From 8601f1f840202df56738a2acbfa213e792e7b078 Mon Sep 17 00:00:00 2001
From: AdminDroid <49208841+admindroid-community@users.noreply.github.com>
Date: Wed, 20 Jul 2022 14:22:49 +0530
Subject: [PATCH] Audit Mailbox Permission Changes

Audit Mailbox Permission Changes
---
 .../AuditMailboxPermissionChanges.ps1         | 303 ++++++++++++++++++
 1 file changed, 303 insertions(+)
 create mode 100644 Audit Mailbox Permission Changes/AuditMailboxPermissionChanges.ps1

diff --git a/Audit Mailbox Permission Changes/AuditMailboxPermissionChanges.ps1 b/Audit Mailbox Permission Changes/AuditMailboxPermissionChanges.ps1
new file mode 100644
index 0000000..9dd40d6
--- /dev/null
+++ b/Audit Mailbox Permission Changes/AuditMailboxPermissionChanges.ps1	
@@ -0,0 +1,303 @@
+<#
+=============================================================================================
+Name:           Audit mailbox permission changes in Office 365
+Version:        1.0
+Website:        o365reports.com
+Script by:      O365Reports Team
+For detailed script execution:  https://o365reports.com/2022/07/06/audit-mailbox-permission-changes-in-office-365-powershell
+============================================================================================
+#>
+
+Param
+(
+    [Parameter(Mandatory = $false)]
+    [Nullable[DateTime]]$StartDate,
+    [Nullable[DateTime]]$EndDate,
+    [switch]$SendAsOnly,
+    [switch]$SendOnBehalfOnly,
+    [switch]$FullAccessOnly,
+    [string]$UserName,
+    [string]$Password
+)
+
+Function Connect_Exo
+{
+ #Check for EXO v2 module inatallation
+ $Module = Get-Module ExchangeOnlineManagement -ListAvailable
+ if($Module.count -eq 0) 
+ { 
+  Write-Host Exchange Online PowerShell V2 module is not available  -ForegroundColor yellow  
+  $Confirm= Read-Host Are you sure you want to install module? [Y] Yes [N] No 
+  if($Confirm -match "[yY]") 
+  { 
+   Write-host "Installing Exchange Online PowerShell module"
+   Install-Module ExchangeOnlineManagement -Repository PSGallery -AllowClobber -Force
+   Import-Module ExchangeOnlineManagement
+  } 
+  else 
+  { 
+   Write-Host EXO V2 module is required to connect Exchange Online.Please install module using Install-Module ExchangeOnlineManagement cmdlet. 
+   Exit
+  }
+ } 
+ Write-Host Connecting to Exchange Online...
+ #Storing credential in script for scheduling purpose/ Passing credential as parameter - Authentication using non-MFA account
+ if(($UserName -ne "") -and ($Password -ne ""))
+ {
+  $SecuredPassword = ConvertTo-SecureString -AsPlainText $Password -Force
+  $Credential  = New-Object System.Management.Automation.PSCredential $UserName,$SecuredPassword
+  Connect-ExchangeOnline -Credential $Credential
+ }
+ else
+ {
+  Connect-ExchangeOnline
+ }
+}
+
+$MaxStartDate=((Get-Date).AddDays(-89)).Date
+
+#Audit mailbox permission changes for past 90 days
+if(($StartDate -eq $null) -and ($EndDate -eq $null))
+{
+ $EndDate=(Get-Date).Date
+ $StartDate=$MaxStartDate
+}
+#Getting start date to audit mailbox permission changes report
+While($true)
+{
+ if ($StartDate -eq $null)
+ {
+  $StartDate=Read-Host Enter start time for report generation '(Eg:04/28/2021)'
+ }
+ Try
+ {
+  $Date=[DateTime]$StartDate
+  if($Date -ge $MaxStartDate)
+  { 
+   break
+  }
+  else
+  {
