What is a Brute-Force Attack?

A brute-force attack is a type of cyberattack that involves an attacker attempting to guess a password or encryption key by trying every possible combination until the correct one is found.

Brute-force attacks remain a popular choice among cybercriminals due to their simplicity and effectiveness, despite being one of the most straightforward and time-consuming methods of attack. These attacks pose a significant threat to the security of individuals, organizations, and governments worldwide, and are by far the most common threat vector used to target cloud service providers, comprising 51% of all attacks in the first quarter of 2022, according to analysis from Google Cloud. This article will discuss the different types of brute-force attacks, popular methods used to carry out these attacks, and the tools and techniques you can use to protect against them.

What Is a Brute-Force Attack?

A brute-force attack is a type of cyberattack that systematically tries all possible combinations of characters in order to guess a password or encryption key. Attackers use automated software to test thousands, or even millions, of potential password or key combinations until they find the correct password or key. Brute-force attacks are often used by cybercriminals as a way to gain access to secure systems like encrypted data or online accounts, and can be very effective in guessing weak or simple passwords. They can also be very time-consuming and resource-intensive for the threats actors behind them, but are still a very popular attack method due to the valuable sensitive data they often yield, and are becoming increasingly common with the shift to remote and hybrid work environments. Hackers can benefit from brute-force attacks by stealing personal data, profiting from ads or collecting activity data, spreading malware to cause disruptions, hijacking systems for malicious activity, or damaging a website’s reputation.

There are multiple types of brute-force attacks. They include:

• Simple Brute Force Attacks: In this type of attack used to guess simple passwords, hackers attempt to logically guess credentials without the assistance of software tools or other means. 
• Dictionary Attacks: In a dictionary attack, a hacker chooses a target and runs possible passwords against that username. Dictionary attacks are the most basic brute force attack tool, and are often used as a key part of password cracking.
• Hybrid Brute Force Attacks: In these attacks used to figure out combination passwords that mix common words with random characters, hackers blend outside means with their logical guesses to attempt a break-in. A hybrid attack typically mixes dictionary and brute-force attacks. 
• Reverse Brute Force Attacks: A reverse brute force attack reverses the attack strategy. The attacker starts with a known password and then searches millions of usernames until they find a match. In many cases, cybercriminals start with leaked passwords that are available online from existing data breach.
• Credential Stuffing: Threat actors recognize that users frequently reuse login information across many websites and exploit this poor security practice. If a malicious actor has a username-password combination that works for one website, they’ll try it in many others as well. 

Common Tools Used in Brute-Force Attacks

The most common tools leveraged in brute-force attacks are the ones that help automate the process of guessing credentials and finding combinations. These tools can find weak passwords, decrypt password data, run character combinations, and launch dictionary attacks. Some of the most popular brute-force attack tools include:

• John the Ripper: John the Ripper is an open-source tool that enables users to deploy dictionary attacks and detect weak passwords through various cracking and decryption techniques.
• Aircrack-ng: Aircrack-ng is an open-source penetration testing tool focused on wireless network security. It enables users to run dictionary attacks against network protocols.
• Hashcat: Hashcat is a penetration testing platform that allows hackers to use known "hashes", a password that's run through a formula and converted to a string of random characters that is always the same length regardless of how much data the password contains. With this known data, they can use Hashcat to run dictionary or rainbow table attacks to reverse the password back to readable text.

Are You At Risk?

If you are like the majority of users and choose weak passwords (those that are short and easy to remember, without a combination of upper case, lower case, numeric, and special characters to add a layer of complexity), then you face a heightened risk of suffering a brute-force attack. 83% of Americans create weak passwords in terms of length (less than 10 characters) and character complexity (only numbers and letters), and 53% use the same passwords across accounts. Many  users’ account credentials also include personal information that can be easily accessed online, such as their name, birth date, or hobbies. These factors add a level of simplicity and convenience for cybercriminals looking to use brute-force attacks to steal proprietary information or data to sell on the dark web, lock out administrators until they receive a ransom payment, or infect systems with malware for economic, political, or social reasons. 

If you are targeted in a brute-force attack, there is an extremely high likelihood that it will be successful and you will suffer the above consequences. Theoretically, brute force attacks have a 100% success rate for attackers, although adversaries may have to wait years for their automated systems to correctly guess a complex password.

Prevention & Mitigation Strategies

Although brute-force attacks are overall very effective in guessing credentials, by engaging in the following cybersecurity best practices, you can significantly reduce the likelihood of falling victim to an attack:

• Use strong, complex passwords (greater than 10 characters in length and a combination of upper case, lower case, numeric, and special characters).
• Use multi-factor authentication (MFA).
• Limit login attempts and disable root SSH logins.
• Implement IP address monitoring.
• Use a CAPTCHA.
• Use a web application firewall (WAF).
• Enforce the use of secure, encrypted connections among employees.
• Provide mandatory cybersecurity awareness training.
• Use threat detection and network security tools.
• Protect email accounts with a comprehensive, fully-managed email security solution.

T-Mobile IT Servers Breached with Brute-Force Attacks, Personal Information of 54 Million People Stoles

In 2021, malicious hackers used brute-force attacks to breach T-Mobile IT servers, resulting in the theft of 54 million people’s personal data including social security numbers, names, phone numbers and addresses, as well as device identifiers and PINs for certain accounts. Current, former and prospective T-Mobile customers were among those with personal information stolen. This attack led to harsh criticism of T-Mobile’s security. The hacker who took responsibility for the breach, 21-year old John Binns, even said that T-Mobile’s “security is awful.” Binns admitted to finding an unprotected router after using a publicly available tool to search weak spots in T-Mobile’s known Internet addresses. This access point allowed him to illegally hack into a data center, where he then gained access to over 100 servers via stored credentials and about a week later cracked into the T-Mobile customer data files.

Keep Learning About Brute-Force Attacks

Brute force attacks are used to gain unauthorized access to a system by taking advantage of common credential vulnerabilities such as poorly designed, recycled, and stagnated passwords.

Hackers will use various brute-force methods, offline and online approaches, and sophisticated tools to obtain correct credential information quickly. Luckily, by implementing the tips and best practices shared in this article, you can greatly reduce your chances of suffering the damaging consequences of a brute-force attack.

• Learn more about effectively protecting your business from ransomware.
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