.
• Simulates how an actual attacker might behave.

Cons:

• Requires more time and expertise than static code analysis.
• Typically performed later in the development cycle, when changes are more costly.
• Can miss code-specific vulnerabilities if not combined with static analysis.

3. Threat Analysis

Threat analysis (also known as threat modeling) is a proactive approach where the goal is to identify potential threats or risks to the system before they become actual problems. It involves understanding how attackers might exploit various vulnerabilities in the application and designing defenses to mitigate these threats.

What it Does:

• Identifies potential attack vectors, like unauthorized access or data leakage.
• Maps out all the assets, entry points, and possible attack scenarios.
• Helps design the system architecture to minimize security risks from the outset.

Example in JavaScript:

Suppose you are building an e-commerce site using JavaScript and back-end services. A threat analysis may outline:

• Sensitive data exposure: Users’ payment information could be compromised if the API isn’t secured with HTTPS.
• Authentication threats: Weak passwords or a lack of multi-factor authentication (MFA) could be exploited.

Pros:

• Helps prevent vulnerabilities from being introduced in the design phase.
• Informs developers and architects about potential risks throughout the application’s lifecycle.
• Can guide security-focused development.

Cons:

• Requires security expertise and detailed system knowledge.
• Can be difficult to cover all potential threats.
• More of a preventive measure, so it may not address runtime vulnerabilities directly.

Key Differences

Aspect	Static Code Analysis	Penetration Testing	Threat Analysis
Timing	Early in development (pre-execution)	After deployment or during testing	Before development and during design
Execution	Analyzes code without running the program	Involves running and attacking the application	Focuses on identifying risks and attack vectors
Primary Focus	Code quality and known vulnerabilities	Real-world attack simulation	Identifying threats and designing mitigation strategies
Examples of Tools	ESLint, SonarQube, Snyk	OWASP ZAP, Burp Suite, Metasploit	STRIDE, OWASP Threat Dragon
Strengths	Fast feedback, prevents common mistakes	Finds runtime and