A brute force attack is a basic hacking technique that targets systems or data by overwhelming authentication mechanisms with a high volume of login attempts. The attacker doesn't exploit a vulnerability or rely on social engineering - instead, they test passwords, passphrases, or encryption keys one at a time until something works. It's a direct computational approach meant to exhaust defenses rather than outsmart them.
What makes brute force different from other types of cyberattacks is its brute repetition. Malware injects code, phishing manipulates human behavior, but brute force needs no trickery and no system flaw and it relies entirely on automation and persistence to guess the right credentials. There’s no need for the victim to click anything or fall for a trap; success depends only on whether the system allows enough guesses.
At the heart of this is trial and error. Attackers use software to generate and test thousands, sometimes millions, of combinations. Whether it’s an online login, a secured database, or encrypted files, any password-protected system can be vulnerable if defenses are weak or passwords are predictable.
Despite being old, brute force is still a favorite among cybercriminals. Its appeal hasn't changed much - brute force works because it's simple, broadly useful, and still effective when passwords are weak or reused. Today, attackers often spread attempts across systems or IPs to avoid detection. And as long as people continue using easy or recycled passwords, brute force attacks will keep finding ways in. And according to a 2024 report from Verizon, 77% of attacks against web applications involve stolen credentials or brute force attacks.
Brute force attacks rely on systematic repetition. They work by guessing credentials or encryption keys until the correct one is found. Most are fully automated, using software to run massive numbers of login attempts or decryption trials. The attack doesn’t depend on flaws in the software - it depends on persistence, speed, and the absence of effective safeguards.
Targets vary, but the common thread is authentication. Passwords for login portals, email platforms, and CMS-based websites are frequent targets, especially when exposed to the internet. Remote access services like SSH, RDP, and VPN gateways are also regularly attacked due to the direct access they provide to internal systems. Encryption keys used for files or databases, Wi-Fi networks using WPA/WPA2 pre-shared keys, and cloud service credentials are similarly attractive. Less obvious but equally vulnerable are API keys and IoT devices - many of which use default or weak credentials.
The attack process involves generating and testing possible credential combinations. A basic brute force attack goes through every possible combination of characters. It works in theory but becomes useless fast if the password is long or complex. So attackers use shortcuts, like masks to define likely structures, or rules to tweak known passwords in ways real users might. These filters skip the junk and zero in on the patterns people actually use. Masks define likely patterns (like a capital letter followed by numbers), while rules apply transformations to common passwords (like replacing 'a' with '@'). These optimizations cut down time but don’t change the essential nature of the attack: guessing until something works.
Some brute force attacks are conducted online, directly against a login interface. Others happen offline - especially when attackers gain access to hashed passwords in a breach. In those cases, guesses are hashed and compared to the stolen hashes until a match is found. Tools like Hashcat and John the Ripper are optimized for this. In some cases, attackers use rainbow tables - precomputed lookup tables of hashes - to speed things up.
The ability to make repeated attempts is critical. Systems that don’t restrict login attempts or monitor access patterns are more likely to be compromised. Automation plays a central role here. Scripts and botnets., especially when traffic blends into normal network activity.
Several tools are commonly used to carry out brute force attacks. Hydra supports network protocols like SSH and FTP, enabling scripted login attempts. Hashcat specializes in offline cracking of password hashes and is highly optimized for GPU hardware. John the Ripper performs similar tasks, working across multiple platforms. Aircrack-ng targets Wi-Fi networks, capturing handshake data to brute-force WPA/WPA2 keys. L0phtCrack focuses on Windows environments, offering hash cracking and auditing. These tools are also used by penetration testers and red teams - under explicit authorization - as part of security assessments.
Brute force attacks are almost never manual. Typing in guesses by hand is neither fast enough nor scalable. Automation allows attackers to test credentials around the clock, across systems, and at speeds impossible for a human. This same approach is also applied to encrypted data (e.g. password-protected archives or secured volumes) where decryption keys are tested in sequence until one works. This scale and adaptability are what make brute force a persistent and evolving threat.
Brute force attacks rely on repetition, but the tactics used vary widely. Over time, attackers have refined their methods to match user behavior, system defenses, and the limits of computational efficiency. Below are the most common variants in use today.
Dictionary Attack: A dictionary attack doesn’t test every possible combination - it targets the most likely ones. Attackers rely on curated lists built from leaked credentials, common phrases, or predictable patterns. It’s faster than full brute force because it bets on human habits, not randomness. And while basic versions stick to exact matches, more sophisticated approaches expand on base entries with systematic tweaks, crossing into hybrid territory.
