What Is Password Spraying?

Password spraying attacks involve trying several common passwords across many different accounts. For example, an attacker might try ‘password’, ‘123456’, and similar common passwords across every known account within an organization. Common targets include remote access tools (VPN, RDP, etc.), corporate email (M365, Google Workspace), and other publicly-accessible login portals.

This tactic is designed to evade defenses that look for a large number of failed login attempts before locking down an account. If successful, the attacker can leverage the unauthorized access to access sensitive data, plant malware, or expand their foothold on the organization’s systems.

Key Highlights

• Password spraying tries a few likely passwords across many usernames.
• The tactic is designed to avoid lockouts and evade simple per-account detection.
• Common targets include Active Directory, cloud identity platforms, Microsoft 365, VPNs, and other remote access services.
• Repeated low-volume authentication failures across many accounts are a core detection signal.
• Strong password policy, MFA, and centralized authentication monitoring can reduce exposure, but no single control eliminates risk.

How Does Password Spraying Work?

Password spraying involves an attacker working down a list of known usernames, trying a list of common passwords for each. Often, they try one password at a time across all accounts to avoid multiple failed login attempts for a particular account within a short period of time. This type of attack works because the use of common, reused passwords is widespread.

Attackers Collect Usernames and Accounts

Password spraying attacks take advantage of the fact that many enterprises have standardized naming conventions, such as first-initial-last-name. Attackers could guess common conventions or use a single known email address to extrapolate usernames.

A list of employee names can be collected from publicly available sources. For example, company websites, LinkedIn profiles, and other pages can provide a partial list of employees, which is enough for this type of attack.

Attackers Try Common Passwords

Unless they’re using a password manager, employees need to be able to remember their passwords, and weak, common passwords are easier to remember. Common examples include seasonal passwords (Spring26), organization-themed ones, and similar choices.

These types of attacks take advantage of the probability that people will select a weak, predictable password. If an organization doesn’t implement and enforce strong password policies, just a few guesses per account is often enough to gain access.

How Password Spraying Is Different from Brute Force and Credential Stuffing

Brute force attacks include a few different techniques, including password spraying and credential stuffing. Password spraying differs from a traditional brute force attack in that it uses a few passwords for many usernames rather than a lot of different passwords for a particular account.

Credential stuffing uses passwords that have been exposed in breaches, looking for reused passwords across multiple accounts. Password spraying tests weak passwords, looking for the use of common passwords for a corporate account.

What Makes Password Spraying Harder to Catch?

Traditional brute force and credential stuffing attacks try to crack a particular account, creating a large number of failed login attempts for that account. In contrast, password spraying only introduces a few failed login attempts for each account it targets.

This makes password spraying more difficult to detect than these other attacks. A few failed logins could be attributed to users mistyping their passwords, especially if they’re spread out over time, and an organization is looking at a single account in isolation.

Common Targets of Password Spraying

Password spraying attacks commonly target publicly-accessible login portals that serve large numbers of users. Common examples include:

• Remote access tools (VPNs, RDP, etc.)
• Identity providers
• Active Directory environments

Since this attack is used for initial access, the attacker needs login portals that are publicly accessible. Large user populations also increase the probability of success since an attacker is trying only a few passwords per target.

Active Directory Environments

Many organizations use Active Directory (AD) for identity management, meaning that they contain many valid enterprise accounts. Attackers can use AD-connected services and Kerberos-based workflows as the targets for their password spraying attacks.

Since AD centralizes identity management, a single breached password provides broad access to corporate systems and applications. From there, attackers can remotely access systems and attempt to elevate their privileges or move laterally through the network.

VPN and Remote Access Portals

VPNs and other remote access portals are designed to allow an employee remote access to a corporate environment. If an attacker can guess an employee’s password, they enjoy the same level of access.

Even if unsuccessful, password spraying attacks can have significant business impacts. They introduce noise into authentication logs, cause user lockouts, and put additional strain on security teams.

