Private/ActiveDirectory/Test-ValidDistinguishedName.ps1
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#Requires -Version 5.1 <# .SYNOPSIS Distinguished Name validation module for Active Directory operations .DESCRIPTION Provides comprehensive validation of Active Directory Distinguished Names with security filtering, format validation, and LDAP compliance checking. Focused solely on DN validation and security protection. .NOTES Author: Jeffrey Stuhr Blog: https://www.techbyjeff.net LinkedIn: https://www.linkedin.com/in/jeffrey-stuhr-034214aa/ Last Updated: 2025-07-04 Version: 2.0.0 TROUBLESHOOTING: - For DN validation issues: .\Troubleshooting\Security\DN-Validation.md - For AD object access: .\Troubleshooting\Common\AD-Access-Issues.md #> function Test-ValidDistinguishedName { <# .SYNOPSIS Validates Distinguished Name format with comprehensive security checks .DESCRIPTION Performs comprehensive validation of Active Directory Distinguished Names including format validation, length checks, and security character filtering to prevent injection attacks and ensure proper AD object referencing. BUSINESS VALUE: - Prevents security vulnerabilities through malformed DN injection - Ensures data integrity in Active Directory operations - Provides consistent validation across all AD interactions - Supports compliance requirements for access control validation - Enables secure automation of AD management tasks SECURITY FEATURES: - Injection attack prevention through character filtering - Buffer overflow protection via length validation - Component structure validation for proper LDAP format - Domain component verification for valid AD context - Comprehensive logging for security audit requirements .PARAMETER DistinguishedName [String] (Mandatory) The Distinguished Name string to validate. Accepts pipeline input for batch validation operations. VALIDATION RULES: - Maximum length: 1024 characters (LDAP standard) - Must contain at least one domain component (DC=) - Components must follow CN=, OU=, or DC= format - No dangerous characters allowed (<>:"/\|?*\x00-\x1f\x7f-\x9f) - Each component must have non-empty value after equals sign SECURITY CONTEXT: Input validation is critical for preventing LDAP injection attacks and ensuring proper Active Directory object identification. .PARAMETER CorrelationId [String] (Optional) Correlation ID for tracking validation requests. Auto-generated if not provided for audit trail purposes. .OUTPUTS [Bool] Returns $true if DN is valid and secure, $false otherwise. All validation failures are logged with appropriate detail level. .EXAMPLE PS> Test-ValidDistinguishedName -DistinguishedName "OU=Users,DC=contoso,DC=com" DESCRIPTION: Validates a standard organizational unit DN OUTPUT: $true for valid DN format USE CASE: Parameter validation for AD operations SECURITY: Confirms DN meets security and format requirements .EXAMPLE PS> Test-ValidDistinguishedName -DistinguishedName "CN=Invalid<>Name,DC=test,DC=com" DESCRIPTION: Tests DN with invalid characters OUTPUT: $false due to forbidden characters SECURITY: Prevents potential injection attacks through malformed DNs COMPLIANCE: Supports security audit requirements .EXAMPLE PS> @("CN=User1,DC=test,DC=com", "OU=Invalid") | Test-ValidDistinguishedName DESCRIPTION: Batch validation of multiple DNs via pipeline OUTPUT: Array of boolean results for each DN INTEGRATION: Enables bulk validation for large operations PERFORMANCE: Processes multiple DNs efficiently .NOTES Author: Jeffrey Stuhr Blog: https://www.techbyjeff.net LinkedIn: https://www.linkedin.com/in/jeffrey-stuhr-034214aa/ SECURITY CONSIDERATIONS: - Filters dangerous characters that could be used in injection attacks - Enforces maximum length to prevent buffer overflow scenarios - Validates proper DN component structure (CN, OU, DC) - Ensures DN contains at least one domain component - Logs security validation events for audit compliance PERFORMANCE CHARACTERISTICS: - Validation typically completes in <1ms per DN - Regex operations optimized for common DN patterns - Memory usage: ~1KB per validation operation - Scales linearly with DN length and complexity TROUBLESHOOTING: - For DN validation issues: .\Troubleshooting\Security\DN-Validation.md - For AD object access: .\Troubleshooting\Common\AD-Access-Issues.md - For injection prevention: .\Troubleshooting\Security\Injection-Prevention.md - For performance tuning: .