Device Isolation

Pre-Incident Preparation

Environment Familiarisation

Get-CimInstance Win32_OperatingSystem | Select-Object @{N='Name';E={$_.CSName}},@{N='OS';E={$_.Caption}},@{N='Version';E={$_.Version}},@{N='Build';E={$_.BuildNumber}},@{N='InstallDate';E={$_.InstallDate}},@{N='LastBoot';E={$_.LastBootUpTime}},@{N='FreeMemoryMB';E={[math]::Round($_.FreePhysicalMemory/1024,2)}} | Export-Csv "C:\Inventory\device_$(Get-Date -Format 'yyyyMMdd_HHmmss').csv" -NoTypeInformation

Get-CimInstance Win32_NetworkAdapterConfiguration -Filter "IPEnabled = TRUE" | Select-Object @{N='Adapter';E={$_.Description}},@{N='IPAddress';E={($_.IPAddress -join ', ')}},@{N='Subnet';E={($_.IPSubnet -join ', ')}},@{N='Gateway';E={($_.DefaultIPGateway -join ', ')}},@{N='MAC';E={$_.MACAddress}},@{N='DHCP';E={$_.DHCPEnabled}},@{N='DNSServers';E={($_.DNSServerSearchOrder -join ', ')}} | Export-Csv "C:\Inventory\ip_details_$(Get-Date -Format 'yyyyMMdd_HHmmss').csv" -NoTypeInformation

DeviceNetworkEvents
| where TimeGenerated > ago(30d)
| summarize ConnectedIPs = make_set(RemoteIP), Protocols = make_set(Protocol), EventCount = count() by DeviceName, LocalIP
| project DeviceName, LocalIP, ConnectedIPs, Protocols, EventCount

DeviceNetworkEvents
| where TimeGenerated > ago(30d)
| summarize ConnectedIPs = make_set(RemoteIP), Protocols = make_set(Protocol), ConnectionCount = count() by DeviceName, LocalIP
| project DeviceName, LocalIP, ConnectedIPs, Protocols, ConnectionCount

Incident Detection and Initial Assessment

Detection Triggers

SecurityEvent
| where EventID in (4624, 4625, 4672, 4688) // Common security-related Event IDs
| project TimeGenerated, Account, EventID, Activity, Computer, IpAddress
| order by TimeGenerated desc

index=windows sourcetype="WinEventLog:Security" EventCode IN (4624, 4625, 4672, 4688)
| table _time, user, EventCode, action, host, src_ip
| sort - _time

Scope Assessment

DeviceProcessEvents
| where FileName == "svch0st.exe"
| summarize AffectedHosts = dcount(DeviceName), FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated), ProcessCount = count(), AffectedHostsList = make_set(DeviceName) by FileName

index=edr process_name="svch0st.exe"
| stats dc(host) as AffectedHosts, earliest(_time) as FirstSeen, latest(_time) as LastSeen, count as ProcessCount, values(host) as AffectedHostsList by process_name

Containment (Short-Term)

Network-Level Containment

Isolate a Device Using the Defender Live Response Console

Initiate Live Response Session
Click Go Hunt → Initiate Live Response session.
Isolate the Device
In the Live Response console, enter:
```
isolate
```
To verify isolation status:
```
isolationstatus
```
(Optional) Release Isolation
To reconnect the device:
```
release
```

Steps to Isolate a Device Using Live Response in Microsoft Defender

Start a Live Response Session:
- On the device’s page, look for the ellipsis (...) in the top-right corner of the Response Actions section.
- Select Initiate Live Response Session (you might need to expand "Advanced actions" depending on your UI version).
- Confirm the action if prompted. Once the session starts, a command-line interface (CLI) will appear in the portal with a prompt like Connected to <DeviceName>.
Execute Commands to Isolate the Device:
- In the Live Response CLI, you’ll manually disable network connectivity to isolate the device. Since Live Response supports PowerShell, you can run a command to disable all active network adapters:
  run powershell.exe -Command "Get-NetAdapter | Where-Object { $_.Status -eq 'Up' } | Disable-NetAdapter -Confirm:$false"
  - What this does:
    Get-NetAdapter: Lists all network adapters on the device.
    Where-Object { $_.Status -eq 'Up' }: Filters for only active adapters.
    Disable-NetAdapter -Confirm:$false: Disables them without prompting.
  - Result: The device loses network connectivity, but Defender’s cloud communication typically persists due to its low-level sensor exceptions.
Verify the Isolation:
- Check the network adapter status to confirm:
  run powershell.exe -Command "Get-NetAdapter | Select-Object Name, Status | Out-File C:\temp\netstatus.txt"
  - This saves the adapter status to a file on the device.
- Retrieve the file to review:
  getfile C:\temp\netstatus.txt
  - The output should show all adapters as "Disabled" (except possibly virtual adapters used by Defender).
- Alternatively, test connectivity:
  run cmd.exe -Command "ping 8.8.8.8"
  - If isolated, this should fail or timeout.
End the Live Response Session:
- Once you’ve confirmed isolation, type:
  exit
  - Or click Disconnect Session in the portal UI to close the session.