Signals That Help Detect Password Spraying

Password spraying can be detected using data sources that record failed login attempts for corporate accounts. These could include logs and alerts from corporate identity and access management (IAM) systems and remote access solutions like VPNs and RDP.

Identifying attacks requires correlating data and identifying patterns across multiple user accounts, since a particular account may only show a few failed login attempts. Warning signs involve multiple failed logins by different accounts that are clustered in time, potentially originating from distributed and unusual sources.

Suspicious Authentication Activity

Password spraying attacks generate a large number of failed login attempts for every success. These attempts will likely have similar timing, source infrastructure, and user-agent patterns.

Multiple Failures Per Account

For this type of attack, a few failures per account are more suspicious than a large number of failures on a particular account. This is because attackers only try a few passwords per account rather than trying to brute force a particular one. Security teams should correlate data across multiple accounts to identify attacks that might not trigger a threshold for any one of them.

Security Controls That Reduce Password Spraying Risk

Password spraying attacks take advantage of user accounts that are solely reliant on weak passwords for authentication. Ways organizations can mitigate this risk include:

• Strong password policies and enforcement
• Multi-factor authentication (MFA)
• Hardening of exposed authentication services
• Monitoring and alerting of unusual login activity

Strong Password Policies 

Password sprayers try to identify and access accounts with weak, common passwords. Strong password policies reduce the viability of this attack by moving employees away from these easily-guessable passwords. However, these policies are only useful if they’re enforced, not just a document with password guidelines.

Multi-factor Authentication (MFA)

Password sprayers rely on the fact that a compromised password is enough to gain access to an account. MFA increases the difficulty of this attack by forcing the attacker to also steal valid MFA codes for each attempt and subsequent use of the account. While MFA doesn’t eliminate the threat, it makes the attack much more difficult to perform.

Secure Configurations and Monitoring 

Public-facing authentication services are a common target for password spraying because anyone can test passwords on these services. Implementing secure configurations and monitoring helps to reduce the threat by flagging or blocking repeated failed logins that are a hallmark of this attack technique.

Why Password Spraying Still Works

Password spraying still works because people commonly choose weak or predictable passwords to help them remember how to log into their accounts. Since enterprises have large numbers of accounts with predictable usernames, attackers can take advantage of the fact that at least one account is likely secured with a weak password. Public-facing authentication portals give attackers the opportunity to test potential passwords, and incomplete visibility reduces the risk that organizations will identify these distributed attacks before it’s too late.

Why Password Spraying Matters for Identity Security

Password spraying is a brute-force attack designed to evade thresholds and other methods of identifying password-guessing attacks based on repeated login failures. As long as weak passwords are common and trusted to secure enterprise accounts, this attack will continue to work.

Organizations need broad visibility into authentication and an understanding of common attack vectors and patterns. Additionally, companies need strong authentication security, such as MFA and strong password policies or passwordless login.

FAQ

What is password spraying in simple terms?

Password spraying tries a few common passwords across many different user accounts. This attack maximizes the probability that at least one account will have a guessable password and evades threshold-based methods of detecting password-guessing attacks.

Is password spraying a type of brute-force attack?

Yes, password spraying is a particular type of brute-force password guessing attack. However, instead of trying many passwords for a particular account, it tries a few different passwords across many different accounts.

How is password spraying different from credential stuffing?

Password spraying tries a few common passwords across many different accounts, targeting weak password usage. Credential stuffing uses username/password pairs from password breaches to take advantage of credential reuse.

Can MFA stop password spraying?

MFA reduces the risk of password spraying since it forces attackers to steal an additional authentication factor to guess passwords and access compromised accounts. However, it’s not perfect since many common forms of MFA can be defeated, making monitoring and response still important for authentication security.

What should teams monitor for password spraying?

Password spraying detection requires monitoring and correlating unusual login activity across many accounts. These attacks will cause a spike in overall failed logins, with a few failed attempts for each of many accounts.