CWE-144: Improper Neutralization of Line Delimiters

What is Improper Neutralization of Line Delimiters?

• Overview: CWE-144, Improper Neutralization of Line Delimiters, occurs when software does not correctly handle special elements that could be understood as line delimiters, leading to unintended behaviors when data is processed by another component.

• Exploitation Methods:

• Attackers can exploit this vulnerability by injecting unexpected line delimiters into data streams, causing the receiving system to misinterpret the input.
• Common attack patterns include inserting newline characters to disrupt log files, command sequences, or data processing workflows.

• Security Impact:

• Direct consequences of successful exploitation include altered data processing, unauthorized command execution, or corrupted log files.
• Potential cascading effects may involve denial of service, data leakage, or privilege escalation.
• Business impact could include operational disruption, data integrity issues, and reputational damage.

• Prevention Guidelines:

• Specific code-level fixes include validating and sanitizing input to ensure that line delimiters are properly neutralized before data is processed.
• Security best practices involve implementing input validation routines that specifically check for and handle line delimiter characters.
• Recommended tools and frameworks include using libraries that handle data parsing safely and incorporating security-focused static analysis tools to identify vulnerabilities during development.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

function logUserInput(userInput) {
    /*
    This function logs user input to the console. However, it does not neutralize
    line delimiters, allowing an attacker to insert additional log entries.
    */
    console.log(`User Input: \${userInput}`);  // Vulnerability: Input is directly logged without sanitization
}

How to fix Improper Neutralization of Line Delimiters?

To mitigate this vulnerability in JavaScript, we should sanitize the input by replacing newline characters with a safe alternative. This prevents attackers from exploiting line delimiters to manipulate log entries. String replacement methods can be used to achieve this sanitization.

Fixed Code Example

function logUserInput(userInput) {
    /*
    This function logs user input to the console. It neutralizes line delimiters
    by replacing newline characters with a safe representation, preventing log injection.
    */
    const sanitizedInput = userInput.replace(/\n/g, "\\n").replace(/\r/g, "\\r");  // Sanitize input to neutralize line delimiters
    console.log(`User Input: \${sanitizedInput}`);  // Safely log sanitized input
}

In this JavaScript example, improper neutralization of line delimiters could lead to log injection attacks. By replacing newline characters with safe alternatives, we prevent attackers from manipulating log entries, ensuring that the logging mechanism remains reliable and secure.