CWE-501: Trust Boundary Violation

What is Trust Boundary Violation?

• Overview: Trust Boundary Violation occurs when a program improperly mixes trusted and untrusted data, leading to potential mishandling or misinterpretation of unvalidated data by the system.

• Exploitation Methods:

• Attackers can exploit this vulnerability by injecting malicious data into the untrusted portion, which might be treated as trusted.
• Common attack patterns include manipulating data inputs to bypass validation checks or injecting harmful payloads that blend with trusted data.

• Security Impact:

• Direct consequences include unauthorized access, data corruption, or execution of malicious code.
• Potential cascading effects can involve further system compromise, data breaches, or loss of data integrity.
• Business impact may include financial loss, damage to reputation, and legal liabilities due to non-compliance with data protection regulations.

• Prevention Guidelines:

• Specific code-level fixes include ensuring that data is always validated before crossing the trust boundary and separating trusted and untrusted data structures.
• Security best practices involve implementing strict input validation and using whitelisting approaches where possible.
• Recommended tools and frameworks include static analysis tools to detect trust boundary violations and security frameworks that enforce data validation policies.

Corgea can automatically detect and fix Trust Boundary Violation in your codebase. [Try Corgea free today](https://corgea.app).

Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

JavaScript Example

// This code demonstrates a Trust Boundary Violation vulnerability.
// User input is directly merged with trusted data in the same object without validation.

function processUserData(userInput) {
    // Mixing trusted configuration data with untrusted user input
    const config = {
        adminEmail: "admin@example.com",
        accessLevel: "user",
        ...userInput // Potentially malicious data is mixed into a trusted object
    };

    // Assuming the entire config object is trusted and performing operations
    if (config.accessLevel === 'admin') {
        console.log("User has administrative access.");
    } else {
        console.log("User has regular access.");
    }
}

// Simulating user input
processUserData({ accessLevel: 'admin' }); // Untrusted user input can escalate privileges

In this vulnerable example, user input is directly mixed into a trusted configuration object without validation. This allows an attacker to escalate privileges by manipulating the accessLevel.

How to fix Trust Boundary Violation?

To fix a Trust Boundary Violation, you must clearly separate trusted data from untrusted data. This can be achieved by validating and sanitizing user input before it is used alongside trusted data. Here are the steps to fix this issue:

1. Validate Input: Always validate user input to ensure it adheres to expected formats and values.
2. Explicitly Define Trust Boundaries: Do not directly mix user input with sensitive or trusted data structures. Keep them separate until input is verified.
3. Sanitize Input: Remove or neutralize potentially harmful parts of user input before using it.
4. Use Whitelisting: Prefer using whitelisting (allowing known good values) over blacklisting (blocking known bad values).

Fixed Code Example

// Fixed code by separating trusted and untrusted data and validating input.

function processUserData(userInput) {
    // Trusted configuration data
    const config = {
        adminEmail: "admin@example.com",
        accessLevel: "user"
    };

    // Validate and sanitize user input before using it
    const validatedInput = validateAccessLevel(userInput.accessLevel);

    // Use validated input separately
    if (validatedInput === 'admin') {
        console.log("User has administrative access.");
    } else {
        console.log("User has regular access.");
    }
}

// Function to validate and sanitize user input
function validateAccessLevel(accessLevel) {
    const allowedAccessLevels = ['user', 'admin'];
    return allowedAccessLevels.includes(accessLevel) ? accessLevel : 'user';
}

// Simulating user input
processUserData({ accessLevel: 'admin' }); // Validation ensures only allowed access levels

In the fixed code, we introduced a validateAccessLevel function to ensure that only predefined access levels are allowed. By separating trusted data from user input and validating it before use, we maintain the integrity of the trust boundary and prevent privilege escalation.