Brute Force Attack

A brute force attack represents a cyberattack in which attackers systematically attempt every possible combination of usernames and passwords until they successfully gain access to an account. The term "brute force" conveys the concept of using sheer computational power and persistence to break through security measures.

This blog explores the critical issue of brute force attacks, outlining their mechanics and potential impact on security. It also provides essential strategies for security engineers to fortify defenses against these persistent threats.

What is a Brute Force Attack?

A brute force attack is a method hackers use to gain access to accounts or systems by systematically trying every possible combination of passwords or keys until finding the correct one. This approach resembles attempting to open a lock by testing every key. Hackers often target weak or common passwords, which increases their chances of success. Although brute force attacks can be effective, they are also time-consuming. Security measures like strong, complex passwords and multi-factor authentication can mitigate these attacks.

Types of Brute Force Attacks

Brute force attacks come in various forms, each with its own characteristics and methods. Understanding these different types is crucial for developing effective defense strategies. Let's explore the main types of brute force attacks:

1. Basic Brute Force Attacks

This simplest form of attack involves hackers trying every possible password combination until successful. For example, if a password is "1234," the attacker will attempt "0000", "0001", and so on until reaching "1234" this method proves effective on simple, short passwords but becomes impractical for longer, more complex ones.

Consider an attacker targeting an online voting system where users must enter a 6-digit PIN to cast their vote. The attacker writes a script that automatically tries every possible PIN combination, starting from "000000" and continuing through "999999" by systematically testing each combination, the attacker eventually finds the correct PIN for one or more accounts and uses these PINs to cast fraudulent votes.

def cast_vote(user_id, pin):
    # Check if the provided PIN matches the user's stored PIN
    if verify_pin(user_id, pin):
        # Allow the user to cast their vote
        record_vote(user_id)
        return "Vote cast successfully"
    else:
        return "Invalid PIN"

def verify_pin(user_id, pin):
    # Simulate fetching the stored PIN for the user
    stored_pin = fetch_stored_pin(user_id)
    return stored_pin == pin

# Example usage
user_id = "user123"
pin = input("Enter your 6-digit PIN: ")
print(cast_vote(user_id, pin))

The code does not limit the number of PIN entry attempts, allowing an attacker to write a script that systematically tries every possible 6-digit PIN combination (from "000000" to "999999") until discovering the correct one.

2. Dictionary-Based Attacks

A simple brute force attack represents one of the most fundamental techniques employed by cybercriminals to gain unauthorized access to systems. This method relies on automation to systematically guess passwords or encryption keys by trying every possible combination until the correct one is found. Below is a detailed exploration of how simple brute force attacks operate, their effectiveness, and the challenges they encounter.

How Simple Brute Force Attacks Work

1. Automation and Tools

Attackers utilize automated software tools and scripts that can generate and test numerous password combinations at high speeds. These tools can make hundreds to thousands of guesses per second, significantly accelerating the process compared to manual attempts. Automation allows attackers to scale their efforts efficiently.

1. Trial-and-Error Approach

The core of a simple brute force attack follows a trial-and-error methodology:

• Attackers select a target system, such as a website, server, or application.

• The software begins attempting various combinations of usernames and passwords until successfully logging in.

Example

Consider an example where an attacker targets a user account with the username "Manager":

In this scenario, the attacker tries multiple combinations until finding the correct password, "BBBB123". The effectiveness of a brute force attack largely depends on the computational power available to the attacker. Modern attackers may use botnets—networks of compromised computers—to increase their guessing speed. Researchers have demonstrated that with sufficient resources, it is possible to guess up to 350 billion passwords per second.

3. Hybrid Attacks

Hybrid attacks represent a sophisticated form of cyberattack that combines multiple techniques to exploit vulnerabilities in systems, particularly focusing on password cracking. This approach enhances the attacker's chances of success by leveraging the strengths of different methods, making it more challenging for security measures to defend against these threats.

How Hybrid Attacks Work

1. Combination of Techniques

Hybrid attacks typically merge two or more attack methods, with the most common combination being dictionary and brute force attacks.

