Passwords remain one of the most frequently targeted parts of an organization's security infrastructure. Attackers do not always need sophisticated malware, zero-day vulnerabilities, or advanced exploitation techniques to gain access to a network. In many cases, they simply attempt to authenticate using passwords that users are likely to have chosen.

Two important password-guessing techniques are password spraying and brute-force password attacks.

Although both attacks involve trying passwords against user accounts, their strategies are significantly different:

• Password spraying: tries a small number of common passwords against a large number of accounts.
• Traditional brute-force attack: tries a large number of passwords against one or a small number of accounts.

Understanding this distinction is important because traditional account-lockout policies may slow down brute-force attacks while being less effective against carefully executed password spraying.

What Is Password Spraying?

Password spraying is a credential attack in which an attacker attempts one or a small number of commonly used passwords against many different user accounts.

Instead of repeatedly attacking a single account, the attacker distributes authentication attempts across numerous usernames.

For example, suppose an organization has accounts such as:

• user1@company.com
• user2@company.com
• accounts@company.com
• sales@company.com
• support@company.com

An attacker might test a commonly used password against all these accounts. Later, the attacker may try another common password.

The objective is to discover an account whose owner happens to be using one of the passwords being tested.

The technique is called password spraying because passwords are effectively "sprayed" across a collection of accounts.

Why Do Attackers Use Password Spraying?

A major advantage of password spraying from an attacker's perspective is that it can reduce the likelihood of triggering traditional account-lockout controls.

Consider a system configured to lock an account after five consecutive incorrect passwords.

A conventional brute-force attack might produce:

Account A → Wrong Password 1 → Wrong Password 2 → Wrong Password 3 → Wrong Password 4 → Wrong Password 5 → Account Locked

Password spraying instead distributes the attempts:

Password 1 → Account A, Account B, Account C, Account D...

Each individual account receives relatively few failed attempts.

A sophisticated attacker may also wait between rounds, making the activity harder to distinguish from normal authentication failures.

This behavior is sometimes described as a low-and-slow authentication attack.

How Does Password Spraying Work?

A typical password-spraying campaign can involve several stages.

1. Username Discovery

The attacker first needs potential usernames.

Usernames may be discovered from publicly available information, compromised databases, company websites, social networks, predictable email naming conventions, or other exposed information.

For example, organizations frequently use predictable formats such as:

firstname.lastname@company.com

Once an attacker understands the naming convention, potential usernames may become easier to predict.

2. Selection of Likely Passwords

Instead of testing millions of passwords, the attacker focuses on passwords that users are statistically more likely to choose.

These may include predictable patterns based on:

• seasons
• years
• company names
• locations
• departments
• keyboard patterns
• simple password conventions
• previously leaked password patterns

The security problem is therefore not simply password length. Predictability and password reuse are major risks.

3. Distributed Authentication Attempts

The attacker attempts a password against numerous accounts.

If unsuccessful, another password may be tested later.

Attackers may intentionally reduce the rate of attempts to avoid:

• account lockouts
• IP-based blocking
• rate limits
• automated security alerts
• intrusion detection rules

4. Successful Authentication

If one account accepts the password, the attacker may gain legitimate-looking authenticated access.

Depending on the compromised account, this could provide access to:

• email
• cloud storage
• internal applications
• VPN services
• remote desktops
• shared documents
• business systems

5. Further Account Compromise

Once access is obtained, an attacker may attempt additional activities such as stealing information, searching email, impersonating the account owner, identifying privileged accounts, establishing persistence, or attempting lateral movement.

What Is a Brute-Force Password Attack?

A brute-force password attack is an attack in which large numbers of possible passwords are systematically attempted until the correct credential is discovered or the attack is blocked.

A simplified attack pattern might look like:

Target Account → Password 1 → Password 2 → Password 3 → Password 4 → ...

Depending on the circumstances, password guessing may involve extremely large numbers of attempts.

The practicality of brute forcing depends heavily on whether the attacker is attacking a live login service or has obtained password hashes for offline cracking.

Online vs. Offline Brute-Force Attacks

This distinction is extremely important.

Online Brute Force

An online attack submits authentication requests directly to a live service such as:

• website login
• VPN
• Remote Desktop Gateway
• SSH server
• cloud service
• email portal

Online attacks are relatively constrained because defenders can implement:

• rate limiting
• account lockouts
• IP reputation controls
• CAPTCHA
• MFA
• smart lockout
• conditional access
• automated threat detection

Every authentication attempt may also generate a security log.

