<#
.TITLE
    Policy Changes Monitor

.SYNOPSIS
    Monitor and report on recent changes to Policies in Microsoft Intune.

.DESCRIPTION
    This script connects to Microsoft Graph and retrieves recent changes to Policies
    configured in Intune. It checks audit logs for policy modifications, creations, deletions, and
    assignments within a specified time period. The script generates detailed reports in CSV format,
    highlighting policy changes with details about who made the changes, when they occurred, and
    what was modified. This helps administrators track configuration drift and maintain governance
    over device configuration policies.

.TAGS
    Monitoring

.MINROLE
    Intune Administrator

.PERMISSIONS
    DeviceManagementApps.Read.All,Mail.Send

.AUTHOR
    Ugur Koc

.VERSION
    1.4

.CHANGELOG
    1.4 - Added Azure Automation contract validation, portal-safe boolean parameters, beta Graph endpoints, and terminating paging errors
    1.3 - Azure Automation now records script progress, outcomes, and summaries in job history
    1.2 - Audit log filter timestamp is now built from UTC; severity check on activityResult is now case-insensitive (Graph returns "Success"/"Failure" capitalized); output directory is created automatically before the CSV export; pagination helper keeps single-item results as arrays
    1.1 - Local runs now use MgGraphCommunity for WAM-free interactive sign-in (auto-installed if missing)
    1.0 - Initial release

.LASTUPDATE
    2026-07-30

.EXAMPLE
    .\check-policy-changes.ps1
    Generates a report of policy changes from the last 30 days

.EXAMPLE
    .\check-policy-changes.ps1 -DaysBack 30 -OutputPath "C:\Reports"
    Generates a report of policy changes from the last 30 days and saves to specified directory

.EXAMPLE
    .\check-policy-changes.ps1 -OnlyShowChanges "true" -SendEmailAlert "true" -AlertEmailAddress "<recipient-address>" -SenderUPN "<sender-upn>"
    Shows only modified policies and sends email alerts for changes

.NOTES
    - Requires Microsoft.Graph.Authentication module: Install-Module Microsoft.Graph.Authentication
    - Requires appropriate permissions in Entra ID
    - Email alerts require Mail.Send and a runtime-supplied SenderUPN and recipient address
    - Policies use modern configuration templates
    - Policies require beta Graph endpoint access
    - Audit data is available for up to 30 days by default
    - Critical for maintaining configuration governance and compliance
    - Monitor for unauthorized changes to security policies
    - Local interactive sign-in uses the MgGraphCommunity module to avoid the Graph SDK's mandatory WAM broker on Windows
#>

[CmdletBinding()]
param(
    [Parameter(Mandatory = $false, HelpMessage = "Number of days to look back for changes")]
    [ValidateRange(1, 90)]
    [int]$DaysBack = 30,

    [Parameter(Mandatory = $false, HelpMessage = "Directory path to save reports")]
    [ValidateNotNullOrEmpty()]
    [string]$OutputPath = ".",

    [Parameter(Mandatory = $false, HelpMessage = "Only show policies with changes")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$OnlyShowChanges,

    [Parameter(Mandatory = $false, HelpMessage = "Send email alert for policy changes")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$SendEmailAlert,

    [Parameter(Mandatory = $false, HelpMessage = "Email address to send alerts to")]
    [string]$AlertEmailAddress = "",

    [Parameter(Mandatory = $false, HelpMessage = "Mailbox UPN used to send alerts")]
    [string]$SenderUPN = "",

    [Parameter(Mandatory = $false, HelpMessage = "Include detailed change information")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$IncludeDetails,

    [Parameter(Mandatory = $false, HelpMessage = "Force module installation without prompting")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$ForceModuleInstall
)

# Normalize the local module-install override for Azure Automation parameter binding.
$forceModuleInstallRaw = [string]$ForceModuleInstall
Remove-Variable -Name ForceModuleInstall
if ([string]::IsNullOrWhiteSpace($forceModuleInstallRaw)) {
    $ForceModuleInstall = $false
}
elseif ($forceModuleInstallRaw.Trim().ToLowerInvariant() -in @("true", "1", '$true')) {
    $ForceModuleInstall = $true
}
elseif ($forceModuleInstallRaw.Trim().ToLowerInvariant() -in @("false", "0", '$false')) {
    $ForceModuleInstall = $false
}
else {
    throw "Parameter 'ForceModuleInstall' accepts only true, false, 1, 0, $true, or $false."
}