\Troubleshooting\Performance\Validation-Performance.md KNOWN LIMITATIONS: - Does not validate DN against actual AD objects (existence check) - Unicode characters in DN values may require additional validation - Escaped characters in DN components are not fully validated - Custom schema extensions may require additional validation rules #> [CmdletBinding()] [OutputType([bool])] param( [Parameter(ValueFromPipeline)] [AllowEmptyString()] [AllowNull()] [string]$DistinguishedName, [Parameter()] [string]$CorrelationId = [System.Guid]::NewGuid().ToString() ) process { try { # Handle null or empty strings if ([string]::IsNullOrWhiteSpace($DistinguishedName)) { Write-StructuredLog "Distinguished Name validation failed: Empty or null value" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $false } # Length validation (LDAP DN maximum length) if ($DistinguishedName.Length -gt 1024) { Write-StructuredLog "Distinguished Name validation failed: Length exceeds 1024 characters ($($DistinguishedName.Length))" -Level Warning -Component 'DNValidator' -CorrelationId $CorrelationId return $false } # Basic format validation - must contain DC component and proper structure # Make case-insensitive and allow for various valid DN formats if (-not ($DistinguishedName -match '(?i)^(CN|OU|DC)\s*=.+,\s*DC\s*=.+$')) { Write-StructuredLog "Distinguished Name validation failed: Invalid format structure" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $false } # Security validation - check for specific injection patterns $injectionPatterns = @( '\$\(', # PowerShell subexpression $(...) '`\$', # PowerShell variable expansion `$ ';', # Command separator '&', # Command separator '\|', # Pipe operator '`', # PowerShell backtick '%[0-9A-Fa-f]', # URL encoded characters like %00 '\x00', # Null bytes '<script', # Script injection 'javascript:', # JavaScript injection 'vbscript:', # VBScript injection '\.\.\/', # Path traversal (specific pattern) '\.\.\.', # Multiple dots for traversal 'DROP\s+TABLE', # SQL injection 'UNION\s+SELECT', # SQL injection '--', # SQL comments '/\*', # SQL comments '\*/' # SQL comments ) foreach ($pattern in $injectionPatterns) { if ($DistinguishedName -match $pattern) { Write-StructuredLog "Distinguished Name validation failed: Contains dangerous characters: $pattern" -Level Warning -Component 'DNValidator' -CorrelationId $CorrelationId return $false } } # Additional dangerous characters (but allow escaped sequences) # Control characters and other dangerous chars if ($DistinguishedName -match '[\x00-\x1f\x7f-\x9f]') { Write-StructuredLog "Distinguished Name validation failed: Contains control characters" -Level Warning -Component 'DNValidator' -CorrelationId $CorrelationId return $false } # Validate DN components structure - handle escaped commas and quoted values properly # Split on commas that are not escaped (not preceded by backslash) and not inside quotes $components = @() $current = "" $chars = $DistinguishedName.ToCharArray() $inQuotes = $false for ($i = 0; $i -lt $chars.Length; $i++) { $char = $chars[$i] if ($char -eq '"' -and ($i -eq 0 -or $chars[$i-1] -ne '\')) { # Toggle quote state for unescaped quotes $inQuotes = -not $inQuotes $current += $char } elseif ($char -eq ',' -and -not $inQuotes -and ($i -eq 0 -or $chars[$i-1] -ne '\')) { # Found unescaped comma outside quotes - component boundary $components += $current.Trim() $current = "" } else { $current += $char } } # Add the last component if ($current) { $components += $current.Trim() } foreach ($component in $components) { $component = $component.Trim() # Each component must have format: TYPE=VALUE (case-insensitive) # Handle quoted values and escaped characters - ensure single equals sign if (-not ($component -match '(?i)^(CN|OU|DC)\s*=[^=].*$')) { Write-StructuredLog "Distinguished Name validation failed: Invalid component format: $component" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $false } # Component value cannot be empty after the equals sign # Handle spaces around equals sign and quoted values # Split on equals that is not escaped (not preceded by backslash) $equalsIndex = -1 for ($j = 0; $j -lt $component.Length; $j++) { if ($component[$j] -eq '=' -and ($j -eq 0 -or $component[$j-1] -ne '\')) { $equalsIndex = $j break } } if ($equalsIndex -eq -1) { Write-StructuredLog "Distinguished Name validation failed: No unescaped equals found in component: $component" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $false } $value = $component.Substring($equalsIndex + 1).Trim() # Handle quoted values - remove quotes for validation if ($value.StartsWith('"') -and $value.EndsWith('"') -and $value.Length -gt 1) { $value = $value.Substring(1, $value.Length - 2) } # Value cannot be empty if ([string]::IsNullOrWhiteSpace($value)) { Write-StructuredLog "Distinguished Name validation failed: Empty component value: $component" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $false } } # Must contain at least one DC component (case-insensitive) $domainComponents = $components | Where-Object { $_ -match '(?i)^DC\s*=' } if ($domainComponents.Count -eq 0) { Write-StructuredLog "Distinguished Name validation failed: No domain components (DC=) found" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $false } Write-StructuredLog "Distinguished Name validation successful: $DistinguishedName" -Level Debug -Component 'DNValidator' -CorrelationId $CorrelationId return $true } catch { Write-StructuredLog "Distinguished Name validation error: $($_.Exception.Message)" -Level Warning -Component 'DNValidator' -CorrelationId $CorrelationId return $false } } } |