Attackers utilize a dictionary attack by attempting known credentials from a predefined list of commonly breached passwords or phrases. They then apply brute force techniques to generate variations of these known passwords. Attackers add numbers and symbols or change letter cases to create potential matches based on user habits.

Example of a Hybrid Attack

For example, an attacker targets an e-commerce website where users create accounts with passwords. The attacker begins by using a dictionary of common passwords, such as "password." To increase the chances of success, they modify these passwords by adding numbers or special characters.

The attacker tries variations like password1, password123, or password!. This hybrid approach combines the efficiency of dictionary attacks with the thoroughness of brute force, enabling the attacker to crack passwords that users often create by slightly modifying common phrases.

def create_account(username, password):
    # Store the username and password in the database
    store_user_credentials(username, password)
    return "Account created successfully"

def login(username, password):
    # Retrieve the stored password for the username
    stored_password = fetch_stored_password(username)

    # Check if the provided password matches the stored password
    if stored_password == password:
        return "Login successful"
    else:
        return "Invalid username or password"

# Example usage
username = input("Enter username: ")
password = input("Enter password: ")
create_account(username, password)

The vulnerability lies in weak password storage, as this code fails to hash passwords before storing them, leaving them exposed if the database is compromised. Additionally, the code does not enforce password complexity, allowing users to create simple, easily guessable passwords like password or password123.

Furthermore, the absence of rate limiting in the login function enables attackers to perform brute force or hybrid attacks by repeatedly attempting common passwords and their variations without restrictions on the number of attempts.

4. Reverse Brute Force Attacks

Reverse brute force attacks serve as a targeted approach in cybersecurity that flips the traditional brute force method on its head. Instead of guessing passwords for a specific username, attackers start with a known password and attempt to find matching usernames across multiple accounts. This method proves particularly effective against systems with weak password policies or where users frequently reuse passwords.

How Reverse Brute Force Attacks Work

Attackers often begin reverse brute force attacks by acquiring known passwords from data breaches, leaked databases, or lists of commonly used passwords such as "password123". They then target multiple usernames by systematically testing the known password against a list of potential usernames. This list typically includes common usernames, email addresses, or any publicly available usernames.

Example

Instead of starting with a list of possible passwords, attackers begin with a known password and attempt to match it with multiple usernames or accounts. For instance, if password123 is known to be used by many people, the attacker will test it against different usernames on a system.

An attacker might target a company’s internal network, knowing that password123 is a commonly used password. Instead of trying different passwords for a specific username, the attacker uses password123 and tests it across a list of usernames, such as jdoe, asmith, and mjones. This exploits the tendency of many users to select weak, common passwords, allowing the attacker to gain access to any account where password123 is the password.

def login(username, password):
    # Fetch the stored password for the username
    stored_password = fetch_stored_password(username)

    # Check if the provided password matches the stored password
    if stored_password == password:
        return "Login successful"
    else:
        return "Invalid username or password"

# Example usage
password_to_test = "password123"
usernames = ["jdoe", "asmith", "mjones"]

for username in usernames:
    if login(username, password_to_test) == "Login successful":
        print(f"Access granted for user {username} with password {password_to_test}")

The vulnerability arises from the system allowing the use of weak, common passwords like password123, making it easy for attackers to guess credentials. Additionally, the absence of an account lockout mechanism after multiple failed login attempts leaves the system exposed to brute force attacks, enabling attackers to test the same password across multiple usernames without restrictions.

How Brute Force Attack Work?

Brute force attacks represent a fundamental yet effective method for cybercriminals to gain unauthorized access to systems by systematically guessing passwords or encryption keys. This exploration details the mechanics associated with brute force attacks.

Basic Mechanism

A brute force attack attempts every possible combination of characters, numbers, and symbols until the correct login credentials are discovered. Attackers deploy automated software or scripts that rapidly input these combinations into the target system's login interface. The process involves:

1. Automated Tools: Attackers leverage software that generates and tests thousands of combinations per second, significantly speeding up the guessing process compared to manual attempts. These tools enable attackers to efficiently attempt numerous username and password combinations, increasing their chances of success within a shorter time frame. As a result, security measures must adapt to counteract the effectiveness of these automated attacks.

