Quick answer: Password spraying is an attack based on trying a single common password (for example "Password2026") across many different user accounts. It works the opposite way to classic brute force: instead of many passwords against one account, it tries one password against many accounts. This avoids account lockout and quietly searches a large user base for a weak password. The foundation of defense is multi factor authentication, a strong password policy and login anomaly monitoring.

How does password spraying differ from brute force?

A classic brute force attack tries thousands of passwords against a single account. On most systems this triggers the account lockout mechanism and is noticed quickly. Password spraying reverses this problem.

The attacker takes a single common password and tries it against hundreds or thousands of different accounts. Because only one attempt is made per account, lockout is not triggered. The logic is this: if an organization has hundreds of users, at least a few of them are bound to use a weak and predictable password.

Feature Brute force Password spraying Credential stuffing
Approach Many passwords per account One password per many accounts Leaked password-account pairs
Lockout risk High Low Low
Source Password list Common passwords Data breach dumps

Why is it so effective?

Password spraying is effective because it targets human behavior. In an organization, seasonal and predictable passwords (company name, year, "Password123") are surprisingly common. All the attacker needs is a list of valid usernames and a few common password guesses. Usernames are also often easily obtained from the email format or open sources.

This attack is especially dangerous on exposed authentication endpoints (webmail, VPN, single sign on portals), because these are reachable from the internet and a single weak account becomes a door into the organization.

Defense

  1. Enforce multi factor authentication (MFA) on all exposed authentication endpoints, this is the single most effective measure.
  2. Ban common and predictable passwords (use password block lists).
  3. Monitor login anomalies by source and time rather than per account (the pattern of one attempt across many accounts in a short time).
  4. Where possible, restrict exposed identity endpoints by geography and IP.
  5. Catch known weak passwords with leaked credential detection.

The KAOS and DSET approach

DSET tests organizations' exposed authentication surface in an authorized way and measures resilience against password based attacks including password spraying. The problem we most often see in the field is multi factor authentication disabled on an exposed portal and the prevalence of seasonal passwords. Our KAOS security engine evaluates this attack in an evidence based way without causing lockouts. Our goal is not fear but showing the real path to a weak account and the priority for closing it.

Related reading: leaked passwords and credential stuffing, password, 2FA and passkey security, modern password policy NIST, IAM identity and access management, ITDR identity threat detection, SIEM and SOC.

Frequently asked questions

Are password spraying and credential stuffing the same? No. Password spraying tries guessed common passwords across many accounts. Credential stuffing tries real password-account pairs leaked from a data breach. Both avoid account lockout, but the source is different: one is guessing, the other is leaked data. The most effective measure against both is multi factor authentication.

Does account lockout stop this attack? It is not enough on its own. Password spraying is designed precisely to avoid account lockout: it makes only one attempt per account, so the lockout threshold is not triggered. That is why, instead of lockout, you need source and time based monitoring that catches the pattern of one attempt across many accounts in a short time.

What is the most effective defense? Multi factor authentication (MFA). Even if the attacker guesses an account's password correctly, they cannot log in without the second factor. That is why enforcing MFA, especially on exposed endpoints such as webmail, VPN and single sign on, is the strongest defense against password spraying. It should be combined with a strong password policy and anomaly monitoring.

Sources

To test the resilience of your exposed authentication surface against password attacks, you can talk to our team at Ankara Hacettepe Technopark. Contact DSET.