In a previous post I’ve been looking at how to use file screening to help block CryptoLocker. File screening is a great feature of Windows Server 2012 but the set up can be a pain. With this in mind this is a handy script which will make all the configuration changes for you.
Hosted over at GitHub a user called M-Dwyer has posted an awesome script called CryptoBlocker to take care of the entire process for you – from installing File Screening through to adding shares and configuring the file extension restrictions.
I’ve included a copy below but I would encourage you to have a read over the readme.md file hosted at GitHub. Just copy the file to a powershell script and then run it on your 2012 server.
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# DeployCryptoBlocker.ps1 # # This script performs the following actions: # 1) Checks for network shares # 2) Install File Server Resource Manager (FSRM) if missing # 3) Creates Batch and PowerShell scripts used by FSRM # 4) Creates a File Group within FSRM containing malicious extensions to screen on # 5) Creates a File Screen Template utilising this File Group, with an Event notification and Command notification # to run the scripts created in Step 3) # 6) Creates File Screens utilising this template for each drive containing network shares ################################ Functions ################################ Function PurgeNonAdminDirectoryPermissions([string] $directory) { $acl = Get-Acl $directory if ($acl.AreAccessRulesProtected) { $acl.Access | % { $acl.PurgeAccessRules($_.IdentityReference) } } else { $acl.SetAccessRuleProtection($true, $true) } $ar = New-Object System.Security.AccessControl.FileSystemAccessRule("SYSTEM","FullControl","Allow") $acl.AddAccessRule($ar) $ar = $ar = New-Object System.Security.AccessControl.FileSystemAccessRule("BUILTIN\Administrators","FullControl","Allow") $acl.AddAccessRule($ar) Set-Acl -AclObject $acl -Path $directory } ################################ Functions ################################ # Add to all drives $drivesContainingShares = Get-WmiObject Win32_Share | Select Name,Path,Type | Where-Object { $_.Type -eq 0 } | Select -ExpandProperty Path | % { "$((Get-Item -ErrorAction SilentlyContinue $_).Root)" } | Select -Unique if ($drivesContainingShares -eq $null -or $drivesContainingShares.Length -eq 0) { Write-Host "No drives containing shares were found. Exiting.." exit } Write-Host "The following shares needing to be protected: $($drivesContainingShares -Join ",")" $majorVer = [System.Environment]::OSVersion.Version.Major $minorVer = [System.Environment]::OSVersion.Version.Minor Write-Host "Checking File Server Resource Manager.." Import-Module ServerManager if ($majorVer -ge 6) { $checkFSRM = Get-WindowsFeature -Name FS-Resource-Manager if ($minorVer -ge 2 -and $checkFSRM.Installed -ne "True") { # Server 2012 Write-Host "FSRM not found.. Installing (2012).." Install-WindowsFeature -Name FS-Resource-Manager -IncludeManagementTools } elseif ($minorVer -ge 1 -and $checkFSRM.Installed -ne "True") { # Server 2008 R2 Write-Host "FSRM not found.. Installing (2008 R2).." Add-WindowsFeature FS-FileServer, FS-Resource-Manager } elseif ($checkFSRM.Installed -ne "True") { # Server 2008 Write-Host "FSRM not found.. Installing (2008).." &servermanagercmd -Install FS-FileServer FS-Resource-Manager } } else { # Assume Server 2003 Write-Host "Other version of Windows detected! Quitting.." return } $fileGroupName = "CryptoBlockerGroup" $fileTemplateName = "CryptoBlockerTemplate" $fileScreenName = "CryptoBlockerScreen" $monitoredExtensions = @( "*.cryptotorlocker*", "*.encrypted", "*.frtrss", "*.vault", "*want your files back.*", "confirmation.key", "cryptolocker.*", "*decrypt_instruct*", "enc_files.txt", "*help_decrypt*", "help_restore*.*", "how to decrypt*", "how_to_decrypt*", "how_to_recover*", "howtodecrypt*", "install_tor*.*", "last_chance.txt", "recovery_file.txt", "recovery_key.txt", "vault.hta", "vault.key", "vault.txt", "HOW_TO_RECOVER_FILES.