Brute Force Attacks: Difficulty & Prevention

TL;DR

Brute force attacks try every possible combination of characters to guess a password or key. How long it takes depends on the length and complexity of what they’re trying to crack. Strong, unique passwords and multi-factor authentication are your best defenses.

Understanding Brute Force Attacks

A brute force attack is essentially trial and error. Attackers use software to systematically try every possible password or key until the correct one is found. The longer and more complex the target, the harder (and slower) it becomes.

How Difficult Is Brute Forcing?

1. Password Length: This is the biggest factor. Each extra character dramatically increases the number of possibilities.
   • 8 characters: Around 4 billion combinations (relatively easy to crack with modern hardware).
   • 12 characters: Around 1.6 trillion combinations (takes considerably longer, but still possible).
   • 16 characters: Around 18 quadrillion combinations (very difficult without significant resources).
2. Character Set: Using more character types (lowercase, uppercase, numbers, symbols) increases complexity.
   • Lowercase only: Fastest to crack.
   • Lowercase + Uppercase: Slower than lowercase only.
   • Lowercase + Uppercase + Numbers: Even slower.
   • Lowercase + Uppercase + Numbers + Symbols: Slowest, most secure (if long enough).
3. Hashing Algorithms: Passwords aren’t stored in plain text; they’re converted into a hash. Stronger hashing algorithms (like bcrypt or Argon2) are designed to be slow, making brute force attacks more time-consuming.
4. Hardware: Attackers can use powerful computers and even cloud resources to speed up the process. GPUs are particularly effective for cracking passwords.
5. Rate Limiting & Account Lockout: Many systems limit the number of failed login attempts within a certain timeframe, making brute force attacks less practical.

Estimating Brute Force Time

It’s hard to give exact times, but here’s an idea. Let’s say you have a password with 8 characters using lowercase letters and numbers (62 possible characters). A computer can try roughly 10 billion passwords per second.

# Example calculation (very simplified)

Total combinations = 62^8  (approximately 218 trillion)

Time to crack = Total combinations / Passwords per second

Time to crack ≈ 21,800 seconds (around 6 hours) - this is a rough estimate!

How to Protect Yourself

1. Use Strong, Unique Passwords: At least 12 characters, and use a mix of lowercase, uppercase, numbers, and symbols.
2. Password Manager: Use a password manager to generate and store strong passwords for each account.
3. Multi-Factor Authentication (MFA): This adds an extra layer of security by requiring a code from your phone or another device in addition to your password. This makes brute force attacks much harder, even if the password is compromised.
4. Enable Account Lockout: Configure systems to lock accounts after several failed login attempts.
5. Rate Limiting: Limit the number of login attempts allowed per IP address or user account within a specific timeframe.
6. Regularly Update Software: Keep your operating system and software up-to-date with the latest security patches.
7. Monitor for Suspicious Activity: Keep an eye on your accounts for any unusual login attempts or changes to your settings.

Tools Attackers Use

Attackers use tools like:

• Hydra: A popular parallelized brute force tool that supports many protocols.
• John the Ripper: A password cracking tool with various modes and features.
• Hashcat: Another powerful password cracking tool, often used with GPUs.