A brute force attack is a trial-and-error hacking method used to crack passwords, login credentials, and encryption keys by systematically trying possible combinations until the correct one is found. Brute force attacks are often automated with bots or scripts and can target everything from website login pages to SSH logins and API keys.
Instead of exploiting a software flaw, the attacker relies on repetition and computing power. Modern tools can try millions of combinations per second.
Advances in hardware, especially GPU acceleration, have made these attacks much faster.
While the technique itself is simple, it becomes powerful at scale. Despite being one of the oldest hacking methods, brute force is still effective because many users still use weak or reused credentials.
Why are Brute Force Attacks Dangerous?
Brute force attacks are dangerous because they target the primary gatekeeper of most systems: passwords. Given enough time and no protective controls, they can work against any password-based environment.
Once an attacker gets in, they may:
- Steal sensitive data (customer details, payment information, confidential files).
- Install malware, such as ransomware and backdoor access points.
- Take over accounts and reuse access elsewhere via credential stuffing.
- Hijack systems into a botnet, which can then be used to launch a wider disruption—including a DDoS attack.
- Cause financial loss and reputational damage.
The impact rarely stops at the initial breach. Organisations face downtime, regulatory scrutiny and loss of customer trust.
Many businesses manage this risk as part of a broader resilience strategy that includes technical controls and cyber insurance.
How Does it Work?
A brute force attack follows this sequence:
- The attacker chooses a target, such as a login page or SSH access point.
- They use software, scripts or bots to generate password guesses (or test stolen credentials).
- The system checks each attempt and returns success or failure.
- The attacker repeats attempts at speed until they find a working combination or are blocked.
Automated tools and GPU acceleration increase the number of attempts per second, so weak passwords fall quickly. Strong passwords, lockouts and rate limiting reduce the chances of success.
When brute force attacks target encrypted data, the length of the key, as well as the algorithm used, become critical. 128-bit encryption is considered secure, while 256-bit encryption would require an impractically large amount of computing power to successfully brute force.
Types of Brute Force Attack
- Simple brute force attacks – Try every possible password or PIN combination.
- Dictionary attacks – Test lists of common words and predictable phrases.
- Hybrid brute force attacks – Combine dictionary words with numbers and symbols to reflect real-world password habits.
- Reverse brute force attacks – Start with a known, or commonly used password and search for matching usernames.
While these methods differ slightly, they all rely on scale and repetition rather than cleverness. Their success rate is tied to password strength and the presence—or absence—of protective controls.
How to Prevent a Brute Force Attack
For organisations:
- Limit login attempts and introduce delays after failed logins.
- Lock accounts temporarily after repeated failed attempts.
- Deploy CAPTCHA challenges to block automated bots.
- Monitor networks for suspicious login activity in real-time.
- Enforce strong encryption standards and secure password hashing with salting.
- Block known malicious IP addresses.
Layered controls stop brute force attacks before they succeed. Rate limiting, monitoring and account lockouts slow down automated attacks and give security teams time to respond, while strong encryption reduces risk if data is exposed.
To strengthen your organisation’s cyber resilience, get in touch to see how Canopius can help with tailored cyber insurance solutions.
