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Password spray attacks are a common brute-force technique where attackers try a few commonly used passwords across many accounts to avoid detection. Microsoft’s solution? Eliminate passwords altogether.
What is Password Spraying?
Password spraying involves testing a small number of weak passwords (e.g., Password123, Welcome1, Winter2024) against many user accounts. Unlike traditional brute-force attacks that target a single account with many passwords, spraying avoids account lockouts and detection.
How Attackers Exploit Workload Identities
Workload identities (service accounts, APIs, cloud functions) are also vulnerable. Attackers use automated tools to spray passwords across these identities, gaining access to cloud resources, databases, and internal systems.
You Should Know: How to Mitigate Password Spraying Attacks
1. Enforce Multi-Factor Authentication (MFA)
MFA blocks 99.9% of automated attacks. Enable it for all users and service accounts.
Azure AD Command:
Set-MsolUser -UserPrincipalName [email protected] -StrongAuthenticationRequirements @{State="Enabled"}
2. Implement Conditional Access Policies
Restrict access based on location, device, and risk level.
Azure AD Policy Example:
New-AzureADMSConditionalAccessPolicy -DisplayName "Block Legacy Auth" -State "Enabled" -Conditions @{ClientAppTypes=@("ExchangeActiveSync","Other")} -GrantControls @{Operator="OR";BuiltInControls=@("Block")}
3. Use Passwordless Authentication
Microsoft recommends Windows Hello, FIDO2 keys, or the Microsoft Authenticator app.
Enable Passwordless Sign-In:
Set-MsolDomainFederationSettings -DomainName yourdomain.com -PreferredAuthenticationProtocol "FIDO2"
4. Monitor & Block Suspicious Activity
Use Azure AD Identity Protection to detect spray attacks.
Check Risky Sign-Ins:
Get-AzureADIdentityRiskEvent -Filter "RiskEventType eq 'passwordSprayAttack'"
5. Disable Legacy Authentication
Attackers exploit protocols like SMTP, IMAP, POP3. Disable them:
PowerShell Command:
Set-CASMailbox -Identity [email protected] -ActiveSyncEnabled $false -ImapEnabled $false -PopEnabled $false
6. Rate Limit & Smart Lockout
Azure AD’s Smart Lockout blocks repeated failed attempts.
Configure Lockout Threshold:
Set-MsolPasswordPolicy -DomainName yourdomain.com -LockoutThreshold 10 -LockoutDuration 00:15:00
What Undercode Say
Password spraying remains a top attack vector because organizations still rely on weak passwords. The best defense is:
– Eliminate passwords (use FIDO2, biometrics).
– Enforce MFA for all accounts.
– Monitor workload identities (service accounts, APIs).
– Block legacy auth (IMAP, POP3, SMTP).
Linux Admins: Protect SSH from Spraying
Install fail2ban sudo apt install fail2ban Configure jail for SSH sudo nano /etc/fail2ban/jail.local Add this rule: [bash] enabled = true maxretry = 3 bantime = 1h
Windows Admins: Audit Failed Logins
Check Event Log for failed logins
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4625} -MaxEvents 50
Expected Output:
- Forbes Microsoft Confirms Password Spraying Attack
- Azure AD Docs: Passwordless Authentication
- Fail2Ban Guide: Protect Linux Servers
References:
Reported By: Pertorbensorensen Microsoft – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
