Brute Force Attack

Posted on Apr 2, 2024 by

What Is a Brute Force Attack?

A brute force attack systematically unravels passwords by iterating through them one by one until the correct combination is identified. Take, for instance, a 4-digit password comprising only digits, offering a maximum of 10,000 possible combinations. In such cases, the decryption process can be completed within a maximum of 10,000 attempts. In the case of manually set passwords, which often follow a discernible pattern, attackers may employ a password dictionary like a rainbow table to expedite the cracking process by identifying frequently used passwords.

To bolster your defense against brute force attacks, consider adopting practices such as creating lengthy and intricate passwords, using unique passwords for different platforms, steering clear of personal information as password components, and regularly updating passwords. These measures significantly enhance your resilience against the potential threats posed by brute-force attacks.

Methods Used to Initiate Brute Force Attacks

Exhaustive Attack:

An exhaustive attack entails generating a comprehensive set of all potential passwords based on predetermined password length and a specified character set, and conducting an exhaustive search within this password set. Take, for instance, a 4-digit password comprising only digits, offering a maximum of 10,000 combinations, which can be deciphered within a maximum of 10,000 attempts. While theoretically applicable to any password, the time required for decryption grows exponentially as passwords become more intricate. This method finds utility in guessing randomly generated codes, such as SMS verification codes, where the probability of various randomly generated passwords remains consistent and is unaffected by human memory.

Dictionary Attack:

In a dictionary attack, commonly used passwords are compiled into a file known as a dictionary. The attacker systematically tries each password from the dictionary in an effort to unveil the actual one. This approach is typically employed to guess manually set passwords, with the likelihood of success linked to the ease of memorization.

Passwords like "12345678" and "password" are more susceptible to dictionary attacks than complex ones like "fghtsaer." While the dictionary attack boasts a slightly lower success rate, it requires less time compared to the exhaustive attack, making it a popular choice for attackers seeking a quicker compromise.

Rainbow Table Attack:

A rainbow table attack is a variant of the dictionary attack designed to efficiently compromise hash algorithms like MD5, SHA1, and SHA256/512.

To bolster security, websites refrain from directly storing user passwords in databases. Instead, each password undergoes hashing, transforming it into a sequence of nonsensical characters. As the hash algorithm is irreversible, decryption algorithms are ineffective in reverting the hashed values to the original passwords. Two approaches exist for cracking a hashed password: the exhaustive key search involves trying all possible password combinations, a time-intensive process, while the alternative involves precomputing a mapping table of all possible passwords and their corresponding hash strings, consuming substantial storage space. For instance, a 14-character alphanumeric password generates a mapping table requiring a vast storage space of 5.7 x 10(14) TB.

The rainbow table method introduces a time-space tradeoff strategy. It revolves around hashing a clear-text string to derive a hashed value, utilizing a reduction function to compute the hashed value into another clear-text string, and repeating these steps to establish a hash chain. The table only stores the initial and final strings of the hash chain, discarding intermediate strings, effectively halving the required storage space without significantly increasing computational demands. Different reduction functions, each associated with a unique color, form hash chains, creating a distinctive "rainbow effect" and earning the approach its name as a "rainbow table."

What Is a Brute Force Attack and how to defend?

When employing a rainbow table for password cracking, even a standard personal computer can achieve an astounding speed exceeding 100 billion attempts per second. To heighten security measures, it is common practice to subject a string to multiple hashing processes. For instance, MD5 may be applied iteratively, with each iteration building upon the results of the preceding MD5 operation. Additionally, a security device introduces a unique string, known as a "salt," at both the beginning and end of the original password, thereby increasing the password length before executing the hash operation. All outcomes from these variations are Syst

The most comprehensive rainbow table can successfully crack approximately 99.9% of the passwords currently in use across the Internet. This illustrates the formidable efficiency of rainbow tables in deciphering a wide range of existing password configurations.

What Is Most Vulnerable for a Brute Force Attack?