Offline Password Cracking

Offline cracking occurs when an attacker obtains password hashes or another password-verification database and attempts password candidates locally.

This can be considerably more dangerous because the attacker may no longer be constrained by the organization's normal login controls.

Account lockout, CAPTCHA, IP blocking, and login rate limiting generally cannot stop an attacker from testing password candidates against stolen hashes offline.

Protection therefore depends heavily on secure password storage, strong password hashing, unique strong passwords, and prevention of credential database compromise.

Types of Brute-Force Password Attacks

The term "brute force" is sometimes used broadly for several password-guessing techniques.

Pure Brute Force

The attacker systematically tests possible character combinations.

As password length and randomness increase, the number of possible combinations grows dramatically.

This is why long, randomly generated passwords are substantially more resistant to exhaustive guessing.

Dictionary Attack

Instead of testing every possible combination, a dictionary attack tests likely passwords from prepared lists.

These lists may contain:

• common passwords
• dictionary words
• predictable patterns
• passwords found in previous breaches
• variations of known password structures

Dictionary attacks can therefore be significantly more efficient than exhaustive brute force against weak human-generated passwords.

Hybrid Password Attack

A hybrid attack combines dictionary words with predictable modifications.

For example, an attacker may test variations involving:

• capitalization
• numbers
• years
• prefixes
• suffixes
• symbol substitutions

This is one reason simply adding a number or symbol to a predictable word does not necessarily create a strong password.

Credential Stuffing

Credential stuffing is related but technically different.

In credential stuffing, attackers use username/password combinations obtained from previous data breaches and attempt them against other services.

Credential stuffing succeeds primarily because people reuse passwords.

Password Spraying

Password spraying is another password-guessing technique, but it reverses the traditional brute-force pattern.

Rather than testing many passwords against one account, it tests a small number of passwords against many accounts.

Password Spraying vs. Brute Force

Characteristic	Password Spraying	Traditional Brute Force
Primary strategy	Few passwords against many accounts	Many passwords against one/few accounts
Main objective	Find users with predictable passwords	Discover a target account's password
Account lockout risk	Usually lower	Usually higher
Attack speed	Often deliberately slow	Can be rapid
Detection	Can be difficult if distributed	Often easier because of repeated failures
Typical target	Large user population	Specific account
Key defense	MFA, password controls, identity analytics	MFA, rate limiting, lockout, strong passwords
Common indicator	Same password-pattern attack across users	Large failures against one username

Why Password Spraying Can Be Dangerous

Password spraying takes advantage of an important weakness in many organizations: some users still choose predictable passwords.

An organization might have hundreds or thousands of accounts. Even if only a small percentage use weak passwords, spraying may identify one of them.

One compromised account can potentially become an entry point into the organization.

The consequences depend on the account's privileges and the security architecture around it.

Possible consequences include:

• unauthorized mailbox access
• confidential data exposure
• cloud file theft
• business email compromise
• impersonation
• fraudulent payment requests
• unauthorized VPN access
• remote network access
• lateral movement
• privilege escalation attempts

Password Spraying Against Microsoft 365 and Google Workspace

Cloud productivity platforms are attractive targets because a compromised account may provide access to email, files, contacts, calendars, and business information.

Organizations using platforms such as Microsoft 365 or Google Workspace should therefore avoid relying solely on passwords.

Strong identity protection should include:

MFA + secure password policy + modern authentication + sign-in monitoring + access controls

Administrators should also investigate suspicious login activity, unusual geographic access, unfamiliar devices, abnormal IP addresses, repeated authentication failures, and unexpected MFA activity.

Password Spraying Against Remote Desktop and VPN Services

Internet-exposed authentication services can receive automated password attacks.

Particular attention should be paid to:

• RDP
• RD Gateway
• VPN gateways
• SSH
• remote administration portals
• webmail
• firewall management interfaces

Directly exposing administrative services to the public Internet unnecessarily increases attack surface.

Where remote access is necessary, organizations should use appropriate architectures such as VPNs, RD Gateway, Zero Trust access solutions, MFA, network restrictions, and monitored access controls.

How Can Password Spraying Be Detected?

Password spraying can be harder to identify than straightforward brute force because individual accounts may receive relatively few failed attempts.

