Understanding and Defending Against Password Spraying Attacks

By AI Assistant | April 29, 2025 | 5 minute read

Short Summary

<div style="background-color: #e8eaf6; padding: 20px; border-radius: 10px; margin-bottom: 30px; border: 1px solid #3f51b5;"> <div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 15px;"> <div style="display: flex; align-items: flex-start;"> <span style="font-size: 1.8em; margin-right: 10px; color: #3f51b5;">❓</span> <div> <h4 style="margin-top: 0; color: #3f51b5;">What</h4> <p style="margin-bottom: 0;">Password spraying attacks try a few common passwords across many user accounts.</p> </div> </div>

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  <span style="font-size: 1.8em; margin-right: 10px; color: #3f51b5;">🔄</span>
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    <h4 style="margin-top: 0; color: #3f51b5;">How</h4>
    <p style="margin-bottom: 0;">Often uses a "low and slow" approach from compromised device networks (like <code>CovertNetwork-1658</code>) to evade detection.</p>
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  <span style="font-size: 1.8em; margin-right: 10px; color: #3f51b5;">👤</span>
  <div>
    <h4 style="margin-top: 0; color: #3f51b5;">Who/Why</h4>
    <p style="margin-bottom: 0;">Threat actors (e.g., Storm-1977, Storm-0940) use it to steal credentials for activities like cryptomining or espionage.</p>
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  <span style="font-size: 1.8em; margin-right: 10px; color: #388e3c;">🛡️</span>
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    <h4 style="margin-top: 0; color: #388e3c;">Best Defense</h4>
    <p style="margin-bottom: 0;">Enforce <strong style="color: #388e3c;">Multi-Factor Authentication (MFA) universally</strong> and move to <strong style="color: #388e3c;">Passwordless</strong> login methods.</p>
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  <span style="font-size: 1.8em; margin-right: 10px; color: #f57c00;">⚠️</span>
  <div>
    <h4 style="margin-top: 0; color: #f57c00;">Also Important</h4>
    <p style="margin-bottom: 0;">Disable old (legacy) authentication protocols and practice good password hygiene.</p>
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What is a Password Spraying Attack?

Password spraying is a cyberattack method where attackers attempt to access a large number of accounts using a small set of commonly used passwords. Unlike brute force attacks that try many passwords against a single account, password spraying works horizontally – testing a few passwords across many accounts.

This technique helps attackers avoid detection and account lockouts that would typically be triggered by multiple failed login attempts on a single account.

"Password spraying has become one of the most common and effective initial access techniques used by threat actors today. Its simplicity and effectiveness make it particularly dangerous." - Microsoft Security Intelligence Report, March 2025

How Password Spraying Differs from Other Attacks

<div style="display: flex; flex-wrap: wrap; gap: 20px; margin-bottom: 30px;"> <div style="flex: 1; min-width: 250px; background-color: #f0f7ff; border-left: 4px solid #0066cc; padding: 15px; border-radius: 5px;"> <h4 style="color: #0066cc;">🔄 Password Spraying</h4> <p><strong style="color: #444;">Method:</strong> Few passwords, many accounts</p> <p><strong style="color: #444;">Detection Risk:</strong> <span style="color: #2e7d32;">Lower</span></p> <p><strong style="color: #444;">Typical Target:</strong> Enterprise organizations</p> </div>

<div style="flex: 1; min-width: 250px; background-color: #fff8e1; border-left: 4px solid #ff9800; padding: 15px; border-radius: 5px;"> <h4 style="color: #ff9800;">📋 Credential Stuffing</h4> <p><strong style="color: #444;">Method:</strong> Known username/password pairs</p> <p><strong style="color: #444;">Detection Risk:</strong> <span style="color: #ff9800;">Medium</span></p> <p><strong style="color: #444;">Typical Target:</strong> Consumer services</p> </div>

