What is Improper Handling of Insufficient (CWE-333)?

TL;DR: Improper Handling of Insufficient Entropy in TRNG (CWE-333) occurs when a program runs out of random numbers due to insufficient entropy, leading to DoS: Crash, Exit, or Restart.

At-a-Glance

What is Improper Handling of Insufficient Entropy in TRNG?

Improper Handling of Insufficient Entropy in TRNG (CWE-333) is a type of vulnerability that occurs when a program runs out of random numbers due to insufficient entropy. As defined by the MITRE Corporation under CWE-333, and classified by the OWASP Foundation under None…

Quick Summary

Improper Handling of Insufficient Entropy in TRNG can lead to DoS: Crash, Exit, or Restart and is typically exploitable with Low likelihood. Waiting for more random numbers to be created is the primary mitigation strategy.

Jump to: What is Improper Handling of Insufficient Entropy in TRNG? · Quick Summary · Improper Handling of Insufficient Entropy in TRNG Overview · How Improper Handling of Insufficient Entropy in TRNG Works · Business Impact of Improper Handling of Insufficient Entropy in TRNG · Improper Handling of Insufficient Entropy in TRNG Attack Scenario · How to Detect Improper Handling of Insufficient Entropy in TRNG · How to Fix Improper Handling of Insufficient Entropy in TRNG · Framework-Specific Fixes for Improper Handling of Insufficient Entropy in TRNG · How to Ask AI to Check Your Code for Improper Handling of Insufficient Entropy in TRNG · Improper Handling of Insufficient Entropy in TRNG Best Practices Checklist · Improper Handling of Insufficient Entropy in TRNG FAQ · Vulnerabilities Related to Improper Handling of Insufficient Entropy in TRNG · References · Scan Your Own Site

Improper Handling of Insufficient Entropy in TRNG Overview

What: Improper Handling of Insufficient Entropy in TRNG is a type of vulnerability that occurs when a program runs out of random numbers due to insufficient entropy.

Why it matters: This can lead to DoS: Crash, Exit, or Restart and is typically exploitable with Low likelihood.

Where it occurs: Improper Handling of Insufficient Entropy in TRNG can occur in any system that relies on true random number generators (TRNG).

Who is affected: Any program that uses TRNG may be affected by this vulnerability.

Who is NOT affected: Systems that do not use TRNG or have sufficient entropy are not affected.

How Improper Handling of Insufficient Entropy in TRNG Works

Root Cause

Improper Handling of Insufficient Entropy in TRNG occurs when a program runs out of random numbers due to insufficient entropy.

Attack Flow

1. The attacker attempts to exploit the vulnerability by running the program until it runs out of random numbers.
2. The program crashes or blocks, resulting in DoS: Crash, Exit, or Restart.

Prerequisites to Exploit

• The program must use TRNG.
• The program must run out of random numbers due to insufficient entropy.

Vulnerable Code

import java.security.SecureRandom;

public class Example {
    public static void main(String[] args) {
        SecureRandom secureRandom = new SecureRandom();
        byte[] bytes = new byte[1024];
        secureRandom.nextBytes(bytes);
        // ...
    }
}

The vulnerable code uses SecureRandom to generate random numbers, but does not check if the entropy pool is sufficient.

Secure Code

import java.security.SecureRandom;

public class Example {
    public static void main(String[] args) {
        SecureRandom secureRandom = new SecureRandom();
        byte[] bytes = new byte[1024];
        // Check if the entropy pool is sufficient before generating random numbers.
        if (secureRandom.entropyAvailable() < 128) {
            throw new Exception("Insufficient entropy available.");
        }
        secureRandom.nextBytes(bytes);
        // ...
    }
}

The secure code checks if the entropy pool is sufficient before generating random numbers.

Business Impact of Improper Handling of Insufficient Entropy in TRNG

Confidentiality: None.

Integrity: None.

Availability: DoS: Crash, Exit, or Restart.

• Financial impact: The program may crash or block, resulting in downtime and lost productivity.
• Compliance impact: The vulnerability may lead to non-compliance with security regulations.
• Reputation impact: The vulnerability may damage the reputation of the organization.

Improper Handling of Insufficient Entropy in TRNG Attack Scenario

1. The attacker attempts to exploit the vulnerability by running the program until it runs out of random numbers.
2. The program crashes or blocks, resulting in DoS: Crash, Exit, or Restart.

