Password Spraying vs. Brute Force: How Hackers Actually Break Into Accounts (And How to Stop Them)

If you’ve ever seen a “suspicious login attempt” alert, you’re not alone. Attackers are constantly trying to guess passwords. But they don’t all use the same playbook. Some go full throttle and try every possible combination until they hit a match. Others stay under the radar, testing just a handful of common passwords across thousands of accounts so they don’t trigger alarms.

Those two strategies—brute force and password spraying—sound similar. They’re not. And understanding the difference will help you build defenses that actually work.

In this guide, you’ll learn what sets these attacks apart, why password spraying is harder to detect, how leaked credentials supercharge both methods, and exactly what you can do to protect your accounts—at home and at work.

Let’s dig in. I’ll keep it plain-English and practical.

Brute Force Attacks: The “try everything” approach

When most people picture a hacker “guessing passwords,” they’re thinking of brute force. It’s the simplest idea: try every possible password until one works.

Here’s what that looks like in practice:

• Online brute force: An attacker targets a single account or a small set of accounts at a specific service (your email, your bank). They hammer the login with many guesses in a short time.
• Offline brute force: The attacker steals a database of password hashes from a breached site and cracks them on their own hardware. No rate limits. No lockouts. This is often faster and more dangerous.

Why brute force fails more often today:

• Services throttle or lock accounts after too many failed attempts.
• Many platforms detect rapid-fire attempts and block them.
• MFA can cut off access even if a password is guessed.

Still, brute force can work—especially when: – The target uses a short or common password. – Legacy protocols or endpoints bypass modern protections. – An attacker has the hash offline and can attempt billions of guesses per second.

Defense takeaway: Strong passphrases, MFA, and rate limiting make online brute force much harder. If you’re an organization, disable legacy authentication and enforce smart lockout policies.

What Is Password Spraying? The “few guesses, many accounts” attack

Password spraying flips the brute-force script. Instead of blasting one account with hundreds of guesses, an attacker tries one or two very common passwords across many different accounts. Then they wait a bit and try another common password, and so on.

Think of it like a thief walking down a street trying the same master key on every door, rather than picking one lock for hours.

A typical password spray looks like this:

• Pick a common or seasonal password: “Password123”, “Welcome1”, “Summer2025!”, “CompanyName2025!”
• Try it once against thousands of usernames (e.g., every employee in an organization).
• Pause to avoid rate limits. Rotate IPs. Try the next guess.

Why it works:

• Many people still use predictable passwords (seasonal numbers, “Welcome!”, “Spring2025!”).
• Single guesses across many accounts rarely trigger lockouts.
• Cloud logins are accessible from anywhere. Attackers don’t need to breach your network first.

Defense takeaway: Attackers don’t need to guess your exact password—just one that a few people reused. That’s enough to get a foothold in your environment.

Password Spraying vs. Brute Force: Key differences

Understanding the differences helps you tune your defenses:

• Target
• Brute force: One account, many guesses.
• Password spray: Many accounts, few guesses each.
• Pace and stealth
• Brute force: Noisy and fast. Easy to spot with lockouts and throttling.
• Password spray: Slow, distributed, often blends into normal traffic.
• Detection patterns
• Brute force: Repeated failures on the same account from a few sources.
• Password spray: Single failures across many accounts, often from many IPs.
• Resource needs
• Brute force: Needs consistent access to the target; may be blocked quickly.
• Password spray: Uses commodity infrastructure and can spread attempts over time.
• Likelihood of lockout
• Brute force: High.
• Password spray: Low.

For defenders, this means traditional lockout rules can stop brute force but may barely dent password spraying.

Why Password Spraying Is Harder to Detect

Here’s the tricky part: password spraying looks a lot like normal user behavior. A few bad passwords here and there? That happens every day.

Attackers take advantage of that ambiguity:

• They spread attempts over hours or days to avoid rate limits.
• They use many IP addresses (often from residential proxies) to avoid IP-based blocks.
• They pick passwords that are “plausible,” not random gibberish.
• They avoid logging in too aggressively to reduce suspicious patterns.

This is why detection needs to focus on patterns across users, not just per-account events. More on that below.

If you want a deeper technical read on how password spraying shows up in attacker playbooks, see MITRE ATT&CK’s entry for Password Spraying (T1110.003) here.

Real-World Trends You Should Know

A few data points drive home how common this is:

• Stolen credentials remain a top finding in breaches. The Verizon Data Breach Investigations Report has consistently shown credential-related attacks are a major driver of compromise. Check the latest DBIR here.
• Attackers favor cloud identity providers because they expose a single login surface for many accounts. It’s a perfect match for password spraying.
• Seasonal password patterns are gold for attackers. They know people rotate from “Summer2024!” to “Fall2024!” to “Winter2025!”—and they test those variations.

Here’s why that matters: even if only a small percentage of users pick weak, predictable, or reused passwords, a spray will often hit at least one. One successful login is all an attacker needs to pivot deeper.