Numerous individuals opt for simplistic passwords, often relying on easily guessable information like phone numbers, dates of birth, names of relatives or pets, or reusing the same password across multiple websites, thereby rendering their accounts susceptible to easy exploitation.

By the conclusion of 2020, NordPass revealed a list of the 200 most frequently used passwords during that year. Among the notorious culprits were passwords like 123456, 123456789, "password," 12345678, 111111, 123123, 12345, 1234567890, 1234567, 000000, 1234, and others. Additionally, commonly employed passwords encompass alphanumeric combinations such as qwerty, abc123, and picture1.

Brute force attacks, while not directly causing intrusion, are frequently employed by attackers to gain access to systems and user accounts, preparing the groundwork for subsequent breaches. In individual contexts, attackers may target financial assets or identities, with the latter potentially resulting in significant financial losses. In the case of enterprises, brute force attacks are utilized to breach Telnet, POP3, and MySQL services. Successful infiltration can lead to high-risk scenarios like user information exposure, unauthorized file sharing, email leaks, or disruptions in email communication.

Methods Used to Protect Against Brute Force Attacks

Manual Enhancement: Strengthening Password Security

  • Elevate the length and intricacy of passwords.

  • A robust password should encompass digits, uppercase, and lowercase letters, along with special characters. The elongation of a password directly correlates with the time required to crack it. Once a password surpasses a certain length, brute force attacks become impractical. For instance, a server cluster with a maximum capability of 350 billion attempts per second demonstrates that cracking a 6-digit password takes only 4.08 seconds, while a 7-digit password requires 6.47 minutes, an 8-digit password 10.24 hours, a 9-digit password 40.53 days, and a 10-digit password 10.55 years.

  • Employ distinct passwords across various platforms.

  • Consistently using the same password for email, banking, and social media heightens the risk of identity theft. A strategic approach involves incorporating the abbreviation of a website name as the suffix of a password. This method ensures the adoption of unique passwords for each website, enhancing security while minimizing the likelihood of forgetfulness.

  • Refrain from utilizing dictionary words, digit-only combinations, sequences of adjacent keyboard keys, or repetitive character strings.

  • For instance, steer clear of passwords like "password," 12345678, asdfg, aaaa, or 123abc.

  • Exercise caution when selecting passwords, avoiding choices based on people's names, easily obtainable personal information (such as phone numbers or dates of birth), or the names of relatives, children, or pets. Websites often prompt users with private questions when initiating a "Forgot Password" process. Unfortunately, the answers to these questions are often readily available on our social media profiles, thereby increasing the vulnerability of our accounts to unauthorized access.

  • Foster enhanced security by regularly updating passwords. Regular changes act as an additional layer of defense against potential breaches and ensure ongoing protection for your accounts.

System Enhancement: Design Strategies for Preventing Brute Force Cracking of Passwords

To fortify a system against brute force attacks, consider incorporating the following techniques into its design:

  • Lockout Policy: Implement a lockout policy wherein a user is temporarily locked out of the system after entering an incorrect password a specified number of times. This measure helps thwart repeated, malicious attempts to crack passwords.

  • Verification Code: Introduce a verification code system, requiring users to complete simple tasks that are easily accomplished by humans but challenging for brute force tools. For instance, users may need to solve a graphic verification code puzzle or confirm their identity through an SMS message. This adds an extra layer of security to the login process.

  • Password Complexity Requirement: Enforce a password complexity policy compelling users to create long and intricate passwords, coupled with periodic password changes. This practice ensures that passwords remain resilient against brute force attacks by enhancing their complexity over time.

  • Two-Factor Authentication (2FA): Implement two-factor authentication, combining two distinct authentication factors to verify user identity. Options may include a combination of passwords, ID cards, security tokens, fingerprints, facial recognition, or geographic information. This multi-layered approach significantly bolsters the security of user authentication, making it more challenging for unauthorized access attempts to succeed.

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