Detection should therefore look across multiple accounts, IP addresses, devices, and time periods.

Important warning signs include:

One Source Attempting Many Accounts

A single IP address generating authentication failures for numerous usernames can indicate spraying.

Similar Failure Patterns Across Multiple Users

Security monitoring systems should correlate authentication failures across accounts instead of evaluating each user independently.

Unusual Geographic Locations

Authentication attempts from countries or regions where the organization normally has no users may warrant investigation.

Geographic information alone, however, should not be treated as proof of an attack because VPNs, mobile networks, proxies, and cloud services can affect apparent location.

Successful Login Following Multiple Failures

A successful authentication event following a suspicious series of failures deserves additional investigation.

Unusual Login Times

Access at times inconsistent with normal user activity may contribute to a broader risk assessment.

Unknown Devices

A successful authentication from a previously unseen device can be an important indicator, particularly when combined with other anomalies.

Detecting Traditional Brute-Force Attacks

Traditional online brute-force attacks frequently generate clearer patterns.

Security teams should monitor for:

• hundreds of failed attempts against one account
• repeated authentication failures from one IP
• repeated attempts against administrator accounts
• unusually high login frequency
• lockout events
• failed RDP authentication
• failed VPN authentication
• failed SSH logins
• repeated web application login failures

Centralized log collection makes these patterns easier to identify.

A SIEM or identity security platform can correlate events across systems and generate alerts.

How to Prevent Password Spraying and Brute-Force Attacks

Effective protection requires multiple controls rather than relying on a single password policy.

1. Enable Multi-Factor Authentication

MFA is one of the most important defenses against password-based account compromise.

Even if an attacker discovers the password, an additional authentication factor can prevent direct access.

Where possible, organizations should prefer phishing-resistant authentication methods, including security keys, passkeys, or other modern cryptographic authentication technologies.

MFA should be prioritized for:

• administrators
• Microsoft 365 users
• Google Workspace users
• VPN users
• remote-access accounts
• finance users
• executives
• privileged users

Ideally, MFA should protect all accounts capable of remote authentication.

2. Eliminate Weak and Compromised Passwords

Organizations should prevent users from selecting passwords known to be weak or compromised.

Modern password policies should emphasize:

• sufficient length
• uniqueness
• resistance to guessing
• blocking commonly used passwords
• blocking known compromised passwords

Complexity rules alone are insufficient if users respond by creating predictable patterns.

3. Use Unique Passwords

Every important account should have a unique password.

Password reuse dramatically increases the effectiveness of credential stuffing and other credential attacks.

A password manager can help users generate and securely maintain unique passwords.

4. Implement Appropriate Account Lockout Controls

Account lockouts can help stop rapid brute-force attacks.

However, excessively aggressive lockout policies can create a denial-of-service problem because attackers may intentionally lock legitimate users out.

Modern adaptive or smart-lockout mechanisms are preferable where available.

5. Implement Rate Limiting

Authentication services should restrict excessive login attempts.

Rate limiting can slow automated attacks sufficiently to make brute-force guessing impractical.

6. Use Conditional Access and Risk-Based Authentication

Modern identity platforms can evaluate contextual signals such as:

• location
• IP reputation
• device state
• sign-in risk
• user risk
• application
• authentication method

High-risk authentication attempts can then be blocked or challenged with additional verification.

7. Disable Unnecessary Legacy Authentication

Older authentication mechanisms may not support modern security controls such as MFA.

Organizations should identify and disable unnecessary legacy protocols wherever operationally possible.

8. Protect Administrator Accounts

Privileged accounts require stronger controls than ordinary user accounts.

Recommended practices include:

• separate administrator accounts
• strong unique credentials
• MFA
• restricted login locations
• minimal privileges
• dedicated administrative devices where practical
• comprehensive auditing

An administrator should not routinely perform normal email and web browsing using a highly privileged account.

9. Secure Remote Desktop

Organizations using RDP should avoid unnecessarily exposing TCP port 3389 directly to the public Internet.

Better approaches include appropriately configured:

• VPN
• RD Gateway
• MFA
• firewall allowlists
• Zero Trust access
• secure remote-access gateways

RDP logs should also be monitored for repeated authentication failures.

10. Monitor Authentication Logs

Authentication logs should be retained and reviewed.