Optional: Use a Pre-Uploaded ScriptFor efficiency or reusability, you can upload a PowerShell script to the Live Response library beforehand:

Go to Settings > Endpoints > Live Response > Library > Upload File.

Upload this script (e.g., isolate_device.ps1):

# Isolate device by disabling network adapters
Get-NetAdapter | Where-Object { $_.Status -eq "Up" } | Disable-NetAdapter -Confirm:$false
Write-Output "Device isolated - network adapters disabled."

In the Live Response session, run it:
```
run isolate_device.ps1
```

New-NetFirewallRule -DisplayName "BlockC2" -RemoteAddress 203.0.113.5 -Action Block

PowerShell Function: Isolate-Devicepowershell

function Isolate-Device {
    param (
        [string]$DeviceName
    )

    try {
        Invoke-Command -ComputerName $DeviceName -ScriptBlock {
            # Get all active network adapters
            $adapters = Get-NetAdapter | Where-Object { $_.Status -eq 'Up' }
            if ($adapters) {
                # Collect the names of the active adapters
                $adapterNames = $adapters | ForEach-Object { $_.Name }
                # Disable the active adapters without confirmation
                Disable-NetAdapter -Name $adapterNames -Confirm:$false -ErrorAction Stop
                # Log the isolation action in the event log
                Write-EventLog -LogName Application -Source "Windows PowerShell" -EventId 1000 -Message "Device isolated by disabling adapters: $($adapterNames -join ', ')"
            } else {
                # Log if no active adapters were found
                Write-EventLog -LogName Application -Source "Windows PowerShell" -EventId 1000 -Message "No active network adapters found to disable."
            }
        } -ErrorAction Stop
        Write-Host "Successfully isolated device: $DeviceName"
    } catch {
        Write-Error "Failed to isolate device: $DeviceName. Error: $_"
    }
}

How to Use the Script

Run the Script: Ensure you have this function loaded in your PowerShell session (e.g., save it in a .ps1 file and dot-source it, or paste it directly into your session).
Call the Function: Execute the function by providing the target device’s name, like this:powershell
```
Isolate-Device -DeviceName "TargetComputerName"
```
Replace "TargetComputerName" with the actual name of the device you want to isolate.

PowerShell Function: Enable-Devicepowershell

function Enable-Device {
    param (
        [string]$DeviceName
    )

    try {
        Invoke-Command -ComputerName $DeviceName -ScriptBlock {
            # Get all disabled network adapters
            $adapters = Get-NetAdapter | Where-Object { $_.Status -ne 'Up' }
            if ($adapters) {
                # Collect the names of the disabled adapters
                $adapterNames = $adapters | ForEach-Object { $_.Name }
                # Enable the disabled adapters without confirmation
                Enable-NetAdapter -Name $adapterNames -Confirm:$false -ErrorAction Stop
                # Log the re-enablement action in the event log
                Write-EventLog -LogName Application -Source "Windows PowerShell" -EventId 1001 -Message "Device re-enabled by enabling adapters: $($adapterNames -join ', ')"
            } else {
                # Log if no disabled adapters were found
                Write-EventLog -LogName Application -Source "Windows PowerShell" -EventId 1001 -Message "No disabled network adapters found to enable."
            }
        } -ErrorAction Stop
        Write-Host "Successfully re-enabled device: $DeviceName"
    } catch {
        Write-Error "Failed to re-enable device: $DeviceName. Error: $_"
    }
}

How to Use the Script

Load the Function: Save this script in a .ps1 file (e.g., Enable-Device.ps1) and dot-source it in your PowerShell session (. .\Enable-Device.ps1), or paste it directly into your session.
Run the Function: Execute it by providing the target device’s name:powershell
```
Enable-Device -DeviceName "TargetComputerName"
```
Replace "TargetComputerName" with the name of the device you want to re-enable.

System-Level Containment

This method assumes remote or local execution capability.

