Microsoft has also been targeted by several password spraying campaigns. One involved an APT (Advanced Persistent Threat) group that managed to compromise internal systems and gain access to source code repositories. Another campaign, conducted via botnets, aimed at Microsoft 365 accounts through secured firewalls.
These incidents illustrate the growing scale and sophistication of this method, which remains a hackers’ go-to tactic. They underscore the urgency for organizations to understand this kind of attack and to implement appropriate defenses.
Guide to Password Spraying Attacks
Password spraying involves testing a handful of common passwords against a vast number of accounts to break into a system. The method is simple to execute. It exploits weak or reused passwords and can be devastatingly effective: a single compromised account can grant access to the entire network.
Password Spraying vs Brute-Force Attacks
Unlike brute-force attacks, which target a single account by trying a very large number of password combinations, password spraying applies a small set of frequently used passwords across multiple accounts. This stealthy approach helps avoid automatic account lockouts, but it is less effective when focused on a single user.
Why is Active Directory a Prime Target for Password Spraying
Microsoft estimates that password spraying attacks are responsible for more than a third of account compromises, underscoring the seriousness of this threat for enterprises. While this method is commonly used against online public services, it is particularly effective against Active Directory (AD). Indeed, even users with minimal privileges can query accounts via LDAP. Moreover, these attempts often evade account lockout policies, making the attack both low-effort and highly impactful.
Given that Active Directory (AD) constitutes a prime target for password spraying, several tools have been specifically designed to target AD environments. For example, CrackMapExec (CME) enables automated, large-scale password-spraying attacks on AD infrastructures. Kerbrute is another widely used tool for discovering and enumerating Active Directory accounts via Kerberos pre-authentication.
Whether cybercriminals use one of these tools or a bespoke utility, their objective remains the same: maintain persistent access to the network and move laterally toward valuable systems and IT assets.
How a Password Spraying Attack Works
A cybercriminal conducts a password spraying attack by following these steps:
- Reconnaissance : the hacker begins by collecting potential usernames, drawing on public directories, account enumeration tools, or databases from the dark web.
- Building a password list : they then assemble a list of easy-to-guess passwords (such as “1234” or “password”), often drawn from publicly leaked databases, because many users reuse weak passwords.
You want to know how many of your end users are currently using weak or compromised passwords? Start a read-only assessment today with Specops Password Auditor. Download the tool for free here.
- Testing phase : the attackers try a few common passwords on many accounts to gauge the password policies in place. They space out attempts to avoid detection or lockouts.
- The attack : if the tests succeed, automated scripts are launched. The goal is to test a large number of accounts while staying discreet.
- Exploitation of the breach : once an account is compromised, attackers can move laterally within the system to access sensitive resources, steal data, or stage other attacks (phishing, malware, etc.).
- Evasion of detection : to avoid being spotted, they may erase logs, use encryption, modify system settings, or plant backdoors to maintain their access.
Key Vulnerabilities
The following vulnerabilities can substantially increase the risk of password spraying attacks in an IT environment:
- Weak password security protocols : low or non-existent lockout thresholds and unlimited login attempts. This leaves environments particularly vulnerable to these attacks.
- Weak or compromised passwords : passwords that are easy to guess or have already been exposed in past breaches.
- High-risk privileged accounts : administrator or service accounts exempt from lockout policies.
- Lack of visibility : insufficient detection capability for account activity due to inadequate monitoring of logins on domain controllers.
Five Preventive Measures
To reduce the risks associated with password spraying, AD administrators should implement the following best practices to strengthen account security and limit exposure:
1. Implement Intelligent Lockout Mechanisms
Intelligent lockouts detect suspicious sign-in attempts while minimizing impact on legitimate users. Unlike fixed lockout policies, they adapt to attack patterns. They use progressively longer lockout periods and variable wait times based on the number of failures.
2. Enable Multi-Factor Authentication
Adding a second factor of authentication (MFA) makes access much harder, even if credentials are compromised. MFA remains one of the most effective defenses against password spraying.
3. Enforce Strict Password Hygiene
Requiring complex passwords and checking whether they have appeared in known breaches significantly reduces risk. Even a strong password can be dangerous if it has already been exposed.
4. Log and Report Suspicious Sign-ins
Centralizing logs via a Security Information and Event Management (SIEM) system enables real-time detection of spikes in failed sign-ins. Early detection allows you to respond before a password spraying attack succeeds.
5. Reduce the Attack Surface
Blocking protocols such as NTLM and restricting RDP access to jump boxes limits entry points and attack surfaces. This not only lowers the opportunities for exploitation but also mitigates the potential impact if a password spraying campaign succeeds.
Strengthen Your Active Directory Security Today
Protecting your AD environment against password spraying requires a comprehensive and proactive approach. Tools such as Specops Password Policy help by enforcing fine-grained policies and continuously scanning your AD against more than 4 billion compromised passwords. Paired with an effective MFA like Specops Secure Access, this delivers multi-layer protection for users, both at the password and authentication levels. Reach out to an expert to bolster your AD security.