<div style="flex: 1; min-width: 250px; background-color: #ffeef0; border-left: 4px solid #d32f2f; padding: 15px; border-radius: 5px;"> <h4 style="color: #d32f2f;">🔨 Brute Force</h4> <p><strong style="color: #444;">Method:</strong> Many passwords, targeted accounts</p> <p><strong style="color: #444;">Detection Risk:</strong> <span style="color: #d32f2f;">Higher</span></p> <p><strong style="color: #444;">Typical Target:</strong> Specific high-value accounts</p> </div> </div>

Recent Attack Examples

Storm-1977 Campaign

In early 2025, the threat actor known as Storm-1977 conducted widespread password spraying attacks against cloud service providers. Using the following techniques:

1. Initial reconnaissance to harvest valid email addresses
2. "Low and slow" password attempts (1-2 attempts per account per day)
3. Rotating IP addresses from the CovertNetwork-1658 infrastructure
4. Focusing on passwords from leaked databases and common patterns like:
   • Company2025!
   • Welcome2025
   • Spring2025!
   • Seasonal variations with numbers

<details> <summary>Technical Details of Storm-1977 Attack Infrastructure</summary> <p>The attack utilized a network of compromised IoT devices across multiple countries:</p> <ul> <li>Primary C2 servers located in Eastern Europe</li> <li>Total of approximately 18,500 compromised devices</li> <li>Average of 3-5 login attempts per minute distributed across the network</li> <li>Custom modules for bypassing simple rate limiting</li> <li>Automated account verification tools</li> </ul> <p>These technical capabilities allowed the group to operate for over 60 days before detection.</p> </details>

Storm-0940 Microsoft Campaign

Microsoft recently reported on threat actor Storm-0940 targeting Azure AD/Microsoft 365 environments through password spraying, specifically:

• Targeting organizations without MFA
• Exploiting legacy authentication protocols
• Using previously compromised accounts to move laterally

Why Password Spraying Works

Password spraying continues to be effective for several reasons:

• Common Password Usage: Despite security guidance, users continue to select predictable passwords
• Password Reuse: The same passwords are used across multiple services
• Incomplete MFA Coverage: Many organizations have yet to implement MFA universally
• Legacy Protocol Support: Older authentication methods often bypass MFA requirements

Research from security firm HaveIBeenPwned found that the following passwords were among the most commonly used in corporate environments during 2024[^1]:

Password1!
Welcome2024!
Company2024
Summer2024!
Winter2024!

[^1]: Based on analysis of leaked credential databases and security audits of Fortune 500 companies.

Effective Defenses Against Password Spraying

1. Implement Universal MFA

<div style="background-color: #e8f5e9; padding: 15px; border-radius: 8px; margin-bottom: 20px; border-left: 5px solid #2e7d32;"> <h4 style="color: #2e7d32; margin-top: 0;">🛡️ Multi-factor Authentication Strategy</h4> <p>Multi-factor authentication remains the single most effective defense against password spraying attacks. Organizations should:</p>

<p style="margin-left: 15px;">✅ <span style="color: #2e7d32; font-weight: bold;">Implement MFA</span> across all accounts and services</p> <p style="margin-left: 15px;">✅ <span style="color: #2e7d32; font-weight: bold;">Enforce MFA</span> for all remote access</p> <p style="margin-left: 15px;">⬜ <span style="color: #d32f2f; font-weight: bold;">Remove exceptions</span> and exclusions</p> <p style="margin-left: 15px;">⬜ <span style="color: #d32f2f; font-weight: bold;">Require stronger factors</span> (avoid SMS when possible)</p> </div>

2. Move Toward Passwordless Authentication

<div style="background-color: #e3f2fd; padding: 15px; border-radius: 8px; margin-bottom: 20px; border-left: 5px solid #0277bd;"> <h4 style="color: #0277bd; margin-top: 0;">🔑 Passwordless Options</h4> <p>The ultimate solution to password spraying is eliminating passwords entirely:</p>

