CWE-143: Improper Neutralization of Record Delimiters

What is Improper Neutralization of Record Delimiters?

• Overview: CWE-143, Improper Neutralization of Record Delimiters, occurs when a software system fails to properly handle special characters that separate records in data streams. This can lead to incorrect parsing and unintended actions when data is processed.

• Exploitation Methods:

• Attackers can exploit this vulnerability by injecting unexpected record delimiters into data inputs, leading to data being misinterpreted or corrupted.
• Common attack patterns include inserting additional delimiters to break data into more records than intended or altering delimiter positions to change data interpretation.

• Security Impact:

• Direct consequences include data corruption, unauthorized data access, or denial of service due to incorrect data processing.
• Potential cascading effects may involve the triggering of logic errors, unauthorized information disclosure, or system crashes.
• Business impact may include data integrity loss, reputational damage, and legal liabilities due to data mishandling.

• Prevention Guidelines:

• Specific code-level fixes involve validating and sanitizing inputs to ensure delimiters are correctly handled and neutralized before processing.
• Security best practices include implementing input validation and output encoding, and employing strict boundary checks.
• Recommended tools and frameworks involve using libraries that provide secure handling of data streams and record parsing to mitigate delimiter-related issues.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

```javascript dataProcessor.js {10-12}
// This code processes CSV data from user input. It directly uses input data
// without neutralizing record delimiters, which could lead to injection
// vulnerabilities if the input contains unexpected delimiters like newlines.

function parseCSV(input) {
    const records = input.split("\n"); // Splits input by newline, vulnerable to delimiter injection
    const data = records.map(record => record.split(",")); // Further splits by comma
    return data;
}

const userInput = "name,age\nJohn Doe,30\nJane,25"; // Potentially malicious input
console.log(parseCSV(userInput));

Explanation

In the vulnerable code example, the parseCSV function naively splits the input string by newlines (\n) to separate records. This approach does not account for potential misuse where an attacker could inject additional newline characters to manipulate the data parsing process. This can lead to injection vulnerabilities if the input is not properly sanitized.

How to fix Improper Neutralization of Record Delimiters?

To fix this issue, we should sanitize or escape any input received from potentially untrusted sources. Using a well-established CSV parsing library can automatically handle special characters and neutralize record delimiters safely. Libraries like csv-parse in Node.js are designed to handle various edge cases and prevent delimiter injection by default.

Fixed Code Example

// This code demonstrates the fixed implementation using a CSV parsing library,
// which inherently handles special characters and neutralizes record delimiters safely.

const parse = require('csv-parse/lib/sync');

function parseCSV(input) {
    try {
        // Using a CSV parsing library to safely handle input
        const records = parse(input, {
            columns: true, // Parses the first row as column headers
            skip_empty_lines: true, // Ignores empty lines
        });
        return records;
    } catch (err) {
        console.error("Error parsing CSV:", err);
        return [];
    }
}

const userInput = "name,age\nJohn Doe,30\nJane,25"; // Safely handled
console.log(parseCSV(userInput));

Explanation

In the fixed example, the csv-parse library is used to handle CSV parsing. This library provides a robust solution by automatically managing newlines and other potentially dangerous characters. Using such a library helps avoid manual parsing errors and mitigates the risk of injection vulnerabilities. The library's options, such as columns and skip_empty_lines, ensure that the parsing process is both safe and efficient. This demonstrates best practices for handling CSV data securely in JavaScript.