Leaked Credentials Turbocharge Both Attacks

Now let’s talk about the fuel behind modern password attacks: data breaches.

When a site gets breached, its credential database—usernames, email addresses, often password hashes—can leak. Those credentials end up for sale or are dumped online. Attackers use them in three ways:

• Credential stuffing: Try known email/password pairs from one service at another (same user, same password). This relies on password reuse.
• Wordlists and mutations: Take leaked passwords and generate variations (“Summer2025!”, “Summer2025!!”, “Sumer2025!”). These lists make brute-force and spray attacks far more efficient.
• Pwned password checks: Attackers avoid guesses that are unlikely to work by focusing on known-compromised passwords.

Want to see if your email shows up in known breaches? Check Have I Been Pwned here. It’s a trusted, long-running public service.

Important: This is why security pros recommend screening new passwords against known-breached lists. NIST’s Digital Identity Guidelines explicitly call for this practice to reduce the use of compromised passwords. You can read NIST SP 800‑63B here.

How to Protect Your Accounts: Practical steps that work

Good news: a few smart moves dramatically reduce your risk—against both brute force and password spraying.

For individuals

• Use a password manager and unique passwords
• Let the manager generate and store strong, unique passwords for every site.
• If you prefer memory-based passwords, use a long passphrase (four or more random words).
• Turn on multi-factor authentication (MFA) everywhere
• Prefer app-based codes, device prompts, or security keys.
• If SMS is the only option, use it—it’s still much better than passwords alone.
• For sensitive accounts (email, financial), consider phishing-resistant security keys or passkeys.
• Embrace passkeys where available
• Passkeys replace passwords with modern, phishing-resistant authentication based on public-key crypto. Learn more via the FIDO Alliance here.
• Watch your sign-in alerts
• Review unusual login notifications and account activity.
• Change your password immediately if you see suspicious activity.
• Check exposure
• Periodically check your email addresses on Have I Been Pwned here.
• If found, change passwords on affected sites and anywhere you reused them.
• Don’t rotate passwords on a schedule
• Modern guidance (including NIST) discourages forced periodic resets. Change passwords if there’s evidence of compromise or if you used a weak one.

For organizations

You have more levers to pull—and you should use them.

• Enforce MFA broadly, security keys for high-risk roles
• Require MFA for all users. Use phishing-resistant methods (WebAuthn/FIDO2) for admins and executives.
• If your environment supports passkeys, roll them out thoughtfully for priority users.
• CISA offers simple guidance on enabling MFA here.
• Screen for weak and breached passwords
• Block common and compromised passwords during creation.
• Align with NIST SP 800‑63B’s guidance to check new passwords against known-breached lists here.
• Apply smart lockout and throttling
• Use progressive delays, not hard lockouts, to avoid denial-of-service risks.
• Consider “smart lockout” that tracks failures across IPs and time windows.
• Disable legacy and insecure protocols
• Turn off basic auth/legacy protocols (e.g., IMAP/POP without modern auth) that bypass MFA and modern protections.
• Use conditional access and risk-based policies
• Challenge or block logins based on risk signals: new device, new location, impossible travel, TOR/residential proxies, or known bad IPs.
• Harden your login surface
• Put login behind bot detection and rate limiting.
• Separate your public login endpoint from administrative portals.
• Monitor and detect spray patterns
• Aggregate authentication logs. Look for:
  • Many users with exactly one or two failures within a short window.
  • The same IP or ASN failing on many users.
  • Repeated failures from diverse IPs that share device fingerprints or user-agents.
• Use a SIEM to correlate across tenants, IPs, and time buckets.
• Protect administrative access
• Limit who can access admin portals. Require just-in-time elevation, separate admin accounts, and strong device posture.
• Educate users about predictable passwords
• Kill seasonal patterns (“Spring2025!”). Encourage long passphrases or manager-generated secrets.
• Drop forced rotation policies; reset only on risk or compromise.
• Prepare an incident response playbook
• Define thresholds for “suspected spray” events.
• Automate containment: temporary increased friction, forced MFA re-enrollment, targeted password resets, and post-login session review.

For implementation best practices, OWASP’s Authentication Cheat Sheet is a solid reference for developers and defenders alike. Read it here.

How to Spot Password Spraying and Brute Force in Your Logs

Security teams often ask, “What does a spray look like in data?” Here are practical signals:

• Indicators of password spraying
• A spike of single failed logins across many accounts within the same time slice.
• Failures originating from the same IP range, hosting provider, or ASNs.
• Slow, periodic pattern: one attempt per account every 30–60 minutes, then another round later.
• After a failure wave, a small number of successful logins to high-value accounts.
• Indicators of brute force
• Many rapid failures on one account from a small set of IPs.
• Credential validation against multiple endpoints for the same account (e.g., web and mobile).
• Account lockouts followed by fresh attempts from new IPs.
• Post-compromise clues (both methods)
• Immediate MFA registration changes, forwarding rules in email, or OAuth app grants.
• Access token reuse from unusual geographies (“impossible travel”).
• Privilege escalation attempts soon after first success.