# Azure Automation supplies portal parameter values as strings. Normalize the
# public boolean parameters once so local and runbook execution use real booleans.
foreach ($runbookBooleanParameter in @('OnlyShowChanges', 'SendEmailAlert', 'IncludeDetails')) {
    $runbookBooleanRaw = [string](Get-Variable -Name $runbookBooleanParameter -ValueOnly)
    Remove-Variable -Name $runbookBooleanParameter

    if ([string]::IsNullOrWhiteSpace($runbookBooleanRaw)) {
        Set-Variable -Name $runbookBooleanParameter -Value $false
        continue
    }

    switch ($runbookBooleanRaw.Trim().ToLowerInvariant()) {
        { $_ -in @("true", "1", '$true') } {
            Set-Variable -Name $runbookBooleanParameter -Value $true
        }
        { $_ -in @("false", "0", '$false') } {
            Set-Variable -Name $runbookBooleanParameter -Value $false
        }
        default {
            throw "Parameter '$runbookBooleanParameter' accepts only true, false, 1, 0, $true, or $false."
        }
    }
}

# ============================================================================
# ENVIRONMENT DETECTION AND SETUP
# ============================================================================

function Initialize-RequiredModule {
    <#
    .SYNOPSIS
    Ensures required modules are available and loaded
    #>
    param(
        [string[]]$ModuleNames,
        [bool]$IsAutomationEnvironment,
        [bool]$ForceInstall = $false
    )

    foreach ($ModuleName in $ModuleNames) {
        Write-Verbose "Checking module: $ModuleName"

        # Check if module is available
        $module = Get-Module -ListAvailable -Name $ModuleName | Select-Object -First 1

        if (-not $module) {
            if ($IsAutomationEnvironment) {
                $errorMessage = @"
Module '$ModuleName' is not available in this Azure Automation Account.

To resolve this issue:
1. Go to Azure Portal
2. Navigate to your Automation Account
3. Go to 'Modules' > 'Browse Gallery'
4. Search for '$ModuleName'
5. Click 'Import' and wait for installation to complete

Alternative: Use PowerShell to import the module:
Import-Module Az.Automation
Import-AzAutomationModule -AutomationAccountName "YourAccount" -ResourceGroupName "YourRG" -Name "$ModuleName"
"@
                throw $errorMessage
            }
            else {
                # Local environment - attempt to install
                Write-Information "Module '$ModuleName' not found. Attempting to install..." -InformationAction Continue

                if (-not $ForceInstall) {
                    $response = Read-Host "Install module '$ModuleName'? (Y/N)"
                    if ($response -notmatch '^[Yy]') {
                        throw "Module '$ModuleName' is required but installation was declined."
                    }
                }

                try {
                    # Check if running as administrator for AllUsers scope
                    $isAdmin = ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")
                    $scope = if ($isAdmin) { "AllUsers" } else { "CurrentUser" }

                    Write-Information "Installing '$ModuleName' in scope '$scope'..." -InformationAction Continue
                    Install-Module -Name $ModuleName -Scope $scope -Force -AllowClobber -Repository PSGallery
                    Write-Information "✓ Successfully installed '$ModuleName'" -InformationAction Continue
                }
                catch {
                    throw "Failed to install module '$ModuleName': $($_.Exception.Message)"
                }
            }
        }

        # Import the module
        try {
            Write-Verbose "Importing module: $ModuleName"
            Import-Module -Name $ModuleName -Force -ErrorAction Stop
            Write-Verbose "✓ Successfully imported '$ModuleName'"
        }
        catch {
            throw "Failed to import module '$ModuleName': $($_.Exception.Message)"
        }
    }
}

# Detect execution environment
if ($PSPrivateMetadata.JobId.Guid) {
    Write-Output "Running inside Azure Automation Runbook"
    $IsAzureAutomation = $true
}
else {
    Write-Output "Running locally in IDE or terminal"
    $IsAzureAutomation = $false
}

# Initialize required modules
$RequiredModules = @(
    "Microsoft.Graph.Authentication"
)

# MgGraphCommunity gives WAM-free interactive sign-in for local runs
if (-not $IsAzureAutomation) {
    $RequiredModules += "MgGraphCommunity"
}

try {
    Initialize-RequiredModule -ModuleNames $RequiredModules -IsAutomationEnvironment $IsAzureAutomation -ForceInstall $ForceModuleInstall
    Write-Verbose "✓ All required modules are available"
}
catch {
    Write-Error "Module initialization failed: $_"
    exit 1
}