+   Write-Host `nAudit can be retrieved only for past 90 days. Please select a date after $MaxStartDate -ForegroundColor Red
+   return
+  }
+ }
+ Catch
+ {
+  Write-Host `nNot a valid date -ForegroundColor Red
+ }
+}
+
+
+#Getting end date to audit mailbox permission changes changes report
+While($true)
+{
+ if ($EndDate -eq $null)
+ {
+  $EndDate=Read-Host Enter End time for report generation '(Eg: 04/28/2021)'
+ }
+ Try
+ {
+  $Date=[DateTime]$EndDate
+  if($EndDate -lt ($StartDate))
+  {
+   Write-Host End time should be later than start time -ForegroundColor Red
+   return
+  }
+  break
+ }
+ Catch
+ {
+  Write-Host `nNot a valid date -ForegroundColor Red
+ }
+}
+
+$OutputCSV=".\AuditMailboxPermissionChanges_$((Get-Date -format yyyy-MMM-dd-ddd` hh-mm` tt).ToString()).csv" 
+$IntervalTimeInMinutes=1440    #$IntervalTimeInMinutes=Read-Host Enter interval time period '(in minutes)'
+$CurrentStart=$StartDate
+$CurrentEnd=$CurrentStart.AddMinutes($IntervalTimeInMinutes)
+
+#Check whether CurrentEnd exceeds EndDate
+if($CurrentEnd -gt $EndDate)
+{
+ $CurrentEnd=$EndDate
+}
+
+if($CurrentStart -eq $CurrentEnd)
+{
+ Write-Host Start and end time are same.Please enter different time range -ForegroundColor Red
+ Exit
+}
+
+Connect_EXO
+$CurrentResultCount=0
+$AggregateResultCount=0
+Write-Host `nAuditing mailbox permission changes from $StartDate to $EndDate...
+$ProcessedAuditCount=0
+$OutputEvents=0
+$ExportResult=""   
+$ExportResults=@()  
+
+#Determine the operations based on the user's input
+If($SendAsOnly.IsPresent)
+{
+ $Operations="Add-RecipientPermission,Remove-RecipientPermission"
+}
+elseif($SendOnBehalfOnly.IsPresent)
+{
+ $Operations="Set-mailbox"
+}
+elseif($FullAccessOnly.IsPresent)
+{
+ $Operations="Add-MailboxPermission,Remove-MailboxPermission"
+}
+else
+{
+ $Operations="Add-RecipientPermission,Remove-RecipientPermission,Set-mailbox,Add-MailboxPermission,Remove-MailboxPermission"
+}
+
+
+while($true)
+{
+ #Getting audit data for the given time range
+ Search-UnifiedAuditLog -StartDate $CurrentStart -EndDate $CurrentEnd -Operations $Operations -SessionId s -SessionCommand ReturnLargeSet -ResultSize 5000 | ForEach-Object {
+  $ResultCount++
+  $ProcessedAuditCount++
+  Write-Progress -Activity "`n     Retrieving mailbox permission changes from $CurrentStart to $CurrentEnd.."`n" Processed audit record count: $ProcessedAuditCount"
+  $MoreInfo=$_.auditdata
+  $Operation=$_.Operations
+  $User=$_.UserIds
+  $PrintFlag="True"
+  if($user -like "NT Authority*")
+  {
+   $PrintFlag="False"
+  } 
+  $AuditData=$_.auditdata | ConvertFrom-Json
+  $EventTime=(Get-Date($AuditData.CreationTime)).ToLocalTime()  #Get-Date($AuditData.CreationTime) Uncomment to view the Activity Time in UTC
+ 
+  #Check for sendonbehalf operation
+  if(($Operation -eq "Set-Mailbox") -and ($auditData.Parameters.name -contains "GrantSendOnBehalfTo"))
+  { 
+   $MailboxInfo=$AuditData.Parameters.Value[0]
+   $DelegateInfo=$AuditData.Parameters.Value[1]
+   $MailboxName=($MailboxInfo -split "/") | Select-Object -Last 1
+   if($DelegateInfo -like "*Microsoft Exchange Hosted*")
+   {
+    $Permission="Adding send on behalf permission"
+    $Delegate= ($DelegateInfo -split "/") | Select-Object -Last 1
+   }
+   else
+   {
+    if($DelegateInfo -eq "")
+   {
+    $DelegateInfo="-"
+   }
