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Updated on October 24, 2025
Password spraying is a type of cyberattack in which an attacker attempts to gain unauthorized access to a system by trying a small number of common passwords against a large list of usernames. Unlike a brute-force attack, which targets a single account with many passwords, password spraying is designed to avoid account lockouts. This technique bypasses common security controls that are triggered after a few failed login attempts. This attack is highly effective for compromising organizations that have a large user base with weak password policies.
Definition and Core Concepts
Password spraying is an authentication attack that distributes a limited set of credentials across multiple user accounts to avoid detection. The attacker’s goal is to find at least one valid username-password combination to gain a foothold in the network. The attack is most effective when targeting systems with many users and when the passwords being tested are known to be common, such as Summer2025!, Password123, or the name of the company.
Foundational concepts:
- Brute-Force Attack: This attack tries all possible password combinations against a single user account. It is easily detected and blocked by account lockouts.
- Account Lockout: This is a security feature that locks an account after a certain number of failed login attempts. Password spraying is designed to bypass this feature.
- Service Accounts: These accounts are often prime targets for password spraying. They are rarely monitored for failed logins and often have a common password policy.
- Lateral Movement: This is the technique an attacker uses to move from a compromised system to other systems on the network. A successful password spray attack is often the first step in this process.
How It Works
A password spraying attack is a methodical, automated process that can be performed with various tools. The process unfolds in several distinct steps.
Reconnaissance
An attacker first gathers a list of valid usernames for a target organization. This can be done through open-source intelligence (OSINT), such as social media, or by using tools to enumerate user accounts on a public-facing service like a login page or an email server.
Password List Creation
The attacker creates a small list of common passwords to test. The list is usually limited to between five and ten passwords to stay under the typical account lockout threshold.
Authentication Attempts
The attacker’s tool iterates through the username list, trying the first password against every single account. For example, it will try Summer2025! against user1, user2, user3, and so on.
Repeat
After the first password has been tested against all accounts, the tool moves on to the next password on the list, such as Password123. It then repeats the process for every user.
Success
If the attacker finds a valid combination, like user15:Password123, they have a foothold in the network. At this point, they can begin the next phase of the attack.
Key Features and Components
- Low-and-Slow: The attack is designed to be slow to avoid detection. By spreading attempts over a long period, it can bypass simple login failure thresholds.
- Effectiveness: The attack is highly effective against organizations that do not enforce strong password policies or use multi-factor authentication (MFA).
- Automation: Password spraying is almost always performed with automated tools or scripts.
Use Cases and Applications
Password spraying is a common technique attackers use to gain initial access to a network. Its applications are varied but typically fall into a few key areas.
Initial Access
A successful password spray provides an attacker with a valid username and password. This credential can be used to log in to email accounts, virtual private networks (VPNs), or cloud services.
Lateral Movement
Once an attacker has a valid credential, they can use it to move to other systems on the network. From there, they can work to escalate their privileges.
Cloud Environments
Password spraying is a particularly effective attack against cloud services. Many of these services have a single, public-facing login page, which makes them a clear target.
Advantages and Trade-offs
Advantages
This attack is highly effective against organizations with weak password policies. It is also difficult to detect with simple login failure thresholds.
Trade-offs
The attack requires a valid list of usernames. The attacker must also be careful to not exceed the account lockout threshold.
Troubleshooting and Considerations
Multi-Factor Authentication (MFA)
MFA is the most effective defense against password spraying. Even if an attacker finds a valid password, they will be unable to log in without the second factor.
Strong Password Policies
Enforcing a strong password policy, such as requiring a minimum of 14 characters, can make it much more difficult for attackers to guess passwords.
Account Lockout Thresholds
While password spraying is designed to bypass them, an administrator should still have a low account lockout threshold. This measure helps prevent standard brute-force attacks.
Monitoring and Logging
Monitoring login attempts for anomalous behavior can help detect this type of attack. Look for a large number of failed logins originating from a single IP address over a short period.
Conditional Access Policies
Implementing conditional access policies can help mitigate the risk of password spraying. These policies can restrict logins from unusual locations or at unusual times.
Key Terms Appendix
- Brute-Force Attack: An attack that tries all possible password combinations.
- Multi-Factor Authentication (MFA): A security process that requires a user to provide two or more verification factors to gain access to a resource.
- Lateral Movement: The technique of moving from one system to another within a network.
- OSINT: Open-Source Intelligence, the process of collecting information from public sources.
- Account Lockout: A security feature that locks an account after too many failed login attempts.