Script: Comprehensive Containment

# Check for admin privileges
if (-not ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
    Write-Warning "Run as Administrator required."
    exit
}

# Disable all active network adapters
$adapters = Get-NetAdapter | Where-Object { $_.Status -eq 'Up' }
if ($adapters) {
    $adapterNames = $adapters | ForEach-Object { $_.Name }
    Disable-NetAdapter -Name $adapterNames -Confirm:$false -ErrorAction SilentlyContinue
    Write-Host "Network adapters disabled: $adapterNames"
} else {
    Write-Host "No active adapters found."
}

# Block all outbound and inbound traffic with Windows Firewall
New-NetFirewallRule -DisplayName "Block All Outbound" -Direction Outbound -Action Block -Enabled True
New-NetFirewallRule -DisplayName "Block All Inbound" -Direction Inbound -Action Block -Enabled True
Write-Host "Firewall rules applied to block all traffic."

# Optional: Stop non-essential services (e.g., file sharing)
Stop-Service -Name "Server" -Force -ErrorAction SilentlyContinue
Stop-Service -Name "Workstation" -Force -ErrorAction SilentlyContinue
Write-Host "Stopped non-essential services."

How It Works:

Network Adapters: Disables all active adapters, cutting physical network access.
Firewall Rules: Blocks all inbound and outbound traffic as a secondary layer, even if adapters are re-enabled.
Services: Stops services like "Server" (SMB sharing) and "Workstation" (SMB client) to limit local network interactions.

Usage:

Run locally: Save as Contain-System.ps1 and execute in an elevated PowerShell session.
Run remotely: Use Invoke-Command -ComputerName "TargetDevice" -ScriptBlock { <script above> } if remoting is still available.

Reversal:

# Re-enable adapters
Enable-NetAdapter -Name (Get-NetAdapter | Where-Object { $_.Status -ne 'Up' } | ForEach-Object { $_.Name }) -Confirm:$false
# Remove firewall rules
Remove-NetFirewallRule -DisplayName "Block All Outbound"
Remove-NetFirewallRule -DisplayName "Block All Inbound"
# Restart services
Start-Service -Name "Server"
Start-Service -Name "Workstation"

3. Windows Firewall for Network ContainmentIf physical adapter control isn’t desired, you can use the Windows Firewall to block all network traffic at the system level.

Steps (via PowerShell):

# Block all traffic
New-NetFirewallRule -DisplayName "Containment Outbound" -Direction Outbound -Action Block -Enabled True
New-NetFirewallRule -DisplayName "Containment Inbound" -Direction Inbound -Action Block -Enabled True

Why This Works:

Firewall rules apply system-wide, preventing all network communication regardless of adapter state.
Easier to reverse than disabling adapters, as it doesn’t require physical access if remoting is lost.

Reversal:

Remove-NetFirewallRule -DisplayName "Containment Outbound"
Remove-NetFirewallRule -DisplayName "Containment Inbound"

4. Defender Live Response for Containment

You can manually execute commands to isolate a device.

Steps:

Start Live Response:
Go to the device page in the Defender portal and select Initiate Live Response Session.

Disable Adapters:

Run:

run cmd.exe -Command "for /f \"skip=1\" %%a in ('wmic path Win32_NetworkAdapter where \"DeviceEnabled=true\" get DeviceID') do (wmic path Win32_NetworkAdapter where \"DeviceID='%%a'\" call Disable)"

Verify:

Check status:

run cmd.exe -Command "wmic path Win32_NetworkAdapter get DeviceID, DeviceEnabled"

Reversal:

Re-enable adapters:

run cmd.exe -Command "for /f \"skip=1\" %%a in ('wmic path Win32_NetworkAdapter get DeviceID') do (wmic path Win32_NetworkAdapter where \"DeviceID='%%a'\" call Enable)"

Command modifies a specific registry key on a Windows system to disable remote desktop (RDP) connections.

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server" -Name "fDenyTSConnections" -Value 1

VerificationTo confirm the change:

Get-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server" -Name "fDenyTSConnections"

Look for fDenyTSConnections : 1 in the output.

Reversal

To re-enable Remote Desktop:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Terminal Server" -Name "fDenyTSConnections" -Value 0

To fully stop the service:

Stop-Service -Name TermService -Force

Enterprise-Wide Checks

Basic Check:

DeviceFileEvents
| where FileName contains "ransom"

DeviceFileEvents
| where FileName has "ransom" or InitiatingProcessFileName has "ransom"
| where ActionType in ("FileCreated", "FileModified", "FileDeleted", "FileRenamed")
| extend FilePath = tolower(strcat(FolderPath, "\\", FileName))
| summarize 
    EventCount = count(),
    FirstSeen = min(TimeGenerated),
    LastSeen = max(TimeGenerated),
    AffectedDevices = dcount(DeviceName),
    FilePaths = make_set(FilePath),
    InitiatingProcesses = make_set(InitiatingProcessFileName)
    by FileName, ActionType
| where EventCount > 1 or AffectedDevices > 1
| order by LastSeen desc

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Last updated 3 months ago