fix an error

Get-UserLogonActivity.ps1

@@ -36,6 +36,33 @@ Function Test-ActivityDateRangeValue {
     Return $true
 }
 
+Function Get-UserLogonActivityErrorMessage {
+    Param(
+        [AllowNull()]
+        [object]$ErrorRecord,
+
+        [string]$FallbackMessage = 'Unknown error.'
+    )
+
+    $Message = ''
+
+    If ($null -ne $ErrorRecord) {
+        If ($null -ne $ErrorRecord.Exception) {
+            $Message = [string]$ErrorRecord.Exception.Message
+        }
+
+        If ([string]::IsNullOrWhiteSpace($Message)) {
+            $Message = [string]$ErrorRecord
+        }
+    }
+
+    If ([string]::IsNullOrWhiteSpace($Message)) {
+        $Message = $FallbackMessage
+    }
+
+    Return $Message
+}
+
 $StartHasValue = ($null -ne $StartVariable -and (Test-ActivityDateRangeValue -Value $StartVariable.Value))
 $EndHasValue = ($null -ne $EndVariable -and (Test-ActivityDateRangeValue -Value $EndVariable.Value))
 
@@ -585,13 +612,38 @@ Function Write-UserLogonActivityOutput {
     Write-Output (($Rows | Format-Table -AutoSize | Out-String -Width 240).TrimEnd())
 }
 
+Function Test-RedundantSessionReconnectUnlock {
+    Param(
+        [Parameter(Mandatory=$true)]
+        [object]$ActivityEvent,
+
+        [AllowNull()]
+        [object[]]$ActivityEvents
+    )
+
+    If ($ActivityEvent.Activity -ne 'unlock' -or $ActivityEvent.Source -ne 'Security 4624 type 7') {
+        Return $false
+    }
+
+    ForEach ($CandidateEvent in @($ActivityEvents)) {
+        If (
+            $CandidateEvent.Activity -eq 'session reconnect' -and
+            [Math]::Abs(($CandidateEvent.TimeCreated - $ActivityEvent.TimeCreated).TotalSeconds) -le 5
+        ) {
+            Return $true
+        }
+    }
+
+    Return $false
+}
+
 Function Get-PossibleUseWindow {
     Param(
         [AllowNull()]
         [object[]]$ActivityEvents
     )
 
-    $OpenWindows = @{}
+    $OpenWindow = $null
     $UseWindows = New-Object System.Collections.Generic.List[object]
     $OpeningActivities = @('logon', 'unlock', 'remote logon', 'session reconnect', 'screensaver dismiss')
     $ImpliedClosureDescriptions = @{
@@ -600,19 +652,19 @@ Function Get-PossibleUseWindow {
         'screensaver dismiss' = 'implied prior screensaver before'
     }
 
-    ForEach ($ActivityEvent in (@($ActivityEvents) | Where-Object { $null -ne $_ } | Sort-Object -Property TimeCreated)) {
+    $OrderedActivityEvents = @($ActivityEvents | Where-Object { $null -ne $_ } | Sort-Object -Property TimeCreated)
+
+    ForEach ($ActivityEvent in $OrderedActivityEvents) {
         $User = [string]$ActivityEvent.User
-        $UserKey = [string]$ActivityEvent.UserKey
         $Activity = [string]$ActivityEvent.Activity
         $Source = [string]$ActivityEvent.Source
 
-        If ([string]::IsNullOrWhiteSpace($UserKey)) {
+        If (Test-RedundantSessionReconnectUnlock -ActivityEvent $ActivityEvent -ActivityEvents $OrderedActivityEvents) {
-            $UserKey = Get-UserLogonActivityKey -Sid $null -User $User
+            Continue
         }
 
-        If ($Activity -in @('sleep', 'shutdown', 'restart')) {
+        If ($Activity -in @('logoff', 'lock', 'session disconnect', 'sleep', 'shutdown', 'restart')) {
-            ForEach ($OpenUserKey in @($OpenWindows.Keys)) {
+            If ($null -ne $OpenWindow) {
-                $OpenWindow = $OpenWindows[$OpenUserKey]
                 $UseWindows.Add([PSCustomObject]@{
                     StartTime = $OpenWindow.StartTime
                     Start = $OpenWindow.StartTime.ToString('yyyy-MM-dd HH:mm:ss')
@@ -621,7 +673,7 @@ Function Get-PossibleUseWindow {
                     StartedBy = $OpenWindow.StartedBy
                     EndedBy = "${Activity} / ${Source}"
                 }) | Out-Null
-                $OpenWindows.Remove($OpenUserKey)
+                $OpenWindow = $null
             }
 