+    $Permission="Removing send on behalf permission"
+    $Delegate="Current Delegates:"+ $DelegateInfo
+   }
+  }
+  elseif($Operation -eq "Set-Mailbox")
+  {
+   $PrintFlag="False"
+  }
+  else
+  {
+   $MailboxInfo=$AuditData.Parameters.Value[0]
+   $DelegateInfo=$AuditData.Parameters.Value[1]
+   $MailboxName=($MailboxInfo -split "/") | Select-Object -Last 1
+   $Delegate=$Delegate= ($DelegateInfo -split "/") | Select-Object -Last 1
+   if($Operation -eq "Add-RecipientPermission")
+   {
+    $Permission="Adding send as permission"
+   }
+   elseif($Operation -eq "Remove-RecipientPermission")
+   {
+    $Permission="Removing send as permission"
+   }
+   elseif($Operation -eq "Add-MailboxPermission")
+   {
+    $Permission="Adding full access permission"
+   }
+   elseif($Operation -eq "Remove-MailboxPermission")
+   {
+    $Permission="Removing full access permission"
+   }
+  }
+
+  #Export result to csv
+  if($PrintFlag -eq "True")
+  {
+   $OutputEvents++
+   $ExportResult=@{'Event Time'=$EventTime;'Performed By'=$User; 'Permission'=$Permission;'Mailbox Name'=$MailboxName;'Delegate Name'=$Delegate;'More Info'=$MoreInfo}
+   $ExportResults= New-Object PSObject -Property $ExportResult  
+   $ExportResults | Select-Object 'Event Time','Permission','Performed By','Mailbox Name','Delegate Name','More Info' | Export-Csv -Path $OutputCSV -Notype -Append 
+  }
+ }
+ $currentResultCount=$currentResultCount+$ResultCount
+ 
+ if($CurrentResultCount -ge 50000)
+ {
+  Write-Host Retrieved max record for current range.Proceeding further may cause data loss or rerun the script with reduced time interval. -ForegroundColor Red
+  $Confirm=Read-Host `nAre you sure you want to continue? [Y] Yes [N] No
+  if($Confirm -match "[Y]")
+  {
+   Write-Host Proceeding audit log collection with data loss
+   [DateTime]$CurrentStart=$CurrentEnd
+   [DateTime]$CurrentEnd=$CurrentStart.AddMinutes($IntervalTimeInMinutes)
+   $CurrentResultCount=0
+   if($CurrentEnd -gt $EndDate)
+   {
+    $CurrentEnd=$EndDate
+   }
+  }
+  else
+  {
+   Write-Host Please rerun the script with reduced time interval -ForegroundColor Red
+   Exit
+  }
+ }
+ 
+ if($ResultCount -lt 5000)
+ { 
+  if($CurrentEnd -eq $EndDate)
+  {
+   break
+  }
+  $CurrentStart=$CurrentEnd 
+  if($CurrentStart -gt (Get-Date))
+  {
+   break
+  }
+  $CurrentEnd=$CurrentStart.AddMinutes($IntervalTimeInMinutes)
+  $CurrentResultCount=0
+  if($CurrentEnd -gt $EndDate)
+  {
+   $CurrentEnd=$EndDate
+  }
+ }                                                                                             
+ $ResultCount=0
+}
+
+#Open output file after execution
+If($OutputEvents -eq 0)
+{
+ Write-Host No records found
+}
+else
+{
+ Write-Host `nThe output file contains $OutputEvents audit records
+ if((Test-Path -Path $OutputCSV) -eq "True") 
+ {
+  Write-Host `nThe Output file available in $OutputCSV -ForegroundColor Green
+  $Prompt = New-Object -ComObject wscript.shell   
+  $UserInput = $Prompt.popup("Do you want to open output file?",`   
+ 0,"Open Output File",4)   
+  If ($UserInput -eq 6)   
+  {   
+   Invoke-Item "$OutputCSV"   
+  } 
+ }
+}
+
+#Disconnect Exchange Online session
+Disconnect-ExchangeOnline -Confirm:$false -InformationAction Ignore -ErrorAction SilentlyContinue
\ No newline at end of file