Useful information includes:

• username
• source IP
• timestamp
• authentication result
• device
• application
• location indicators
• authentication method
• MFA result

Centralized monitoring allows patterns involving multiple accounts to be identified.

11. Use SIEM and Automated Detection

Larger environments should consider centralized security monitoring.

Detection rules can identify situations such as:

One IP → failures against many usernames

or:

One username → unusually large number of failures

These patterns can help distinguish password spraying from conventional brute force.

12. Restrict Access by Network Where Appropriate

Administrative systems and sensitive applications should not necessarily accept authentication attempts from every Internet address.

Depending on business requirements, organizations can use:

• firewall rules
• VPN requirements
• IP allowlists
• geographic restrictions
• private networks
• Zero Trust access controls

13. Adopt Passwordless Authentication Where Practical

Passkeys, FIDO2 security keys, and other cryptographic authentication technologies can significantly reduce dependence on passwords.

Passwordless systems can make conventional password spraying impossible for accounts where no reusable password is accepted for authentication.

What Should You Do If Password Spraying Is Detected?

A suspected password-spraying incident should be treated as an identity-security event.

Security teams should determine:

1. Which accounts were targeted?
2. Which source IP addresses were involved?
3. Did any authentication attempt succeed?
4. Was MFA successfully completed?
5. Were privileged accounts targeted?
6. Were any suspicious sessions established?
7. Was email, cloud storage, VPN, or another system accessed?
8. Were security settings or authentication methods modified?

If compromise is suspected, appropriate incident-response procedures may include terminating suspicious sessions, resetting affected credentials, reviewing MFA methods, checking for persistence, examining mailbox or application changes, reviewing audit logs, and investigating related accounts.

Password changes should preferably be performed from a trusted device.

Why MFA Is So Important

Consider this simplified security model:

Password only

Attacker obtains password → authentication may succeed.

Password + MFA

Attacker obtains password → additional verification is still required.

MFA therefore changes a stolen password from being the complete authentication secret into only one component of the authentication process.

However, not every MFA method provides equal resistance to phishing and social engineering.

Where supported, organizations should move toward phishing-resistant MFA and passwordless authentication rather than depending exclusively on approval notifications or one-time codes.

Example Security Architecture

A well-protected business environment might use:

Internet

↓

Firewall / Secure Access Layer

↓

Identity Provider

↓

MFA + Conditional Access + Risk Analysis

↓

VPN / RD Gateway / Cloud Application

↓

Authorized User

↓

Centralized Authentication Logging

↓

SIEM / Security Monitoring

This layered architecture means that knowing a password alone should not automatically provide access to critical resources.

Password Spraying, Brute Force, and Credential Stuffing Compared

Attack	Credentials Used	Typical Target Pattern	Main Weakness Exploited
Password Spraying	Few common passwords	Many accounts	Predictable passwords
Brute Force	Many generated passwords	One/few accounts	Weak/short password
Dictionary Attack	Word/password lists	One/few accounts	Human password patterns
Credential Stuffing	Previously stolen username/password pairs	Many services	Password reuse

Recognizing these distinctions helps security administrators build more accurate detection rules.

Recommended Business Security Checklist

Businesses should implement the following baseline protections:

• Enable MFA for all remotely accessible accounts.
• Prefer phishing-resistant MFA where available.
• Require sufficiently long and unique passwords.
• Block common and known compromised passwords.
• Deploy password managers where appropriate.
• Monitor authentication failures.
• Alert on failures distributed across many usernames.
• Protect administrator accounts separately.
• Disable unnecessary legacy authentication.
• Secure RDP, VPN, SSH, and administrative interfaces.
• Avoid unnecessary direct Internet exposure.
• Apply rate limiting and smart lockout.
• Implement conditional access where supported.
• Review suspicious successful logins.
• Monitor changes to MFA and recovery methods.
• Maintain centralized security logs.
• Regularly review inactive accounts.
• Immediately disable accounts that are no longer required.
• Educate employees about password reuse.
• Develop an incident-response procedure for account compromise.

Frequently Asked Questions (FAQ)

1. What is password spraying?

Password spraying is an authentication attack in which a small number of commonly used or predictable passwords are attempted against many user accounts.

2. What is a brute-force password attack?

A brute-force password attack attempts numerous password possibilities against a target account until the correct password is found or defensive controls stop the attack.