             Continue
@@ -632,8 +684,7 @@ Function Get-PossibleUseWindow {
         }
 
         If ($Activity -in $OpeningActivities) {
-            If ($OpenWindows.ContainsKey($UserKey) -and $ImpliedClosureDescriptions.ContainsKey($Activity)) {
+            If ($null -ne $OpenWindow -and $ImpliedClosureDescriptions.ContainsKey($Activity)) {
-                $OpenWindow = $OpenWindows[$UserKey]
                 $UseWindows.Add([PSCustomObject]@{
                     StartTime = $OpenWindow.StartTime
                     Start = $OpenWindow.StartTime.ToString('yyyy-MM-dd HH:mm:ss')
@@ -642,35 +693,20 @@ Function Get-PossibleUseWindow {
                     StartedBy = $OpenWindow.StartedBy
                     EndedBy = "$($ImpliedClosureDescriptions[$Activity]) ${Activity} / ${Source}"
                 }) | Out-Null
-                $OpenWindows.Remove($UserKey)
+                $OpenWindow = $null
             }
 
-            If (-not $OpenWindows.ContainsKey($UserKey)) {
+            If ($null -eq $OpenWindow) {
-                $OpenWindows[$UserKey] = [PSCustomObject]@{
+                $OpenWindow = [PSCustomObject]@{
                     StartTime = $ActivityEvent.TimeCreated
                     User = $User
                     StartedBy = "${Activity} / ${Source}"
                 }
             }
         }
-        ElseIf ($Activity -in @('logoff', 'lock', 'session disconnect')) {
-            If ($OpenWindows.ContainsKey($UserKey)) {
-                $OpenWindow = $OpenWindows[$UserKey]
-                $UseWindows.Add([PSCustomObject]@{
-                    StartTime = $OpenWindow.StartTime
-                    Start = $OpenWindow.StartTime.ToString('yyyy-MM-dd HH:mm:ss')
-                    End = $ActivityEvent.TimeCreated.ToString('yyyy-MM-dd HH:mm:ss')
-                    User = $OpenWindow.User
-                    StartedBy = $OpenWindow.StartedBy
-                    EndedBy = "${Activity} / ${Source}"
-                }) | Out-Null
-                $OpenWindows.Remove($UserKey)
-            }
-        }
     }
 
-    ForEach ($OpenUserKey in @($OpenWindows.Keys)) {
+    If ($null -ne $OpenWindow) {
-        $OpenWindow = $OpenWindows[$OpenUserKey]
         $UseWindows.Add([PSCustomObject]@{
             StartTime = $OpenWindow.StartTime
             Start = $OpenWindow.StartTime.ToString('yyyy-MM-dd HH:mm:ss')
@@ -769,7 +805,7 @@ Try {
     }
 }
 Catch {
-    Write-Error $_.Exception.Message
+    Write-Error (Get-UserLogonActivityErrorMessage -ErrorRecord $_ -FallbackMessage 'Unable to resolve the activity date range.')
     Exit 1
 }
 
@@ -817,4 +853,11 @@ ForEach ($PowerFilter in $PowerFilters) {
 
 $OutputEvents = @(Get-UniqueUserLogonActivity -ActivityEvents $ActivityEvents | Sort-Object -Property TimeCreated)
 Write-UserLogonActivityOutput -ActivityEvents $OutputEvents
-Write-PossibleUseWindowOutput -ActivityEvents $OutputEvents
+Try {
+    Write-PossibleUseWindowOutput -ActivityEvents $OutputEvents
+}
+Catch {
+    $PossibleUseWindowError = Get-UserLogonActivityErrorMessage -ErrorRecord $_ -FallbackMessage 'Unable to infer possible use windows.'
+    Write-Output ''
+    Write-Output "Possible use windows inferred from returned events: unavailable. ${PossibleUseWindowError}"
+}