CWE-201

Introduction

CWE-201: Information Exposure Through Sent Data refers to a vulnerability where an application inadvertently leaks sensitive data through its outbound network traffic. When the sensitive data consists of Personally Identifiable Information (PII), the risks escalate significantly. This article delves into the specific risks associated with PII exposure through CWE-201 and provides practical remediation techniques to secure PII data in applications developed in Java, JavaScript, and Python.

Understanding the Risks

Direct Risks

• Identity Theft: Exposure of PII such as Social Security numbers, birthdates, or credit card information can lead directly to identity theft.
• Financial Loss: Compromised bank details or payment card information can result in direct financial theft.
• Access to Additional Accounts: Leaked information like email addresses and passwords can be used to gain access to other personal and business accounts.

Indirect Risks

• Reputation Damage: Incidents of PII exposure can harm the reputation of the involved organization, leading to lost trust and customer churn.
• Legal and Regulatory Penalties: Non-compliance with data protection regulations such as GDPR, HIPAA, or CCPA can result in hefty fines and legal actions.
• Operational Disruption: Dealing with the aftermath of a data breach often requires significant resources, diverting focus from normal business operations.

Remediation Techniques

Effective remediation of CWE-201 when PII is involved includes several strategies such as omitting sensitive data where unnecessary, masking data to prevent real values from being exposed, and encrypting data to protect its confidentiality during transmission.

Omitting Data

public class UserInfo {

    private String name;

    private String address; // PII not required in the output

​

    public UserInfo(String name, String address) {

        this.name = name;

        this.address = address;

    }

​

    public String getName() {

        return name;

    }

​

    // No getAddress method to prevent exposure

}

Masking Data

public class User {

    public String maskEmail(String email) {

        String[] parts = email.split("@");

        String maskedLocal = parts[0].replaceAll("(?<=.{2}).", "*");

        return maskedLocal + "@" + parts[1];

    }

}

Encrypting Data

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import javax.crypto.spec.SecretKeySpec;

​

public class EncryptionUtil {

    public static String encryptData(String data) throws Exception {

        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");

        keyGenerator.init(128);

        SecretKey secretKey = keyGenerator.generateKey();

        Cipher cipher = Cipher.getInstance("AES");

        cipher.init(Cipher.ENCRYPT_MODE, secretKey);

        byte[] encrypted = cipher.doFinal(data.getBytes());

        return Base64.getEncoder().encodeToString(encrypted);

    }

}

Conclusion

Implementing these remediation strategies will significantly reduce the risk of PII exposure through CWE-201 vulnerabilities. Developers should assess their applications for potential data exposure points and apply the appropriate methods to protect sensitive information.