2. Trial-and-Error: Brute force attacks depend on sheer computational power, employing trial-and-error methods instead of sophisticated techniques to crack passwords. This approach relies on testing multiple combinations until the correct credentials are found, making it a straightforward yet effective strategy for attackers. Organizations must recognize this vulnerability and implement robust security measures to protect against the relentless nature of such attacks.

Target Systems

Attackers typically target web applications, focusing on login pages of websites with weak security measures. They also attack servers and databases that require authentication. Additionally, attackers attempt to decrypt data by guessing encryption keys.

Tools Used in Brute Force Attacks

Brute force attacks utilize various tools designed to automate the guessing of passwords, encryption keys, or PINs. These tools vary in sophistication, speed, and functionality, catering to different aspects of brute force attacks—from simple password cracking to more complex cryptographic key discovery. Below is a detailed overview of some commonly used tools in brute force attacks.

1. Aircrack-ng

Aircrack-ng assesses Wi-Fi network security primarily. It captures packets and analyzes wireless network security, cracking WEP and WPA/WPA2 keys using dictionary and brute force methods. The tool audits wireless security comprehensively and identifies network vulnerabilities effectively. Aircrack-ng runs on multiple operating systems, including Windows, Linux, and macOS, making it widely accessible to users.

2. John the Ripper

John the Ripper serves as a versatile open-source password recovery tool. It automatically detects password hash types and supports various attack modes, including dictionary and brute force attacks. Security engineers can customize John the Ripper to tailor their cracking efforts, making it effective for cracking complex passwords found in various systems. The tool works on many platforms, including Unix-based systems and Windows, enhancing its usability in diverse environments.

3. Hashcat

Hashcat stands out as one of the fastest password recovery utilities. It supports multiple algorithms and performs various types of attacks, including brute force, dictionary, hybrid, and mask attacks. Security engineers prefer Hashcat for its high efficiency in cracking complex hashes during penetration tests or password recovery operations. Users can access Hashcat on Windows, Linux, and macOS, making it broadly accessible.

4. THC-Hydra

THC-Hydra serves as a fast network login cracker. It supports over 50 protocols and attempts to crack multiple accounts simultaneously. Security engineers rely on THC-Hydra's effectiveness for web applications when assessing login systems' robustness against brute force attacks. THC-Hydra's compatibility with various operating systems provides flexibility for deployment in different environments.

5. Ncrack

Ncrack performs high-speed network password cracking. It executes parallelized brute force attacks to expose weak credentials that could compromise network security. Ncrack efficiently tests multiple credentials across various services, making it a valuable asset in a security engineer's toolkit. The tool operates across multiple platforms, allowing organizations to utilize it within their existing infrastructure.

6. Brutus

Brutus serves as one of the oldest and most effective brute force tools for Windows logins. It supports multi-stage authentication engines and connects to up to 60 targets simultaneously across various protocols like HTTP, FTP, and SMB. Security engineers rely on Brutus's long-standing presence in the cybersecurity field when investigating potential vulnerabilities.

Brute Force Attacks Challenges

Brute force attacks present significant challenges to cybersecurity due to their simplicity and effectiveness. Below are the challenges posed by brute force attacks.

1. Automation and Scalability

Attackers automate brute force attacks using tools capable of attempting thousands or millions of password combinations per second. This scalability enables targeting multiple accounts simultaneously, thereby increasing the chances of success.

Attackers can run automated tools continuously, often spreading attempts over extended periods to avoid detection. Additionally, the increasing power of cloud computing provides attackers with access to immense processing resources, further accelerating their ability to execute large-scale attacks and overwhelming security systems.

2. Weak Password Policies

Many users still employ weak or easily guessable passwords (e.g., "123456," "password"). This vulnerability makes brute force attacks particularly effective. The use of common passwords across multiple accounts compounds the issue, allowing attackers to exploit stolen credentials from one service on others.

Furthermore, studies indicate that a significant percentage of users opt for convenience over security, often using the same passwords across various platforms. This behavior creates a cascading effect, as a breach in one system can compromise multiple accounts, amplifying the risks associated with weak password policies.

