From 9d47ec15ef93bb50f9bfa15cf4e662155f959c3b Mon Sep 17 00:00:00 2001
From: AdminDroid <49208841+admindroid-community@users.noreply.github.com>
Date: Thu, 20 May 2021 17:14:39 +0530
Subject: [PATCH] Audit Office 365 External Sharing Activity

Audit Office 365 External Sharing Activity
---
 .../ExternalSharingReport.ps1                 | 252 ++++++++++++++++++
 1 file changed, 252 insertions(+)
 create mode 100644 Audit Office 365 External Sharing Activity/ExternalSharingReport.ps1

diff --git a/Audit Office 365 External Sharing Activity/ExternalSharingReport.ps1 b/Audit Office 365 External Sharing Activity/ExternalSharingReport.ps1
new file mode 100644
index 0000000..df0a84f
--- /dev/null
+++ b/Audit Office 365 External Sharing Activity/ExternalSharingReport.ps1	
@@ -0,0 +1,252 @@
+Param
+(
+    [Parameter(Mandatory = $false)]
+    [Nullable[DateTime]]$StartDate,
+    [Nullable[DateTime]]$EndDate,
+    [switch]$SharePointOnline,
+    [switch]$OneDrive,
+    [string]$AdminName,
+    [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
+  } 
+  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(($AdminName -ne "") -and ($Password -ne ""))
+ {
+  $SecuredPassword = ConvertTo-SecureString -AsPlainText $Password -Force
+  $Credential  = New-Object System.Management.Automation.PSCredential $AdminName,$SecuredPassword
+  Connect-ExchangeOnline -Credential $Credential
+ }
+ else
+ {
+  Connect-ExchangeOnline
+ }
+}
+
+$MaxStartDate=((Get-Date).AddDays(-89)).Date
+
+#Getting external user file access for past 90 days
+if(($StartDate -eq $null) -and ($EndDate -eq $null))
+{
+ $EndDate=(Get-Date).Date
+ $StartDate=$MaxStartDate
+}
+
+#Getting start date to generate external sharing 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 `nExternal sharing report can be retrieved only for past 90 days. Please select a date after $MaxStartDate -ForegroundColor Red
+   return
+  }
+ }
+ Catch
+ {
+  Write-Host `nNot a valid date -ForegroundColor Red
+ }
+}
+
+
+#Getting end date to generate external sharing report
+While($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
+ }
+}
+
+$OutputCSV=".\ExternalSharingReport_$((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 $CurrentEnd)
+{
+ Write-Host Start and end time are same.Please enter different time range -ForegroundColor Red
+ Exit
+}
+
+Connect_EXO
+$AggregateResults = @()
+$CurrentResult= @()
+$CurrentResultCount=0
+$AggregateResultCount=0
+Write-Host `nRetrieving external sharing events from $StartDate to $EndDate...
+$ProcessedAuditCount=0
+$OutputEvents=0
+$ExportResult=""   
+$ExportResults=@()  
+
+while($true)
+{ 
+ #Getting exteranl sharing audit data for given time range
+ $Results=Search-UnifiedAuditLog -StartDate $CurrentStart -EndDate $CurrentEnd -Operations "Sharinginvitationcreated,AnonymousLinkcreated,AddedToSecureLink" -SessionId s -SessionCommand ReturnLargeSet -ResultSize 5000
+ $ResultCount=($Results | Measure-Object).count
+ foreach($Result in $Results)
+ {
+  $ProcessedAuditCount++
+  $MoreInfo=$Result.auditdata
+  $Operation=$Result.Operations
+  $AuditData=$Result.auditdata | ConvertFrom-Json
+  $Workload=$AuditData.Workload
+
+  #Filter for SharePointOnline external Sharing events
+  If($SharePointOnline.IsPresent -and ($Workload -eq "OneDrive"))
+  {
+   continue
+  }
+
+  If($OneDrive.IsPresent -and ($Workload -eq "SharePoint"))
+  {
+   continue
+  }
+  
+  #Check for Guest sharing
+  if($Operation -ne "AnonymousLinkcreated")
+  {
+   If($AuditData.TargetUserOrGroupType -ne "Guest")
+   {
+    continue
+   }
+   $SharedWith=$AuditData.TargetUserOrGroupName
+  }
+  else
+  {
+   $SharedWith="Anyone with the link can access"
+  }
+
+  $ActivityTime=Get-Date($AuditData.CreationTime) -format g
+  $SharedBy=$AuditData.userId
+  $SharedResourceType=$AuditData.ItemType
+  $sharedResource=$AuditData.ObjectId
+  $SiteURL=$AuditData.SiteURL
+  
+
+  #Export result to csv
+  $OutputEvents++
+  $ExportResult=@{'Shared Time'=$ActivityTime;'Sharing Type'=$Operation;'Shared By'=$SharedBy;'Shared With'=$SharedWith;'Shared Resource Type'=$SharedResourceType;'Shared Resource'=$SharedResource;'Site url'=$Siteurl;'Workload'=$Workload;'More Info'=$MoreInfo}
+  $ExportResults= New-Object PSObject -Property $ExportResult  
+  $ExportResults | Select-Object 'Shared Time','Shared By','Shared With','Shared Resource Type','Shared Resource','Site URL','Sharing Type','Workload','More Info' | Export-Csv -Path $OutputCSV -Notype -Append 
+ }
+ Write-Progress -Activity "`n     Retrieving external sharing events from $CurrentStart to $CurrentEnd.."`n" Processed audit record count: $ProcessedAuditCount"
+ $currentResultCount=$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
+   $CurrentResult = @()
+   if($CurrentEnd -gt $EndDate)
+   {
+    $CurrentEnd=$EndDate
+   }
+  }
+  else
+  {
+   Write-Host Please rerun the script with reduced time interval -ForegroundColor Red
+   Exit
+  }
+ }
+
+ 
+ if($Results.count -lt 5000)
+ {
+  #$AggregateResultCount +=$CurrentResultCount
+  if($CurrentEnd -eq $EndDate)
+  {
+   break
+  }
+  $CurrentStart=$CurrentEnd 
+  if($CurrentStart -gt (Get-Date))
+  {
+   break
+  }
+  $CurrentEnd=$CurrentStart.AddMinutes($IntervalTimeInMinutes)
+  $CurrentResultCount=0
+  $CurrentResult = @()
+  if($CurrentEnd -gt $EndDate)
+  {
+   $CurrentEnd=$EndDate
+  }
+ }
+}
+
+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 availble 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