# ============================================================================
# AUTHENTICATION
# ============================================================================

try {
    if ($IsAzureAutomation) {
        # Azure Automation - Use Managed Identity
        Write-Output "Connecting to Microsoft Graph using Managed Identity..."
        Connect-MgGraph -Identity -NoWelcome -ErrorAction Stop
        Write-Output "✓ Successfully connected to Microsoft Graph using Managed Identity"
    }
    else {
        # Local execution - WAM-free interactive sign-in via MgGraphCommunity
        Write-Output "Connecting to Microsoft Graph with interactive authentication..."
        $Scopes = @(
            "DeviceManagementApps.Read.All",
            "Mail.Send"
        )
        Connect-MgGraphCommunity -Scopes $Scopes -NoWelcome -ErrorAction Stop
        Write-Output "✓ Successfully connected to Microsoft Graph"
    }
}
catch {
    Write-Error "Failed to connect to Microsoft Graph: $($_.Exception.Message)"
    exit 1
}

# ============================================================================
# HELPER FUNCTIONS
# ============================================================================

# Function to get all pages of results from Graph API
function Get-MgGraphAllPage {
    param(
        [Parameter(Mandatory = $true)]
        [string]$Uri,
        [int]$DelayMs = 100
    )

    $AllResults = @()
    $NextLink = $Uri
    $RequestCount = 0

    do {
        try {
            # Add delay to respect rate limits
            if ($RequestCount -gt 0) {
                Start-Sleep -Milliseconds $DelayMs
            }

            $Response = Invoke-MgGraphRequest -Uri $NextLink -Method GET
            $RequestCount++

            if ($null -ne $Response.value) {
                $AllResults += $Response.value
            }
            else {
                $AllResults += $Response
            }

            $NextLink = $Response.'@odata.nextLink'
        }
        catch {
            if ($_.Exception.Message -like "*429*" -or $_.Exception.Message -like "*throttled*") {
                Write-Information "`nRate limit hit, waiting 60 seconds..." -InformationAction Continue
                Start-Sleep -Seconds 60
                continue
            }
            throw "Error fetching data from $NextLink : $($_.Exception.Message)"
        }
    } while ($NextLink)

    # Comma prevents unrolling so single-element results stay arrays
    return , $AllResults
}

# Function to format change details
function Format-ChangeDetail {
    param(
        [object]$AuditLog
    )

    $ChangeDetails = @()

    if ($AuditLog.resources) {
        foreach ($Resource in $AuditLog.resources) {
            if ($Resource.modifiedProperties) {
                foreach ($Property in $Resource.modifiedProperties) {
                    $ChangeDetail = [PSCustomObject]@{
                        PropertyName = $Property.displayName
                        OldValue     = if ($Property.oldValue) { $Property.oldValue -replace "`n", " " } else { "N/A" }
                        NewValue     = if ($Property.newValue) { $Property.newValue -replace "`n", " " } else { "N/A" }
                    }
                    $ChangeDetails += $ChangeDetail
                }
            }
        }
    }

    return $ChangeDetails
}

# Function to determine change severity
function Get-ChangeSeverity {
    param(
        [string]$Activity,
        [string]$Result
    )

    # Graph returns "Success"/"Failure" capitalized; normalize so casing never matters
    if ($Result.ToLower() -eq "failure") {
        return "High"
    }

    switch -Wildcard ($Activity) {
        "*Delete*" { return "High" }
        "*Create*" { return "Medium" }
        "*Update*" { return "Medium" }
        "*Assign*" { return "Low" }
        default { return "Low" }
    }
}

function Send-PolicyChangeEmail {
    param(
        [Parameter(Mandatory = $true)]
        [object[]]$Changes,

        [Parameter(Mandatory = $true)]
        [string]$RecipientAddresses,

        [Parameter(Mandatory = $true)]
        [string]$SenderUserPrincipalName
    )

    $toRecipients = @(
        $RecipientAddresses -split '[,;]' |
            ForEach-Object { $_.Trim() } |
            Where-Object { -not [string]::IsNullOrWhiteSpace($_) } |
            ForEach-Object {
                try {
                    $validatedAddress = [System.Net.Mail.MailAddress]::new($_).Address
                }
                catch {
                    throw "Invalid alert email address '$_'."
                }

