A brute force attack is a trial-and-error method used to gain unauthorized access to accounts, systems, and networks. Unlike more sophisticated cyber attacks that exploit software vulnerabilities, brute force attacks rely on persistence and raw computing power rather than technical exploits.
The attacker doesn’t need to find a clever backdoor. They simply try standard password combinations or personal identification numbers until something works. Some attackers focus on password combinations or personal information, such as birthdays, pet names, or anniversaries, that people commonly use as credentials.
Why these attacks remain effective
These attacks are often surprisingly effective, particularly against organizations that haven’t implemented proper security controls. At SecurityScorecard, we regularly observe the fallout from brute force hacking when analyzing the security posture of organizations across various industries. The damage from a successful brute force attack can be devastating, leading to data breaches, financial losses, and lasting reputational harm.
Understanding how these attacks work is the first step toward building effective defenses.
How brute force attacks work
The mechanics behind brute force methods are straightforward but powerful. An attacker uses automated software to generate and test password combinations at incredible speeds. Modern computing power allows these tools to attempt thousands or even millions of login attempts per second, depending on the target system’s defenses.
The password cracking process
When using brute force techniques, the attacker’s software starts with simple passwords and gradually increases complexity. It might begin with single characters, then two character types, then three, systematically working through every possible password until it finds the right one. The algorithm doesn’t need to be clever. It just needs to be persistent and have enough computing power behind it.
Factors that determine success
The time required to crack a password depends on several factors. Password length matters enormously. A four-character password might fall in seconds, while a twelve-character password with mixed character types could take centuries to crack using traditional brute force methods. This is why security professionals constantly emphasize the importance of strong password practices.
Modern attack tools and techniques
Automated brute force tools have become increasingly sophisticated. They can adapt their approach based on the target, adjusting for lockout policies and rate limits as needed. Some tools maintain lists of compromised credentials from previous breaches, while others generate password guesses based on publicly available information about the target. The goal is always the same. Find the correct password with as little effort as possible.
Common types of brute force attacks
Not all brute force techniques are created equal. Attackers have developed several variations to make their efforts more efficient and more challenging to detect.
Simple brute force attacks
A simple brute force attack is the most basic form of brute force hacking. The attacker’s software attempts every possible combination without any shortcuts or intelligent guessing. Simple brute force methods are most effective against short passwords or weak password implementations. While this form of attack is thorough, it’s also the slowest approach and most likely to trigger security alerts due to the sheer number of password attempts required to succeed.
Dictionary attacks
A dictionary attack represents a smarter approach. Instead of trying every possible combination, a dictionary attack uses a predefined list of common passwords and words. This attack method recognizes that most people choose predictable passwords like “password123” or “qwerty.” The attacker runs through this dictionary of likely candidates before resorting to more exhaustive methods.
Dictionary attacks are often the first step in any brute force campaign because they can find the correct password quickly if the target uses common password choices. These attacks exploit human nature. People want passwords they can remember, so they choose dictionary words, names, dates, and other predictable patterns.
A well-maintained dictionary might contain millions of entries, including leaked passwords from previous data breaches, common substitutions, and culturally relevant terms.
Hybrid brute force attacks
A hybrid brute force attack combines a dictionary attack with traditional brute force methods. The attack combines dictionary words with numbers and special characters. For example, it might take the word “password” and try variations like “password1,” “password!” or “p@ssword.” This hybrid attack approach is remarkably effective because it exploits how people actually create passwords. They often start with a base word and add predictable modifications.
Reverse brute force attacks
A reverse brute force attack flips the traditional approach on its head. This is an attack where the attacker starts with a known password and tests it against multiple usernames, rather than trying multiple passwords against one account. Instead of trying multiple passwords against one account, they try one password against multiple usernames across an entire system. This works because many people use the same password across different services. When credentials leak from one data breach, attackers can use password spraying techniques to test those passwords against entirely different platforms.
Credential stuffing
Credential stuffing warrants special attention because it has become increasingly common. Attackers take username and password combinations stolen from previous breaches and automatically test them against other sites. Since so many people use the same password across multiple accounts, credential stuffing attacks often succeed.
Our research at SecurityScorecard consistently shows that credential stuffing represents a significant portion of automated brute force attempts we observe. The attack exploits a fundamental weakness in human behavior. People reuse passwords because creating and remembering unique credentials for every service feels overwhelming.
Brute force attacks can also target enterprise systems, where employees may use corporate credentials on personal accounts that are later compromised. Organizations need continuous monitoring of their supply chain to detect when vendor credentials have been compromised.
The third-party breach connection
According to our 2025 Global Third-Party Breach Report, 35.5% of all data breaches now originate from third-party compromises, up from 29% the previous year. Many of these breaches stem from credential-based attacks where attackers use stolen login information to access vendor systems and then pivot to their customers’ networks.
The UNC5537 threat group, for example, launched a campaign against Snowflake cloud services that became the second most common third-party attack vector in 2024, specifically targeting accounts that lacked multi-factor authentication.
Password spraying
Password spraying takes a careful approach to avoid detection. Rather than making thousands of password attempts against a single account, the attacker tries a few common passwords against many accounts simultaneously. This technique helps evade lockout policies that limit the number of failed login attempts per account.
Password spraying is particularly effective in enterprise environments where attackers can identify valid usernames through reconnaissance. The attacker might try passwords like “Summer2024!” or “Company123” against hundreds of employee accounts, staying just below the threshold that would trigger lockouts. Network security teams often struggle to detect password spraying because the failed login attempts are spread across many accounts rather than concentrated on one.