How to Detect Improper Handling of Insufficient Entropy in TRNG

Manual Testing

• Run the program and observe if it crashes or blocks when generating random numbers.
• Check the entropy pool size using SecureRandom.entropyAvailable().

Automated Scanners (SAST/DAST)

• Use automated scanners to detect if the program uses TRNG and generates random numbers without checking the entropy pool size.

PenScan Detection

PenScan’s scanner engines actively test for this issue.

False Positive Guidance

• Be cautious when detecting this vulnerability, as it may be triggered by legitimate use of TRNG.
• Verify that the program is indeed running out of random numbers due to insufficient entropy before reporting a finding.

How to Fix Improper Handling of Insufficient Entropy in TRNG

• Waiting for more random numbers to be created is the primary mitigation strategy.

Framework-Specific Fixes for Improper Handling of Insufficient Entropy in TRNG

Java

import java.security.SecureRandom;

public class Example {
    public static void main(String[] args) {
        SecureRandom secureRandom = new SecureRandom();
        byte[] bytes = new byte[1024];
        // Check if the entropy pool is sufficient before generating random numbers.
        if (secureRandom.entropyAvailable() < 128) {
            throw new Exception("Insufficient entropy available.");
        }
        secureRandom.nextBytes(bytes);
        // ...
    }
}

Node.js

const crypto = require('crypto');

function generateRandomNumber() {
    const randomBytes = crypto.randomBytes(1024);
    // Check if the entropy pool is sufficient before generating random numbers.
    if (randomBytes.length < 128) {
        throw new Error("Insufficient entropy available.");
    }
    return randomBytes;
}

Python/Django

import os

def generate_random_number():
    # Check if the entropy pool is sufficient before generating random numbers.
    if os.urandom(1024).length < 128:
        raise Exception("Insufficient entropy available.")
    return os.urandom(1024)

How to Ask AI to Check Your Code for Improper Handling of Insufficient Entropy in TRNG

Review the following [language] code block for potential CWE-333 Improper Handling of Insufficient Entropy in TRNG vulnerabilities and rewrite it using a primary fix technique.

import java.security.SecureRandom;

public class Example {
    public static void main(String[] args) {
        SecureRandom secureRandom = new SecureRandom();
        byte[] bytes = new byte[1024];
        // Check if the entropy pool is sufficient before generating random numbers.
        if (secureRandom.entropyAvailable() < 128) {
            throw new Exception("Insufficient entropy available.");
        }
        secureRandom.nextBytes(bytes);
        // ...
    }
}

Improper Handling of Insufficient Entropy in TRNG Best Practices Checklist

✅ Verify that the program uses TRNG and generates random numbers without checking the entropy pool size. ✅ Check the entropy pool size using SecureRandom.entropyAvailable() before generating random numbers.

Improper Handling of Insufficient Entropy in TRNG FAQ

How does Improper Handling of Insufficient Entropy in TRNG occur?

Improper Handling of Insufficient Entropy in TRNG occurs when a program runs out of random numbers due to insufficient entropy.

What are the consequences of Improper Handling of Insufficient Entropy in TRNG?

The consequences of Improper Handling of Insufficient Entropy in TRNG include DoS: Crash, Exit, or Restart.

How can I detect Improper Handling of Insufficient Entropy in TRNG?

You can detect Improper Handling of Insufficient Entropy in TRNG through manual testing and automated scanners (SAST/DAST).

How can I fix Improper Handling of Insufficient Entropy in TRNG?

You can fix Improper Handling of Insufficient Entropy in TRNG by waiting for more random numbers to be created.

What are the best practices for preventing Improper Handling of Insufficient Entropy in TRNG?

The best practices for preventing Improper Handling of Insufficient Entropy in TRNG include verifying return values and testing your code.

How can I use AI to check my code for Improper Handling of Insufficient Entropy in TRNG?

You can use AI to check your code for Improper Handling of Insufficient Entropy in TRNG by reviewing the following [language] code block for potential CWE-333 Improper Handling of Insufficient Entropy in TRNG vulnerabilities and rewriting it using a primary fix technique.

What are some common mistakes when preventing Improper Handling of Insufficient Entropy in TRNG?

Some common mistakes when preventing Improper Handling of Insufficient Entropy in TRNG include not verifying return values and not testing your code.

Vulnerabilities Related to Improper Handling of Insufficient Entropy in TRNG

References

• MITRE CWE-333
• NVD

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Improper Handling of Insufficient Entropy in TRNG and other risks before an attacker does.