3. What is the main difference between password spraying and brute force?

Password spraying generally uses few passwords against many accounts, whereas traditional brute force uses many passwords against one or a small number of accounts.

4. Why can password spraying bypass account-lockout policies?

Because attackers can limit the number of attempts against each individual account, the lockout threshold may never be reached.

5. Can MFA stop password spraying?

MFA can significantly reduce the likelihood that a successfully guessed password results in account takeover. Stronger, phishing-resistant MFA provides better protection against more sophisticated identity attacks.

6. Are long passwords resistant to brute force?

Generally, yes. Increasing password length and randomness greatly increases the number of possible combinations an attacker must consider. Unique, randomly generated passwords are preferable to predictable human-created patterns.

7. Is password spraying the same as credential stuffing?

No. Password spraying tests a small number of likely passwords against many accounts. Credential stuffing uses username/password combinations already obtained from previous breaches.

8. Can Microsoft 365 accounts be targeted by password spraying?

Yes. Any Internet-accessible password authentication system can potentially be targeted. Microsoft 365 environments should use MFA, modern authentication, appropriate access policies, and sign-in monitoring.

9. Can Google Workspace accounts be attacked using password spraying?

Yes. Organizations should use strong authentication controls, MFA or passkeys, administrative protections, and security monitoring to reduce the risk.

10. Can RDP be targeted by brute-force attacks?

Yes. Internet-accessible RDP services can attract automated login attempts. Direct RDP exposure should be avoided where possible in favor of secure gateways, VPNs, MFA, firewall restrictions, or appropriate Zero Trust access solutions.

11. Does changing the RDP port stop brute-force attacks?

Changing a default port may reduce some indiscriminate scanning, but it is not a strong security control. Attackers can scan for services running on non-standard ports. Strong authentication and controlled network exposure are much more important.

12. Should an account automatically lock after several failed attempts?

Lockout can help against rapid attacks, but policies should be designed carefully because overly aggressive lockouts can be abused to deny legitimate users access. Smart or adaptive lockout mechanisms are preferable where available.

13. Can a firewall prevent password spraying?

A firewall can reduce exposure and block certain sources, but it cannot independently determine whether a valid-looking authentication attempt is malicious. Identity controls, MFA, logging, rate limiting, and threat detection are also required.

14. Can CAPTCHA stop brute-force attacks?

CAPTCHA can slow automated attacks against web login interfaces, but it should be considered one layer rather than a replacement for MFA, rate limiting, and strong authentication controls.

15. How can administrators detect password spraying?

Look for authentication failures distributed across many usernames, particularly when they originate from common infrastructure or exhibit similar timing patterns.

16. What should I do if an account successfully logs in during a password-spraying attack?

Treat the account as potentially compromised. Investigate the session, terminate suspicious access, review authentication and audit logs, change affected credentials as appropriate, verify MFA settings, and examine activity performed after authentication.

17. Are administrator accounts more valuable to attackers?

Yes. Administrative accounts can provide elevated access, making them especially important to protect with MFA, separate credentials, limited login locations, and detailed monitoring.

18. Do password managers protect against password spraying?

Password managers help by generating and storing strong, unique passwords. This reduces predictable password selection and password reuse, although password managers should themselves be protected with strong authentication.

19. Are passkeys safer against password attacks?

Passkeys can provide strong resistance to password guessing because there is no reusable password for attackers to spray or brute-force against the service in the traditional way. They also provide strong phishing resistance when correctly implemented.

20. What is the best overall defense against password attacks?

The strongest practical strategy is layered security:

Strong unique credentials + phishing-resistant MFA/passkeys + restricted access + rate limiting/smart lockout + modern authentication + continuous monitoring.

No organization should rely on passwords alone to protect critical systems.

Conclusion

Password spraying and brute-force password attacks pursue the same broad objective—obtaining unauthorized access—but use different strategies.

A traditional brute-force attack concentrates numerous password attempts against a relatively small number of accounts. Password spraying reverses the strategy by attempting a limited number of likely passwords across a large user population.

That difference is important for defenders. Monitoring only repeated failures against individual accounts may identify conventional brute force while overlooking distributed password spraying.

Modern organizations should therefore combine strong unique passwords, MFA or passkeys, smart lockout, rate limiting, conditional access, secure remote access, centralized logging, and identity-threat monitoring.

Most importantly, critical business systems should be designed so that a password by itself is not sufficient to compromise the organization.

#Tags

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