Real world password spraying at scale
Our STRIKE threat intelligence team recently uncovered a massive botnet of over 130,000 compromised devices conducting large-scale password spraying attacks against Microsoft 365 accounts. The attackers exploited non-interactive sign-ins with Basic Authentication, a technique that bypasses modern login protections and evades MFA enforcement.
By using stolen credentials from infostealer logs, the botnet systematically targeted accounts across multiple organizations globally. This real-world example illustrates the sophistication of password spraying campaigns and highlights the need for organizations to monitor not only interactive logins but also service account authentication patterns.
Motives behind brute force attacks
Understanding why attackers use brute force attacks helps organizations prioritize their defenses. The motivations vary widely.
Financial gain and data theft
Financial gain drives most attacks. Once inside a system, attackers can steal sensitive data, deploy ransomware, or access financial accounts directly. Brute force attackers targeting e-commerce sites might be after customer credit card information, while those hitting corporate networks often seek access to valuable intellectual property.
Establishing persistent access
Some attacks aim to establish persistence. After a successful brute force attack, hackers may install backdoors that give them ongoing access even if the original vulnerability gets patched. They might also use compromised accounts to launch attacks against other targets, making attribution more difficult.
Corporate espionage and nation state activity
Corporate espionage represents another motivation. Competitors or nation states might use brute force hacking to gain unauthorized access to trade secrets, strategic plans, or sensitive communications. These attackers often target specific high-value accounts rather than attacking indiscriminately.
Hacktivism and disruption
Hacktivism and simple vandalism round out the list. Some attackers just want to deface websites, disrupt services, or make political statements. The tools for brute force attacks are widely available, making this type of attack accessible even to less sophisticated threat actors.
How to prevent brute force attacks
Organizations can take concrete steps to protect against brute force attacks. The good news is that these defenses work.
Implement strong password policies
The first line of defense is eliminating weak passwords entirely. Users should create passwords that are at least twelve characters long and include multiple character types. Ban common passwords and dictionary words. Consider using password managers to help employees maintain unique, complex credentials for every system.
When people use password managers, they don’t need to remember every password combination, which eliminates the temptation to reuse simple passwords. A strong password should resist both simple brute force attempts and dictionary attacks. The combination of length, complexity, and uniqueness makes brute force password cracking impractical.
Organizations should also implement checks that prevent users from choosing passwords that appear in known breach databases.
Deploy multi-factor authentication (MFA)
Multi-factor authentication effectively stops most brute force attacks. Even if an attacker discovers the correct password, they still can’t gain unauthorized access without the second factor. This might be a code sent to a phone, a biometric scan, or a hardware token. We consistently recommend multi-factor authentication as one of the most effective controls against brute force and many other attack methods.
Watch for MFA bypass techniques
However, organizations should be aware that sophisticated attackers are finding ways to bypass MFA in certain configurations. Our STRIKE team discovered that the massive M365 botnet we tracked was specifically exploiting non-interactive sign-ins to evade MFA enforcement.
Legacy protocols like POP, IMAP, and SMTP often don’t trigger MFA challenges, creating blind spots that attackers actively exploit. To maximize protection, organizations should disable Basic Authentication, implement Conditional Access Policies, and monitor non-interactive sign-in logs alongside traditional authentication monitoring.
Limit the number of login attempts
Account lockout policies that limit the number of failed login attempts make traditional brute force attacks impractical. After a set number of incorrect password attempts, the system should lock the account or introduce delays between attempts. This dramatically increases the time required to crack a password through brute force methods. Just be careful to implement these controls in ways that don’t create denial of service vulnerabilities.
Monitor for suspicious activity
Detection matters as much as prevention. Monitor authentication logs for signs of brute force attempts. These include multiple failed login attempts from a single IP address, login attempts for non-existent usernames, and unusual patterns in password attempts. SecurityScorecard’s threat landscape monitoring helps organizations identify when their external systems show signs of being targeted by automated brute force campaigns.
Protect password hashes
If attackers gain access to password hashes, they can attempt offline brute force attacks without worrying about lockout policies. Use strong, modern hashing algorithms with appropriate salting. This ensures that even if password data is stolen, attackers can’t easily crack passwords to find the correct password.
Consider rate limiting and CAPTCHAs
Additional technical controls can slow down or stop automated brute force tools. Rate limiting restricts the number of requests that can come from a single source. CAPTCHAs require human interaction that automated tools can’t easily replicate. These measures won’t stop a determined attacker entirely, but they significantly increase the cost and effort required.
How SecurityScorecard helps protect your organization
Your security is only as strong as your weakest link, and that often includes your vendors. SecurityScorecard continuously monitors the external attack surfaces of organizations worldwide, identifying vulnerabilities that brute force attackers commonly target.
Visibility into authentication weaknesses
Our security ratings offer visibility into authentication weaknesses, exposed login panels, and other factors that increase the risk of brute force attacks. We help you identify which of your vendors might be susceptible to these attacks before they become your problem through our third-party risk management solutions.
Take action now
The threat from brute force attacks isn’t going away. Attackers continue to refine their techniques, and computing power continues to become increasingly affordable. But organizations that implement proper controls can dramatically reduce their risk. Start by assessing your current exposure, then systematically address the gaps.
Learn how brute force attacks and other cyber threats could be affecting your organization’s security posture. Request a demo of SecurityScorecard’s platform to see your attack surface as attackers see it.