                @{ emailAddress = @{ address = $validatedAddress } }
            }
    )
    if ($toRecipients.Count -eq 0) {
        throw "At least one alert email address is required."
    }

    $changeLines = @(
        $Changes | Select-Object -First 10 | ForEach-Object {
            "$($_.DateTime): $($_.PolicyName) - $($_.Action) by $($_.User)"
        }
    )
    $bodyText = @"
Policy Changes Report

Time period: Last $DaysBack days
Total changes: $($Changes.Count)

Recent changes:
$($changeLines -join [Environment]::NewLine)

Review the Intune audit log for full details.
"@
    $payload = @{
        message = @{
            subject = "Policy Changes Alert - $($Changes.Count) changes detected"
            body = @{
                contentType = "Text"
                content = $bodyText
            }
            toRecipients = $toRecipients
        }
        saveToSentItems = $true
    }

    $encodedSender = [uri]::EscapeDataString($SenderUserPrincipalName)
    $mailUri = "https://graph.microsoft.com/beta/users/$encodedSender/sendMail"
    Invoke-MgGraphRequest -Uri $mailUri -Method POST -Body ($payload | ConvertTo-Json -Depth 10) -ContentType "application/json" -ErrorAction Stop | Out-Null
}

# ============================================================================
# MAIN SCRIPT LOGIC
# ============================================================================

try {
    Write-Output "Starting Policies changes analysis..."

    # Calculate start date in UTC so the filter matches Graph timestamps
    $StartDate = (Get-Date).ToUniversalTime().AddDays(-$DaysBack)
    $StartDateFormatted = $StartDate.ToString("yyyy-MM-ddTHH:mm:ssZ")

    Write-Output "Analyzing changes from: $($StartDate.ToString('yyyy-MM-dd HH:mm:ss'))"

    # ========================================================================
    # GET AUDIT LOGS FOR SETTINGS CATALOG CHANGES
    # ========================================================================

    Write-Output "Retrieving audit logs for Policies changes..."

    try {
        # Query for Policies changes (DeviceConfiguration category)
        $AuditLogsUri = "https://graph.microsoft.com/beta/deviceManagement/auditEvents?`$filter=activityDateTime ge $StartDateFormatted and category eq 'DeviceConfiguration'&`$orderby=activityDateTime desc&`$top=50"
        $AuditLogs = Get-MgGraphAllPage -Uri $AuditLogsUri

        Write-Output "Retrieved $($AuditLogs.Count) DeviceConfiguration audit events"

        # Filter for Policies (DeviceManagementConfigurationPolicy) activities
        $PoliciesActivities = $AuditLogs | Where-Object {
            $_.activityType -like "*DeviceManagementConfigurationPolicy*"
        }

        Write-Output "✓ Found $($PoliciesActivities.Count) policy changes"
    }
    catch {
        throw "Failed to retrieve audit logs: $($_.Exception.Message)"
    }

    # ========================================================================
    # FILTER AND PROCESS CHANGES
    # ========================================================================

    Write-Output "Processing Policies policy changes..."

    # Filter changes if OnlyShowChanges is specified
    if ($OnlyShowChanges) {
        $PoliciesActivities = $PoliciesActivities | Where-Object {
            $_.activityType -like "*Update*" -or $_.activityType -like "*Modify*"
        }
        Write-Output "Filtered to show only policy modifications: $($PoliciesActivities.Count) changes"
    }

    # Get the last 5 changes
    $Last5Changes = $PoliciesActivities | Select-Object -First 5

    if ($Last5Changes.Count -eq 0) {
        Write-Output "No Policies policy changes found in the specified time period."
        return
    }

    Write-Output "`n========================================"
    Write-Output "LAST 5 POLICIES POLICY CHANGES"
    Write-Output "========================================"

    # Prepare CSV data for export
    $CsvData = @()

    $ChangeNumber = 1
    foreach ($Change in $Last5Changes) {
        try {
            # Get policy name and user info
            $PolicyName = "Unknown Policy"
            $UserName = "System"

            if ($Change.resources -and $Change.resources.Count -gt 0) {
                $PolicyName = $Change.resources[0].displayName
            }

            if ($Change.actor -and $Change.actor.userPrincipalName) {
                $UserName = $Change.actor.userPrincipalName
            }