Tip: Build detections that look both horizontally (across users) and vertically (per user over time). Many organizations only monitor per-account thresholds. That misses the “one-and-done” failures that define a spray.

For threat-modeling and mapping detections to known techniques, see MITRE ATT&CK’s password spraying entry here.

Brute Force vs. Spray: Choosing the right defenses

This is the part many teams miss: you need different lenses for the two threats.

• For brute force:
• Per-account lockouts and throttles
• MFA prompts on risky login behavior
• Device and network posture checks
• For password spraying:
• Cross-account anomaly detection
• IP/ASN reputation and velocity checks
• Detection of “low-and-slow” patterns
• Screening out weak/compromised passwords so “Welcome1” guesses never work

Both benefit from MFA. But here’s the nuance: MFA effectiveness depends on the method. Phishing-resistant methods (FIDO2/WebAuthn security keys or passkeys) provide the strongest defense. Consider enrolling executives, admins, and finance teams first. Google’s Advanced Protection Program is a good example for high-risk users here.

The future is passwordless (and that’s good)

We can’t talk about password attacks without addressing the elephant in the room: passwords themselves.

The industry is moving to passwordless sign-ins—particularly passkeys—because they:

• Eliminate shared secrets that can be guessed or stolen.
• Are phishing-resistant by design.
• Are easier for users when implemented well.

You’ll see more services offering “Sign in with a passkey.” Where possible, opt in. For orgs, pilot passkeys for a subset of users and measure support load and success rates before scaling. Learn the fundamentals from the FIDO Alliance here.

Quick recap and action plan

If you remember only five things, make them these:

1. Password spraying = few guesses across many accounts. Brute force = many guesses against one account.
2. Spraying is stealthy. It often evades per-account lockouts and simple rate limits.
3. MFA stops a huge portion of attacks—especially when you use security keys or passkeys.
4. Screen out weak and breached passwords. It kills the most common spray guesses before they start.
5. Monitor horizontally across users. You can’t catch a spray if you only look at one account at a time.

For more background and best practices: – NIST Digital Identity Guidelines: https://pages.nist.gov/800-63-3/sp800-63b.html – Verizon DBIR (latest trends): https://www.verizon.com/business/resources/reports/dbir/ – OWASP Authentication Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Authentication_Cheat_Sheet.html – Have I Been Pwned (exposure checks): https://haveibeenpwned.com/ – CISA on MFA: https://www.cisa.gov/mfa

FAQs: People also ask

Q: What’s the difference between password spraying, brute force, and credential stuffing? A: Brute force targets one account with many guesses. Password spraying targets many accounts with one or two common guesses each. Credential stuffing uses known email/password pairs from breaches and tries them across different services, betting on password reuse.

Q: Why is password spraying so effective? A: Because it avoids lockouts and detection. Many users still choose predictable passwords, and a single valid login can let attackers move laterally.

Q: Does MFA stop password spraying? A: Yes—especially phishing-resistant methods like security keys or passkeys. SMS-based MFA helps but can be phished or SIM-swapped. Use stronger factors where possible.

Q: Are long, complex passwords still necessary if I have MFA? A: Use both. MFA is a critical layer, but strong unique passwords (or passphrases) reduce risk from places where MFA isn’t available, and they prevent offline cracking if a database leaks.

Q: How long should a password be? A: Aim for at least 12–16 characters. A memorable passphrase (several random words) is both strong and easier to recall than a complex jumble.

Q: Should I change my passwords regularly? A: Don’t rotate on a fixed schedule. Change passwords if you believe they’re compromised, reused, or weak. Forced rotations often push users toward predictable patterns.

Q: Is SMS 2FA safe to use? A: It’s better than nothing. But app-generated codes, device prompts, and especially security keys/passkeys are stronger. Use the best option the site offers.

Q: How can I tell if my organization is being targeted by a password spray? A: Look for one or two failed logins across many different accounts within a short time window, often from related IP ranges. Cross-account analytics and a SIEM help.

Q: What if my site locks accounts after five failed attempts—does that stop sprays? A: Not necessarily. Sprays typically use one or two attempts per account to avoid lockouts. Add cross-account detection, IP reputation, and weak-password screening.

Q: Do CAPTCHAs help? A: They can slow bots but won’t stop determined attackers using human solvers or low-and-slow tactics. Use CAPTCHAs as part of a layered approach, not as your primary control.

Q: What’s the best first step if I’m starting from scratch? A: Turn on MFA for your email and primary cloud accounts. Then start using a password manager to create unique passwords everywhere. Those two steps cut most risk quickly.

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The bottom line: Hackers rely on the fact that people reuse passwords, pick predictable ones, and that most defenses only watch one account at a time. Flip that script. Turn on MFA, embrace passkeys, screen out weak and breached passwords, and monitor login patterns across users. You’ll shut down both brute force and password spraying before they start.

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