3. Limited Detection Mechanisms

Traditional security measures may not effectively identify brute force attacks, especially if attackers utilize techniques like slow brute forcing or rotating IP addresses to blend in with legitimate traffic. Some organizations lack real-time monitoring or logging capabilities to detect unusual login patterns indicative of a brute force attack.

Additionally, attackers can leverage advanced evasion tactics, such as using proxies or VPNs, to mask their activities, making it increasingly difficult for security teams to identify and respond to ongoing attacks. This gap in detection capabilities often leaves organizations vulnerable to sustained exploitation.

4. User Behavior

Users often reuse passwords across different platforms, making it easier for attackers to gain access if they compromise just one account. A lack of user awareness regarding password security practices increases vulnerability to these attacks.

Furthermore, the psychological tendency to choose simple and memorable passwords—along with a general unawareness of the consequences of poor password hygiene—can exacerbate the situation. Security engineers face the challenge of educating users about the importance of unique and complex passwords while providing practical strategies to help them manage their credentials effectively.

Countermeasures Against Brute Force Attacks

This section highlights the importance of strong password policies, multi-factor authentication, CAPTCHA implementation, IP address restrictions, and behavioral analysis in fortifying organizational defenses.

1. Strong Password Policies

Security engineers should enforce the use of complex passwords that include a mix of uppercase letters, lowercase letters, numbers, and symbols. Encouraging longer passphrases (e.g., three random words) significantly increases security.

Additionally, implementing password expiration policies can further enhance security by forcing users to update their passwords regularly. Education programs that inform users about the risks associated with weak passwords and the benefits of strong passwords play a vital role in reinforcing these policies and creating a culture of security awareness within the organization.

2. Multi-Factor Authentication (MFA)

Implementing MFA adds an additional layer of security by requiring users to provide a second form of verification (e.g., a one-time code sent to their mobile device). This measure ensures that even if a password is compromised, unauthorized access remains prevented.

Security engineers should prioritize MFA deployment across all sensitive systems and applications, as this significantly reduces the likelihood of successful brute force attacks. Moreover, educating users about the importance of MFA helps to promote adoption and adherence, further bolstering organizational security.

3. CAPTCHA Implementation

Using CAPTCHA challenges on login pages differentiates between human users and automated bots. This effectively prevents automated scripts from executing numerous login attempts. Security engineers should consider implementing advanced CAPTCHA systems that offer a seamless user experience while maintaining strong protection against automated attacks.

Regularly updating CAPTCHA methods and monitoring their effectiveness ensures ongoing protection, as attackers continuously develop new strategies to bypass traditional CAPTCHA systems.

4. IP Address Restrictions

Implementing IP allowlisting or blocklisting restricts access to sensitive areas based on known patterns of malicious activity or trusted sources. This approach can significantly reduce the attack surface for brute force attempts.

Security engineers must continuously update these lists based on emerging threats and conduct periodic reviews to ensure that legitimate users do not face unnecessary access barriers. Combining IP restrictions with geolocation filtering further enhances security by blocking access from high-risk regions known for cybercriminal activities.

5. Behavioral Analysis

Employing machine learning-based anomaly detection systems continuously analyzes user behavior and identifies deviations from normal patterns. This enhances the ability to detect and respond to brute-force attacks in real-time.

Security engineers can refine these systems to adapt to legitimate user behavior over time, ensuring accurate identification of genuine threats. By integrating behavioral analysis with incident response protocols, organizations can effectively mitigate risks associated with brute force attacks and enhance overall security posture.

Final Thoughts

Understanding and addressing brute force attacks is crucial for maintaining the security of digital assets. Security engineers must prioritize strong password creation, implement multi-factor authentication (MFA), and utilize password managers to bolster defenses against potential breaches. Awareness of the signs of account compromise is essential, as prompt action can mitigate damage.

Integrating advanced security solutions, such as Akto, can further enhance protection by offering real-time monitoring and automated security assessments. Akto's innovative platform empowers security engineers to identify vulnerabilities and respond to threats swiftly, ensuring robust security for applications and sensitive data. By embracing these strategies and tools, organizations can create a more resilient cybersecurity posture against brute force attacks and other emerging threats.

Explore how Akto can transform security measures by visiting Akto's demo today.