*", "HELP_YOUR_FILES*", "*RECOVER_INSTRUCTIONS*", "*.micro", "*.locky" ) $scriptFilename = "C:\FSRMScripts\KillUserSession.ps1" $batchFilename = "C:\FSRMScripts\KillUserSession.bat" $eventConfFilename = "$env:Temp\cryptoblocker-eventnotify.txt" $cmdConfFilename = "$env:Temp\cryptoblocker-cmdnotify.txt" $scriptConf = @' param([string] $DomainUser) Function DenySharePermission ([string] $ShareName, [string] $DomainUser) { $domainUserSplit = $DomainUser.Split("\") $trusteeClass = [wmiclass] "ROOT\CIMV2:Win32_Trustee" $trustee = $trusteeClass.CreateInstance() $trustee.Domain = $domainUserSplit[0] $trustee.Name = $domainUserSplit[1] $aceClass = [wmiclass] "ROOT\CIMV2:Win32_ACE" $ace = $aceClass.CreateInstance() $ace.AccessMask = 2032127 $ace.AceType = 1 $ace.Trustee = $trustee $shss = Get-WmiObject -Class Win32_LogicalShareSecuritySetting -Filter "Name='$ShareName'" $sd = Invoke-WmiMethod -InputObject $shss -Name GetSecurityDescriptor | Select -ExpandProperty Descriptor $sclass = [wmiclass] "ROOT\CIMV2:Win32_SecurityDescriptor" $newsd = $sclass.CreateInstance() $newsd.ControlFlags = $sd.ControlFlags foreach ($oace in $sd.DACL) { $newsd.DACL += [System.Management.ManagementBaseObject] $oace } $newsd.DACL += [System.Management.ManagementBaseObject] $ace $share = Get-WmiObject -Class Win32_LogicalShareSecuritySetting -Filter "Name='$ShareName'" $setResult = $share.SetSecurityDescriptor($newsd) return $setResult.ReturnValue } # Let's try altering share permissions.. $Username = $DomainUser.Split("\")[1] $affectedShares = Get-WmiObject -Class Win32_Share | Select Name, Path, Type | Where { $_.Type -eq 0 } $affectedShares | % { Write-Host "Denying [$DomainUser] access to share [$($_.Name)].." DenySharePermission -ShareName $_.Name -DomainUser $DomainUser } Write-Host $affectedShares '@ $batchConf = @" @echo off powershell.exe -ExecutionPolicy Bypass -File "$scriptFilename" -DomainUser %1 "@ $scriptDirectory = Split-Path -Parent $scriptFilename $batchDirectory = Split-Path -Parent $batchFilename if (-not (Test-Path $scriptDirectory)) { Write-Host "Script directory [$scriptDirectory] not found. Creating.." New-Item -Path $scriptDirectory -ItemType Directory } if (-not (Test-Path $batchDirectory)) { Write-Host "Batch directory [$batchDirectory] not found. Creating.." New-Item -Path $batchDirectory -ItemType Directory } # FSRM stipulates that the command directories/files can only be accessible by SYSTEM or Administrators # As a result, we lock down permissions for SYSTEM and local admin only Write-Host "Purging Non-Admin NTFS permissions on script directory [$scriptDirectory].." PurgeNonAdminDirectoryPermissions($scriptDirectory) Write-Host "Purging Non-Admin NTFS permissions on batch directory [$batchDirectory].." PurgeNonAdminDirectoryPermissions($batchDirectory) Write-Host "Writing defensive PowerShell script to location [$scriptFilename].." $scriptConf | Out-File -Encoding ASCII $scriptFilename Write-Host "Writing batch script launcher to location [$batchFilename].." $batchConf | Out-File -Encoding ASCII $batchFilename $eventConf = @" Notification=E RunLimitInterval=0 EventType=Warning Message=User [Source Io Owner] attempted to save [Source File Path] to [File Screen Path] on the [Server] server. This file is in the [Violated File Group] file group, which is not permitted on the server. An attempt has been made at blocking this user. "@ $cmdConf = @" Notification=C RunLimitInterval=0 Command=$batchFilename Arguments=[Source Io Owner] MonitorCommand=Enable Account=LocalSystem "@ Write-Host "Writing temporary FSRM Event Viewer configuration to location [$eventConfFilename].." $eventConf | Out-File $eventConfFilename Write-Host "Writing temporary FSRM Command configuration to location [$cmdConfFilename].." $cmdConf | Out-File $cmdConfFilename Write-Host "Adding/replacing File Group [$fileGroupName] with monitored file [$($monitoredExtensions -Join ",")].." &filescrn.exe filegroup Delete /Filegroup:$fileGroupName /Quiet &filescrn.exe Filegroup Add "/Filegroup:$fileGroupName" "/Members:$($monitoredExtensions -Join "|")" Write-Host "Adding/replacing File Screen Template [$fileTemplateName] with Event Notification [$eventConfFilename] and Command Notification [$cmdConfFilename].." &filescrn.exe Template Delete /Template:$fileTemplateName /Quiet &filescrn.exe Template Add "/Template:$fileTemplateName" "/Add-Filegroup:$fileGroupName" "/Add-Notification:E,$eventConfFilename" "/Add-Notification:C,$cmdConfFilename" /Type:Passive Write-Host "Adding/replacing File Screens.." $drivesContainingShares | % { Write-Host "`tAdding/replacing File Screen for [$_] with Source Template [$fileTemplateName].." &filescrn.exe Screen Delete "/Path:$_" /Quiet &filescrn.exe Screen Add "/Path:$_" "/SourceTemplate:$fileTemplateName" } Write-Host "Removing temporary FSRM Event Viewer configuration file [$eventConfFilename].." Write-Host "Removing temporary FSRM Event Viewer configuration file [$cmdConfFilename].." Remove-Item $eventConfFilename Remove-Item $cmdConfFilename |
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