What is Password Spraying? The Dreaded Cyberattack Causing Massive Damage

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Password spraying is a cyberattack technique where attackers try a small number of commonly used passwords across many user accounts instead of brute-forcing a single account. Unlike traditional brute-force attacks, this method avoids account lockouts while increasing the chances of unauthorized access.

🔗 Reference: phonandroid.com

You Should Know: How to Defend Against Password Spraying

1. Detect Password Spraying Attempts

Monitor authentication logs for multiple failed login attempts across different accounts using the same password.

Linux Command to Check Auth Logs:

grep "Failed password" /var/log/auth.log

Windows Command (PowerShell) to Check Security Logs:

Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4625} | Format-Table -AutoSize

2. Enforce Strong Password Policies

  • Require long, complex passwords (12+ characters, mix of letters, numbers, symbols).
  • Block common passwords (e.g., “Password123”, “Welcome1”).

Linux (PAM) Password Policy Enforcement:

Edit `/etc/pam.d/common-password`:

password requisite pam_pwquality.so retry=3 minlen=12 difok=3 ucredit=-1 lcredit=-1 dcredit=-1 ocredit=-1 enforce_for_root

Windows Group Policy for Password Complexity:

1. Open `gpedit.msc`

2. Navigate to:

Computer Configuration → Windows Settings → Security Settings → Account Policies → Password Policy

3. Enable:

  • Minimum password length = 12
  • Password must meet complexity requirements = Enabled

3. Implement Multi-Factor Authentication (MFA)

MFA significantly reduces the risk of password spraying by requiring a second verification step.

Linux (Google Authenticator Setup):

sudo apt install libpam-google-authenticator 
google-authenticator

Edit `/etc/pam.d/sshd`:

auth required pam_google_authenticator.so

Windows MFA via Azure AD:

Connect-MsolService 
Set-MsolUser -UserPrincipalName [email protected] -StrongAuthenticationRequirements @{State="Enabled"}

4. Rate Limiting & Account Lockout Policies

Prevent rapid login attempts by enforcing delays or temporary lockouts.

Linux (Fail2Ban Setup):

sudo apt install fail2ban 
sudo systemctl enable fail2ban

Edit `/etc/fail2ban/jail.local`:

[bash] 
enabled = true 
maxretry = 3 
bantime = 3600

Windows Account Lockout Policy:

1. Open `gpedit.msc`

2. Navigate to:

Computer Configuration → Windows Settings → Security Settings → Account Policies → Account Lockout Policy

3. Set:

  • Account lockout threshold = 5 invalid attempts
  • Lockout duration = 30 minutes

5. Monitor & Block Suspicious IPs

Use firewalls or intrusion detection systems (IDS) to block repeated login attempts.

Linux (IPTables Rule to Block Brute-Force IPs):

iptables -A INPUT -p tcp --dport 22 -m recent --name sshbf --set 
iptables -A INPUT -p tcp --dport 22 -m recent --name sshbf --rcheck --seconds 60 --hitcount 5 -j DROP

Windows (Firewall Rule via PowerShell):

New-NetFirewallRule -DisplayName "Block Brute-Force IPs" -Direction Inbound -Action Block -RemoteAddress 192.168.1.100

What Undercode Say

Password spraying remains a severe threat due to weak password habits. Organizations must:
– Enforce MFA everywhere.
– Monitor authentication logs (grep "Failed password" /var/log/auth.log).
– Block common passwords (pam_pwquality on Linux, GPO on Windows).
– Use rate limiting (fail2ban on Linux, lockout policies on Windows).
– Educate users on password hygiene.

Expected Output:

✅ Stronger authentication logs monitoring

✅ Reduced account takeover risks

✅ Blocked brute-force attempts

✅ Compliance with security best practices

For further reading: OWASP Password Spraying Mitigation

References:

Reported By: Piveteau Pierre – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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