Brute force attacks succeed by exploiting gaps in authentication practices, poor password hygiene, and slow detection. The best defense is a layered one: built on strong credential policies, modern security measures, and attentive monitoring. Every organization, regardless of size, should assume these attacks are a matter of “when,” not “if.”
At their core, brute force attacks are about guessing - so the more unpredictable and complex the password, the longer an attacker has to work to get in. Short, recycled, or easy-to-guess passwords drastically reduce that time.
Start with length. Passwords should go beyond the usual 8-character minimum; 12 to 16 characters is the practical baseline today. Every extra character exponentially increases the attacker’s workload. Complexity helps - uppercase, lowercase, numbers, symbols - but randomness and unpredictability are what really make brute force attacks ineffective. Passphrases made of unrelated words offer a good balance of memorability and strength.
Each password must be unique. Credential stuffing thrives on reuse. Password managers help by generating and storing strong, unique credentials for every account, eliminating the need for users to compromise on complexity just to remember them.
Rather than forcing regular changes - which often lead to predictable patterns - organizations should block known breached passwords and enforce minimum length and entropy requirements.
Strong passwords slow brute force attacks, but stopping them entirely requires more.
Multi-Factor Authentication (MFA) has proven one of the most effective safeguards. Even if a password is cracked, MFA prevents access. Wherever possible, use phishing-resistant methods like hardware tokens.
CAPTCHA helps block automated tools. Deployed after a few failed logins, it adds friction without inconveniencing legitimate users. Rate limiting and account lockout policies further reduce risk by restricting repeated login attempts. Web application firewalls (WAFs) and intrusion prevention systems (IPS) screen for brute force signatures and throttle abusive patterns in real-time.
Because attackers often spread attempts across many IPs, detection needs to go beyond individual accounts. Network-level monitoring and threat intelligence feeds are critical for spotting coordinated campaigns early. Systems must never store passwords in plaintext. Instead, credentials should be hashed with slow, salted algorithms like bcrypt, scrypt, or Argon2. Encryption in transit and at rest closes off other brute-force-friendly gaps.
Zero Trust architecture helps reduce damage when attacks succeed. By treating every request as untrusted, segmenting access, and requiring re-authentication at session level, it limits lateral movement. Combine that with strong MFA and behavioral checks, and even a cracked password won’t provide attackers with unrestricted access.
And because most brute force attacks still rely on human errors, user training matters. People should know how to avoid credential reuse, spot phishing, and build strong passwords. Training should be specific, role-based, and reinforce the “why,” not just the “how.”
Good defenses aren’t enough - attackers get creative. Organizations need visibility and the ability to respond when brute force activity spikes.
Log collection is foundational. Authentication failures, spikes in login attempts, and suspicious IPs should feed into a SIEM or similar platform. Behavioral analytics can catch login anomalies. Performant XDR and MDR services enhance this with AI-based detection tuned to an organization’s environment.
IDS/IPS systems should alert on brute force indicators - like repeated account lockouts or sequential login attempts. Bitdefender’s Network Attack Defense adds another perimeter layer, blocking brute force payloads in real time.
Once an attack is detected, response speed matters. Key steps include:
Confirm the activity: Rule out false positives, check scope.
Contain: Block malicious IPs, restrict access, update firewall rules.
Reset credentials and enable MFA.
Preserve evidence for forensics.
Investigate, patch, and document.
Brute force attacks are illegal under nearly all cybercrime statutes. Attempting to access systems without authorization - even “just testing” - can lead to criminal charges. However, brute force simulations are valid when done with written consent, as part of authorized security assessments. Teams should also ensure their own controls - like IP logging - comply with data privacy regulations.
One of the earliest notable demonstrations of brute force cyber capabilities occurred in 1998, when the Electronic Frontier Foundation built “Deep Crack,” a machine designed to break the Data Encryption Standard (DES). Costing $250,000, it successfully cracked a DES-encrypted message in just 56 hours, highlighting the vulnerabilities of then-standard encryption methods. Over the decades, the scale of brute force attacks has changed. What was once limited by human input or basic scripts is now handled by automated systems running around the clock. Modern hardware can attempt billions of password combinations in seconds. Attackers often rely on networks of compromised machines to distribute the workload and evade detection.