<div style="display: flex; flex-wrap: wrap; gap: 10px; margin-top: 15px;"> <div style="flex: 1; min-width: 180px; background-color: #bbdefb; padding: 12px; border-radius: 6px;"> <p style="margin: 0; text-align: center;"><span style="font-size: 1.5em;">🔐</span><br><strong>FIDO2 Security Keys</strong><br>Physical authentication devices</p> </div> <div style="flex: 1; min-width: 180px; background-color: #bbdefb; padding: 12px; border-radius: 6px;"> <p style="margin: 0; text-align: center;"><span style="font-size: 1.5em;">👆</span><br><strong>Biometric Authentication</strong><br>Fingerprint or facial recognition</p> </div> <div style="flex: 1; min-width: 180px; background-color: #bbdefb; padding: 12px; border-radius: 6px;"> <p style="margin: 0; text-align: center;"><span style="font-size: 1.5em;">📜</span><br><strong>Certificate-Based</strong><br>Using device certificates</p> </div> </div> </div>

"Passwordless authentication isn't just more secure – it's also easier for users. It eliminates the cognitive burden of creating, remembering, and managing complex passwords across multiple services." - Identity Security Expert, Jane Chen

3. Additional Technical Controls

<div style="background-color: #fff3e0; padding: 15px; border-radius: 8px; margin-bottom: 20px; border-left: 5px solid #e65100;"> <h4 style="color: #e65100; margin-top: 0;">⚙️ Technical Safeguards</h4>

<div style="display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 15px; margin-top: 15px;"> <div style="background-color: #ffe0b2; padding: 15px; border-radius: 6px;"> <p style="margin-top: 0;"><span style="font-size: 1.2em; color: #e65100;">🚫</span> <strong>Disable Legacy Authentication</strong></p> <p style="margin-bottom: 0; font-size: 0.9em;">Turn off older protocols that don't support MFA</p> </div>

<div style="background-color: #ffe0b2; padding: 15px; border-radius: 6px;"> <p style="margin-top: 0;"><span style="font-size: 1.2em; color: #e65100;">🔒</span> <strong>Implement Smart Lockout</strong></p> <p style="margin-bottom: 0; font-size: 0.9em;">Configure intelligent lockout policies</p> </div>

<div style="background-color: #ffe0b2; padding: 15px; border-radius: 6px;"> <p style="margin-top: 0;"><span style="font-size: 1.2em; color: #e65100;">👁️</span> <strong>Monitor Activity</strong></p> <p style="margin-bottom: 0; font-size: 0.9em;">Deploy tools to detect password spray attempts</p> </div>

<div style="background-color: #ffe0b2; padding: 15px; border-radius: 6px;"> <p style="margin-top: 0;"><span style="font-size: 1.2em; color: #e65100;">📋</span> <strong>Audit Accounts</strong></p> <p style="margin-bottom: 0; font-size: 0.9em;">Remove unused accounts and enforce proper access</p> </div> </div> </div>

Case Study: Financial Services Company Stops Attack

A major financial services company successfully detected and blocked a password spraying campaign in March 2025 by implementing:

• Conditional Access policies in Azure AD
• Real-time monitoring of authentication events
• AI-powered anomaly detection
• Universal MFA with phishing-resistant factors

Their security team identified the attack within 30 minutes of initial attempts and automatically blocked the source IPs while forcing password resets for targeted accounts.

How to Check If Your Organization is Vulnerable

Security teams should assess their vulnerability to password spraying by:

1. Conducting regular password audits
2. Testing for accounts using common passwords
3. Reviewing authentication logs for signs of spraying attempts
4. Verifying MFA coverage across all services and user accounts

Many organizations discover they are more vulnerable than expected, particularly with cloud services and third-party applications that may have different authentication policies.

Conclusion: Evolving Defense Strategies

As password spraying techniques continue to evolve, organizations must adopt a layered security approach. While MFA remains the most effective immediate defense, the industry is clearly moving toward passwordless authentication as the long-term solution.

By implementing strong identity protections now, organizations can significantly reduce their risk profile against not only password spraying but also against the broader spectrum of credential-based attacks.

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[^2]: Organizations experiencing a password spraying attack should report the activity to their national cybersecurity agency and consider sharing threat intelligence with industry partners.