Cybersecurity
What Is Password Spraying?
Password spraying is a stealthy brute-force attack that uses common passwords across many accounts to bypass lockout policies. Learn how it works and how to defend against it.
Password spraying is a type of cyberattack that uses weak passwords to get into multiple user accounts without permission. Using the same password or a list of commonly used passwords on multiple accounts is what this method is all about. The goal is to get around common security measures like account lockouts.
Attacks that use password spraying are very effective because they target the weakest link in cybersecurity: people and how they manage their passwords.
What Is Password Spraying and How Does It Work?
A brute-force attack called password spraying tries to get into multiple accounts with the same password. Attackers can avoid account shutdown policies with this method. These policies are usually put in place to stop brute-force attacks that try to access a single account with multiple passwords. For password spraying to work, a lot of people need to use weak passwords that are easy to figure out.
Attackers often get lists of usernames from public directories or data leaks that have already happened. They then use the same passwords to try to log in to all of these accounts. The process is automated so that it can try a handful of common passwords against every account on the list, spacing out the attempts to stay under lockout thresholds.
The attackers pick a small group of common passwords that at least some people in the target company are likely to use. These passwords are usually taken from lists of common passwords available to the public, or they are based on information about the organization, like the name or location of the company.
Attackers lower their chances of being locked out while increasing their chances of successfully logging in by using the same set of passwords for multiple accounts.
A lot of people do not notice password spraying attacks because they do not cause as much suspicious behavior as other types of brute-force attacks. The attack looks less dangerous because only one password is used at a time, so it might not set off any instant alarms. But if these attempts are made on multiple accounts, they can have a terrible effect if not properly tracked and dealt with.
How Does Password Spraying Differ from Other Cyberattacks?
Password spraying is distinct from other brute-force attacks in its approach and execution. While traditional brute-force attacks focus on trying multiple passwords against a single account, password spraying uses a single password across multiple accounts. This difference allows attackers to avoid triggering account lockout policies, which are designed to protect against excessive login attempts on a single account.
Brute-force attacks involve systematically trying all possible combinations of passwords to gain access to an account. These attacks are often resource-intensive and can be easily detected due to the high volume of login attempts on a single account.
Credential stuffing is another type of attack that involves using lists of stolen username and password combinations to attempt logins. Unlike password spraying, credential stuffing relies on previously compromised credentials rather than guessing common passwords.
Password spraying attacks are stealthier than traditional brute-force attacks because they distribute attempts across many accounts, making them harder to detect. This stealthiness is a key factor in their effectiveness, as they can often go unnoticed until significant damage has been done.
How Can Organizations Detect and Prevent Password Spraying Attacks?
Detecting password spraying attacks requires a proactive approach to monitoring and analysis. Organizations must implement robust security measures to identify suspicious activities early. This includes monitoring for unusual login attempts, establishing baseline thresholds for failed logins, and using advanced security tools to detect patterns indicative of password spraying.
Implementing Strong Password Policies: Password spraying only works when someone picks a common password, so the most effective policy blocks those passwords outright. NIST's current guidelines, SP 800-63B-4, call for long passwords (at least 15 characters when a password is the only sign-in factor), checking every new password against a list of common and breached passwords, and dropping both forced complexity rules and routine password expiration. Passwords should be changed when there is evidence they were compromised. Tools like password managers can help users generate and securely store long, unique passwords.
Blocking Common Passwords: In Microsoft 365, Microsoft Entra Password Protection blocks known weak passwords and their common variations automatically, and you can add your own company-specific terms, such as your business name and city, to a custom banned list. The custom list requires Microsoft Entra ID P1, which is included in Microsoft 365 Business Premium.
Deploying Multi-Factor Authentication: MFA significantly reduces the risk of unauthorized access by requiring additional verification steps beyond just a password. Implementing MFA across all user accounts, especially those accessing sensitive information, is essential. Also block legacy authentication protocols, such as older email sign-in methods that cannot prompt for MFA, because attackers often aim password spraying at them. In Microsoft 365, security defaults or Conditional Access policies can block them.
Conducting Regular Security Audits: Regular audits of authentication logs and security posture assessments can help identify vulnerabilities that could facilitate password spraying attacks. These audits should focus on detecting trends that automated tools might miss.
Additional Measures to Enhance Security
Organizations should set up detection systems for login attempts to multiple accounts from a single host over a short period. This can be a clear indicator of a password spraying attempt. Lockout policies that balance security with usability also help. Microsoft Entra smart lockout, which is on by default for Microsoft 365 accounts, temporarily locks out sign-in attempts after repeated failures while trying to tell a real user apart from an attacker.
User education plays a vital role in preventing password spraying attacks. Users should be informed about the risks of weak passwords and the importance of MFA. Regular training sessions can help reinforce best practices in password management and security awareness.
Having a comprehensive incident response plan in place is essential for quickly responding to and mitigating the effects of a password spraying attack. This plan should include procedures for alerting users, changing passwords, and conducting thorough security audits.
Password spraying is a significant threat to cybersecurity that exploits weak passwords to gain unauthorized access to multiple accounts. Organizations must prioritize strong password policies, multi-factor authentication, and proactive monitoring to protect against these attacks.
Cyber One Solutions helps businesses set up these defenses in Microsoft 365, including banned password lists, MFA, legacy authentication blocking, and sign-in monitoring. Contact us today to review how your accounts are protected against password spraying.