            Write-Output "`n[$ChangeNumber] $($Change.activityDateTime)"
            Write-Output "Policy: $PolicyName"
            Write-Output "Action: $($Change.activityType)"
            Write-Output "User: $UserName"
            Write-Output "Result: $($Change.activityResult)"

            # Collect change details for CSV export
            $ChangeDetails = ""
            $Severity = Get-ChangeSeverity -Activity $Change.activityType -Result $Change.activityResult

            # Show modified properties (before/after values)
            if ($Change.resources -and $Change.resources[0].modifiedProperties) {
                Write-Output "Changes:"
                $ChangeDetailsList = @()
                foreach ($Property in $Change.resources[0].modifiedProperties) {
                    $OldValue = if ($Property.oldValue) { $Property.oldValue } else { "(empty)" }
                    $NewValue = if ($Property.newValue) { $Property.newValue } else { "(empty)" }
                    Write-Output "  - $($Property.displayName): '$OldValue' → '$NewValue'"

                    if ($IncludeDetails) {
                        $ChangeDetailsList += "$($Property.displayName): '$OldValue' → '$NewValue'"
                    }
                }
                $ChangeDetails = $ChangeDetailsList -join "; "
            }
            else {
                Write-Output "  No detailed change information available"
            }

            # Add to CSV data
            $CsvRecord = [PSCustomObject]@{
                DateTime   = $Change.activityDateTime
                PolicyName = $PolicyName
                Action     = $Change.activityType
                User       = $UserName
                Result     = $Change.activityResult
                Severity   = $Severity
                Details    = if ($IncludeDetails) { $ChangeDetails } else { "" }
            }
            $CsvData += $CsvRecord

            $ChangeNumber++
        }
        catch {
            Write-Warning "Error processing change: $($_.Exception.Message)"
            continue
        }
    }

    # ========================================================================
    # EXPORT TO CSV
    # ========================================================================

    if ($CsvData.Count -gt 0) {
        # Create output directory if it does not exist
        if (-not (Test-Path $OutputPath)) {
            New-Item -Path $OutputPath -ItemType Directory -Force | Out-Null
            Write-Output "Created output directory: $OutputPath"
        }

        $OutputFile = Join-Path -Path $OutputPath -ChildPath "PolicyChanges_$(Get-Date -Format 'yyyyMMdd_HHmmss').csv"
        try {
            $CsvData | Export-Csv -Path $OutputFile -NoTypeInformation -Encoding UTF8
            Write-Output "✓ Report exported to: $OutputFile"
        }
        catch {
            Write-Warning "Failed to export CSV report: $($_.Exception.Message)"
        }
    }

    # ========================================================================
    # EMAIL ALERTS
    # ========================================================================

    if ($SendEmailAlert) {
        if ([string]::IsNullOrWhiteSpace($AlertEmailAddress)) {
            throw "AlertEmailAddress is required when SendEmailAlert is enabled."
        }
        if ([string]::IsNullOrWhiteSpace($SenderUPN)) {
            throw "SenderUPN is required when SendEmailAlert is enabled."
        }

        if ($CsvData.Count -gt 0) {
            Send-PolicyChangeEmail -Changes $CsvData -RecipientAddresses $AlertEmailAddress -SenderUserPrincipalName $SenderUPN
            Write-Output "✓ Policy change email sent."
        }
        else {
            Write-Output "No policy changes detected. Email alert was not sent."
        }
    }

    Write-Output "`n✓ Policies changes analysis completed successfully"
}
catch {
    Write-Error "Script failed: $($_.Exception.Message)"
    exit 1
}
finally {
    # Cleanup operations
    try {
        Disconnect-MgGraph -ErrorAction SilentlyContinue | Out-Null
        Write-Output "Disconnected from Microsoft Graph"
    }
    catch {
        Write-Warning "Failed to disconnect from Microsoft Graph: $($_.Exception.Message)"
    }
}

# ============================================================================
# SCRIPT SUMMARY
# ============================================================================

Write-Output "
========================================
Script Execution Summary
========================================
Script: Policies Changes Monitor
Time Period: Last $DaysBack days
Status: Completed
========================================
"

# Copia sin cambios de https://github.com/ugurkocde/IntuneAutomation (commit 797bb2e).
# MIT License
#
# Copyright (c) 2025 Ugur Koc | Microsoft MVP
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.