Brute Force vs. Dictionary Attack: What’s the Difference?

Last updated on February 26, 2025

The main difference between a brute force attack and a dictionary attack is that in a brute force attack, a hacker tries to crack a password using every possible combination of characters, whereas, in a dictionary attack, the hacker tries a list of known or commonly used passwords. While a brute-force attack tries every character combination to break a password, a dictionary attack only attempts passwords previously leaked or commonly used by others.

Dictionary vs. Brute Force Attacks: Key Takeaways

• Different Attack Methods: Brute force attacks systematically try every possible password combination, while dictionary attacks use precompiled lists of likely passwords.
• Impact of Password Complexity: The effectiveness of both attack types hinges on password strength, making robust password policies based on NIST Password Guidelines essential.
• Mitigation through Multi-Factor Authentication: Implementing MFA, such as with Rublon MFA, significantly enhances security by adding an extra verification layer beyond just the password.
• Proactive Account Protection: Enforcing account lockout policies can help detect and deter malicious attempts. For instance, you can block users after consecutive failed authentications to minimize the risk of unauthorized access.
• Layered Security Approach: Combining strong passwords, MFA, and proactive lockout strategies creates a multi-layered defense, reducing the overall vulnerability to brute force and dictionary attacks.

What is Brute Force Attack?

A brute force attack is a method of breaking into a password-protected account or system by trying every possible combination of characters. A brute force attack is a type of cyberattack where the attacker uses an automated system to guess the correct combination of username and password to gain access to a system or website. This type of attack is often used to gain access to websites, accounts, or other secure systems. By repeatedly trying different combinations of usernames and passwords, the attacker can eventually guess the correct combination, allowing them to gain access to the system. It’s important for businesses to keep their security measures up-to-date in order to protect against brute force attacks.

How Does Brute Force Attack Work?

In a brute force attack, the hacker will use sophisticated software to systematically try thousands or even millions of combinations of characters until the correct password is discovered. If a hacker is successful in performing a brute force attack, they can gain access to a system and any data it contains.

Here’s how a brute force attack works:

1. A hacker first identifies a target system. This can be a website, network, admin account, user account, or another system protected with a password.
2. To start the attack, the hacker uses a bot that enters password guesses into a form field on the target system.
3. The bot waits for a response from the website after each guess to determine if the guess was correct or not.
4. If the bot is successful in guessing the password, the hacker can gain access to the system and any data it contains.
5. If the bot is not successful in guessing the password, the hacker can use more powerful methods known as dictionary attacks, rainbow tables, hybrid attacks, and so on.

Brute Force Attack Example

If your password is ‘banana’, the bot running the brute force attack will keep trying every possible combination of characters until it arrives at the correct combination. This can be a time-consuming and inefficient process when it comes to longer passwords. But a password as short as ‘banana’ should not take much time to crack. So, the best way to protect yourself from brute force attacks is to focus on the length of the password rather than its complexity. The longer the password, the harder it is to crack.

Key Takeaway: Longer passwords provide greater protection against brute force attacks.

What is Dictionary Attack?

A Dictionary Attack is a type of cyberattack wherein a malicious actor uses a list of words and phrases to gain access to a system. A Dictionary Attack uses a targeted sequence of words or phrases to try to gain access to a secure system. It is used to gain unauthorized access to a user account or to decrypt sensitive data. The attack works by exploiting the fact that many people use common words or phrases as passwords or use variations of the same password. Dictionary Attacks are typically used in combination with other types of attacks, such as brute force or rainbow table attacks, to make them more successful.

How Does Dictionary Attack Work?

In a dictionary attack, the hacker will use a dictionary file to systematically try thousands or even millions of commonly used passwords listed in that file until the correct password is discovered. If a hacker is successful in performing a dictionary attack, they can gain access to a system and any data it contains.

Here’s how a dictionary attack works:

1. The attacker creates or finds a list of common passwords or words and includes them in a dictionary file. Such files can easily be found online.
2. To start the attack, the hacker uses a bot that enters password guesses into a form field on the target system.
3. The bot waits for a response from the website after each guess to determine if the guess was correct or not.
4. If the password guess is incorrect, the bot will move on to the next password in the dictionary file.
5. The bot continues this process until a correct password guess is found.
6. Once the bot finds the correct username and password combination, the hacker can gain access to the website and its data.

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Dictionary Attack Example

If your password is ‘banana’, chances are that:

1. This is a popular password other people use.
2. This password was used by a person whose login credentials leaked during a data breach.

If the password is ‘banana’, the hacker may assume it is on a list of commonly used passwords and launch a dictionary attack, which is basically a list of all the possible passwords they will try. This means that instead of using every possible combination, the hacker is using a list of common passwords during the attack. Such common passwords include ‘123456’, ‘qwerty’, and ‘password’, among millions of others. Therefore, if your password is ‘banana’, it is highly likely that it is included in the list of common passwords hackers use during dictionary attacks, and as such, you should consider changing it.

Key Takeaway: Constructing a unique password nobody else is likely to use makes it harder to crack it.

What’s the Difference Between Brute Force and Dictionary Attack?

Differences Overview: Brute Force vs. Dictionary Attacks

A brute force attack tries all possible combinations of characters until one combination works, while a dictionary attack narrows the combinations to a list of common or known passwords. This list may include popular passwords used by many people as well as leaked credentials. The passwords are typically ordered by popularity, meaning the most common ones are checked first. As a result, a dictionary attack is generally less time-consuming than a full brute-force attack, but it is also less effective against unique, unleaked passwords.