In 2012, attackers breached LinkedIn and stole more than 100 million password hashes. These were stored using SHA-1 without salting, which made them easy to crack offline using standard tools. Once recovered, many of the passwords were used to break into accounts on other platforms because people had reused them.
In 2017, about 90 email accounts belonging to the UK Parliament were compromised. Passwords were weak, and multi-factor authentication wasn’t in place. Remote access had to be shut down while the issue was contained, and new access policies followed.
WordPress remains a frequent target because of its popularity and inconsistent security. One campaign used infected WordPress sites to run code in visitors' browsers. The infected browsers started sending login attempts to other sites, turning everyday web traffic into part of the attack. It masked where the brute force was coming from and made it harder to block.
The fallout depends on the target but is rarely minor. Businesses can face account breaches, regulatory trouble, and lasting reputational damage. Credentials stolen this way are often used in broader attacks like ransomware or system infiltration. For individuals, the damage can include financial loss, identity theft, or access to sensitive accounts being compromised.
Some attackers now use machine learning to generate passwords based on large datasets of previously leaked credentials. These guesses are more accurate than random strings and can get around basic complexity rules. AI also helps them avoid detection by mimicking human login patterns or bypassing CAPTCHA systems. Defenders use the same category of tools to catch unusual activity. Systems trained on login behavior can flag access attempts from odd locations or devices. Other platforms use pattern recognition to detect brute force attacks that stretch across services.
AI hasn't replaced traditional brute force tactics, it just makes them faster and harder to spot. That makes it more important to fix the gaps they target, especially around login and credential reuse.
Bitdefender GravityZone is a unified cybersecurity platform built to reduce exposure, detect brute force activity early, and contain attacks before they escalate. Its integrated tools provide coordinated defense across prevention, detection, and response.
Prevention and Exposure Reduction
Risk Management identifies exposed services, weak authentication, and misconfigurations that invite brute force attempts. Patch Management closes known vulnerabilities that attackers often target after gaining access. To limit credential-based risk, ITDR adds protection at the identity layer, flagging risky configurations and unauthorized changes before they’re exploited.
Detection and Response Capabilities
Network Attack Defense inspects traffic in real time and blocks brute force payloads across protocols like RDP, SMB, and SSH. EDR and XDR correlate events across endpoints to detect brute force patterns - such as repeated login failures, unusual access times, or credential abuse. For around-the-clock support, MDR analysts monitor for brute force activity and help contain threats through policy changes, credential resets, and live response.
Operational Visibility and Identity Protection
GravityZone brings all these tools under one roof, making it easier to see what's happening and apply consistent policies. Its Digital Identity Protection feature monitors for leaked credentials and issues early warnings, helping prevent their use in credential stuffing or brute force campaigns. PHASR strengthens defenses proactively by restricting access to tools and commands that attackers typically exploit, based on system behavior and context. If a breach occurs, Incident Advisor supports investigation and response, helping teams understand what happened, contain the impact, and harden defenses moving forward.
Unusual login activity is the first sign. You might see a surge in failed logins - either many on your account or multiple attempts from one IP across different usernames. Unexpected lockouts, logins from unknown locations, or alerts about password changes you didn’t request are also red flags
On some platforms, you’ll see login attempts at odd hours or from suspicious devices. If settings have changed or others are receiving messages from your account, it means the attacker got in. In enterprise environments, signs include authentication failures across systems, unusual bandwidth usage, or increased traffic to login endpoints.
MFA makes brute force attacks much less effective, since a stolen or guessed password alone isn’t enough. But it’s not foolproof.
Attackers use MFA fatigue - repeated push notifications until the user accepts - or phishing to trick users into sharing codes. SIM-swapping can intercept SMS-based tokens. Some even target session tokens or exploit insecure recovery processes to reset MFA entirely. Strong MFA setups like hardware keys (FIDO2) and tighter control over account recovery are better.
First, take it offline. Disconnect the device from your network to stop any external control or further spread.
Then, reset all associated passwords - especially if defaults were never changed. Check if the manufacturer issued any firmware updates, and consider reinstalling the firmware rather than just doing a factory reset. This cleans deeper, especially if the compromise went beyond user settings.
Monitor your network for other unusual activity. If the device was part of a botnet or backdoor, there may be signs on other connected systems. Change your Wi-Fi credentials if you think the exposure is broader, and segment your IoT devices from critical infrastructure going forward.
If the device doesn’t support these protections or shows repeat compromise, replacement might be the only option.