Windows Event ID 4776 – Microsoft-Windows-Security-Auditing: Computer Account Authentication

Start by examining the specific details of Event ID 4776 to understand the authentication context and identify potential issues.

1. Open Event Viewer on the domain controller where the event occurred
2. Navigate to Windows Logs → Security
3. Filter for Event ID 4776 using the filter option or search functionality
4. Double-click the event to view detailed information including:
   • Computer Account Name
   • Source Workstation
   • Authentication Package
   • Status Code
   • Substatus Code
5. Check the Status Code field for authentication results:
   • 0x0 = Success
   • 0xC0000064 = User name does not exist
   • 0xC000006A = User name is correct but password is wrong
   • 0xC0000234 = User account locked out

Use PowerShell to efficiently query and analyze Event ID 4776 across multiple domain controllers or time periods.

1. Open PowerShell as Administrator on a domain controller or management workstation
2. Query recent computer authentication events:

   Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4776} -MaxEvents 50 | Select-Object TimeCreated, Id, LevelDisplayName, Message

3. Filter for failed authentication attempts:

   Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4776} | Where-Object {$_.Message -like '*0xC000*'} | Select-Object TimeCreated, Message

4. Search for specific computer account authentication:

   Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4776} | Where-Object {$_.Message -like '*COMPUTERNAME$*'} | Format-Table TimeCreated, Message -Wrap

5. Export results for analysis:

   Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4776; StartTime=(Get-Date).AddDays(-7)} | Export-Csv -Path C:\Temp\Computer_Auth_Events.csv -NoTypeInformation

When Event ID 4776 shows authentication failures, investigate the computer account status and configuration in Active Directory.

1. Open Active Directory Users and Computers on a domain controller
2. Navigate to the Computers container or search for the specific computer account
3. Right-click the computer account and select Properties
4. Check the Account tab for:
   • Account disabled status
   • Account lockout status
   • Password last set date
5. Verify computer account password using PowerShell:

   Get-ADComputer -Identity "COMPUTERNAME" -Properties PasswordLastSet, Enabled, LockedOut | Select-Object Name, PasswordLastSet, Enabled, LockedOut

6. Reset computer account password if necessary:

   Reset-ComputerMachinePassword -Server DC01.domain.com

7. Check for duplicate computer accounts:

   Get-ADComputer -Filter "Name -eq 'COMPUTERNAME'" | Select-Object Name, DistinguishedName

Perform advanced analysis of Event ID 4776 patterns to identify security issues or authentication problems across the domain.

1. Create a comprehensive query to analyze authentication patterns:

   $Events = Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4776; StartTime=(Get-Date).AddDays(-30)}
   $Analysis = $Events | ForEach-Object {
       $Message = $_.Message
       $Computer = ($Message | Select-String 'Account Name:\s+(.+?)\$').Matches[0].Groups[1].Value
       $Source = ($Message | Select-String 'Source Workstation:\s+(.+)').Matches[0].Groups[1].Value
       $Status = ($Message | Select-String 'Error Code:\s+(0x[0-9A-F]+)').Matches[0].Groups[1].Value
       [PSCustomObject]@{
           TimeCreated = $_.TimeCreated
           Computer = $Computer
           Source = $Source
           Status = $Status
           Success = $Status -eq '0x0'
       }
   }
   $Analysis | Group-Object Computer | Sort-Object Count -Descending

2. Identify computers with high failure rates:

   $FailureAnalysis = $Analysis | Where-Object {-not $_.Success} | Group-Object Computer | Where-Object {$_.Count -gt 10} | Sort-Object Count -Descending
   $FailureAnalysis | Select-Object Name, Count

3. Check for authentication attempts from unexpected sources:

   $Analysis | Where-Object {$_.Source -ne $_.Computer -and $_.Source -ne ''} | Group-Object Source | Sort-Object Count -Descending

4. Correlate with other security events for comprehensive analysis:

   Get-WinEvent -FilterHashtable @{LogName='Security'; Id=@(4776,4768,4769); StartTime=(Get-Date).AddHours(-1)} | Sort-Object TimeCreated

Implement comprehensive monitoring solutions for Event ID 4776 to proactively detect authentication issues and security threats.

1. Configure Windows Event Forwarding to centralize computer authentication logs:

   wecutil cs subscription.xml

   Where subscription.xml contains Event ID 4776 collection rules
2. Create custom PowerShell monitoring script:

   # Save as Monitor-ComputerAuth.ps1
   $LastCheck = (Get-Date).AddMinutes(-5)
   $FailedEvents = Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4776; StartTime=$LastCheck} | Where-Object {$_.Message -like '*0xC000*'}
   if ($FailedEvents.Count -gt 5) {
       Send-MailMessage -To "admin@company.com" -From "monitoring@company.com" -Subject "High Computer Authentication Failures" -Body "$($FailedEvents.Count) failed computer authentications detected" -SmtpServer "mail.company.com"
   }

3. Schedule the monitoring script using Task Scheduler:

   $Action = New-ScheduledTaskAction -Execute "PowerShell.exe" -Argument "-File C:\Scripts\Monitor-ComputerAuth.ps1"
   $Trigger = New-ScheduledTaskTrigger -RepetitionInterval (New-TimeSpan -Minutes 5) -RepetitionDuration (New-TimeSpan -Days 365) -At (Get-Date)
   Register-ScheduledTask -TaskName "ComputerAuthMonitoring" -Action $Action -Trigger $Trigger -RunLevel Highest

4. Configure audit policy to ensure Event ID 4776 logging:

   auditpol /set /subcategory:"Credential Validation" /success:enable /failure:enable

5. Implement log retention policy in Group Policy:
   • Navigate to Computer Configuration → Policies → Windows Settings → Security Settings → Event Log
   • Configure Security log maximum size and retention settings