Advanced Brute Force Techniques

It is important to note that when we refer to a brute force attack, we mean a simple version that attempts every possible combination until success is achieved. However, advanced brute force attacks can be more efficient by taking into account specific password rules—such as requiring at least one uppercase letter or number—thus excluding many irrelevant combinations. Even with these optimizations, these attacks still try every valid combination based on the set rules.

Revisiting Dictionary Attacks

A dictionary attack is essentially a specialized form of brute force that limits its attempts to a pre-compiled list of common or known passwords. This list, which includes both popular choices and previously leaked passwords, is arranged in order of popularity so that the most frequently used passwords are attempted first. Consequently, while a dictionary attack tends to be faster than a full brute-force approach, it remains less effective when faced with unique or non-leaked passwords.

Key Takeaway: A brute force attack tries all possible character combinations to crack a password. In contrast, a dictionary attack tries only the passwords previously leaked or commonly used by others.

Brute Force Attack vs. Dictionary Attack: Difference Table

Brute Force Attack	Dictionary Attack
Attempts to guess a password by systematically trying out every possible combination of characters	Attempts to guess a password by systematically trying out every possible word in a dictionary
Slow and computationally intensive	Fast but limited by the words in the dictionary
Can guess passwords of any length	Usually limited to passwords of a reasonable length

Hybrid Attacks

Modern password-cracking tools use hybrid attack modes that combine brute force and dictionary attacks (and some other techniques) to achieve the highest possible hacking efficiency. Some users make the mistake of appending a different substring of characters to their password instead of changing the password altogether. For example, a user whose password was ‘pancakes’ changes it to ‘pancakes1’. A hacker can use a hybrid attack to hack this password. While ‘pancakes’ is from the word list used during a dictionary attack, the number ‘1’ is appended in a way that brute-force attacks work.

Enable MFA to Mitigate Brute Force and Dictionary Attacks

Use a long unique password to increase the security of your account. Still, a scenario in which hackers leak passwords, including your password, is possible. In this case, the safety of your account is jeopardized regardless of the length and complexity of your password. Multi-Factor Authentication (MFA) is a solution to that. MFA adds an additional authentication step and requires completing all authentication steps before granting access. A person who knows the password but fails to accomplish the second step cannot access the account. As a result, enabling MFA on all user accounts considerably decreases the likelihood of a successful cyberattack. This is a massive advantage because MFA can prevent 99.9% of attacks on your accounts.

Key Takeaway: Secure your account with a long and unique password and Multi-Factor Authentication (MFA) to mitigate brute force and dictionary attacks. MFA requires completing all authentication steps before granting access and can decrease the likelihood of a successful cyberattack by 99.9%. Enable MFA on all accounts for maximum security.

Strengthening Security With Proactive Account Lockout

While understanding the technical differences between brute force and dictionary attacks is essential, equally important is implementing robust mitigation strategies. One such strategy is establishing a proactive account lockout mechanism that can block users after consecutive failed authentications. This approach limits the window of opportunity for automated attacks. It also signals potential malicious activity to administrators.

Key Benefits of Account Lockout Policies

• Early Detection of Malicious Attempts: By monitoring failed login attempts, organizations can quickly identify abnormal patterns that may indicate a brute force or dictionary attack.
• Limiting Attack Vectors: Locking out accounts after a set number of failed attempts restricts an attacker’s ability to continuously guess passwords, thereby reducing the overall risk.
• Compliance with Best Practices: Implementing an account lockout mechanism aligns with industry best practices for secure authentication, bolstering both compliance and user trust.
• Layered Security: When combined with Multi-Factor Authentication (MFA), proactive lockouts add another layer of defense, ensuring that even if a password is compromised, the account remains protected.

Considerations for Implementation

• Threshold Settings: Determine a balanced threshold that effectively deters attackers without causing undue inconvenience for legitimate users.
• Notification and Recovery: Ensure that users receive clear notifications when their account is locked and provide a secure recovery process to restore access.
• Continuous Monitoring: Regularly review account lockout logs and adjust policies as needed based on emerging threat patterns and user behavior.

Integrating such a proactive lockout mechanism with existing security measures allows organizations to build a more resilient defense against both brute force and dictionary attacks—ensuring that every login attempt is scrutinized and secured.

Expanding the Discussion: Understanding Credential Stuffing

While this article thoroughly examines brute force and dictionary attacks, one critical threat remains under-discussed: credential stuffing. Credential stuffing is a form of brute force attack that leverages the vast amounts of compromised username and password pairs from previous breaches. Attackers use these credentials across multiple platforms, banking on the common user behavior of password reuse. Unlike overt brute force attacks, credential stuffing often flies under the radar, as it uses valid credentials, which makes detection more challenging. The best prevention strategy against credentials stuffing is enabling organization-wide multi-factor authentication (MFA).

Don’t Be At the Mercy of Passwords, Enable Rublon MFA

Both brute-force attacks and dictionary attacks aim to break passwords. Hackers compromise passwords with the hope of gaining unauthorized access to user accounts. You can get the better of hackers by adding an additional layer of security to your account. Multi-Factor Authentication does just that and much more.

Do not want hackers to break into your account? Start a Free 30-Day Rublon MFA Trial: