Response Server

A Model Context Protocol (MCP) server that enables agentic SecOps using orchestrators like VS Code with GitHub Copilot to execute Microsoft Defender XDR response actions. Deployed to Azure Container Apps for secure, authenticated, cloud-based access.

Overview

This MCP server exposes Microsoft Defender XDR capabilities as tools for agentic SecOps workflows. Security analysts use natural language through orchestrators like GitHub Copilot to manage incidents, isolate compromised devices, run antivirus scans, collect forensic packages, and execute incident response actions.

Showcase - https://markolauren.github.io/ResponseMCP/response-mcp-showcase.html

Works in Tandem with Sentinel MCP

This Response MCP server works in tandem with the Sentinel MCP server to provide a complete agentic SecOps workflow:

• Sentinel MCP: Data exploration and threat triage

  • Query security logs with KQL
  • Investigate alerts and run hunting queries
  • Analyze attack patterns and indicators
  • Entity analysis

• Response MCP (this server): Incident response and remediation

  • Execute device response actions (isolate, restrict, quarantine)
  • Take identity response actions (disable accounts, reset passwords)
  • Manage incidents (classify, assign, comment)

Together, they enable end-to-end incident response: from detection and triage to containment and remediation, all through natural language interactions and agentic orchestration.

Example interactions:

• "Check the status of device WORKSTATION-01"
• "Isolate the compromised laptop immediately"
• "Run a full antivirus scan on the server"
• "Show me recent response actions on this device"

Architecture

┌─────────────────┐                ┌──────────────────────┐
│   VS Code +     │────SSE────────▶│  Azure Container App │
│  GitHub Copilot │  X-API-Key     │  (Response MCP)      │
└─────────────────┘  Authentication└──────────────────────┘
                                             │
                                             │ Client Credentials
                                             │ (Service Principal)
                                             │
                         ┌───────────────────┴───────────────────┐
                         ▼                                       ▼
          ┌─────────────────────────────┐     ┌─────────────────────────────┐
          │  Microsoft Defender         │     │  Microsoft Graph API        │
          │  for Endpoint               │     │  - Incident management      │
          │  - Device response actions  │     │  - Identity actions (MDI)   │
          │  - Investigation packages   │     └─────────────────────────────┘
          └─────────────────────────────┘

SSE (Server-Sent Events): A web standard that maintains a persistent HTTP connection, allowing the MCP server to stream real-time responses back to the AI assistant.

Available Tools

Device Response Actions (Defender for Endpoint)

Tool	Description
echo	Test server connectivity
get_machine_by_name	Find device by hostname
get_machine_actions	List response action history
isolate_device	Isolate device from network
release_device	Release device from isolation
run_antivirus_scan	Initiate Quick or Full AV scan
stop_and_quarantine	Stop process and quarantine file
restrict_code_execution	Block unsigned applications
remove_code_restriction	Remove code restrictions
collect_investigation_package	Collect forensic data
get_investigation_package_uri	Get download URL for investigation package
isolate_multiple	Bulk isolate multiple devices

Identity Response Actions (Defender for Identity & Entra ID)

Tool	Description	Provider
disable_ad_account	Disable Active Directory account	Active Directory
enable_ad_account	Re-enable Active Directory account	Active Directory
force_ad_password_reset	Force user to change password at next logon	Active Directory
revoke_entra_sessions	Revoke all Entra ID sessions and refresh tokens	Entra ID
confirm_user_compromised	Mark user as compromised in Identity Protection	Entra ID
confirm_user_safe	Dismiss user risk (mark as safe) in Identity Protection	Entra ID

Incident Management

Tool	Description
update_incident_status	Mark incident as active/resolved
assign_incident	Assign incident to analyst
classify_incident	Set classification (TP/FP) and determination
add_incident_tags	Add custom tags for categorization
add_incident_comment	Add investigation comments

Prerequisites

1. Entra ID App Registration

Steps:

1. Navigate to Azure Portal > Entra ID > App Registrations > New registration
   • Name: Response MCP Server (or your preferred name)
   • Supported account types: Accounts in this organizational directory only
   • Click Register
2. Save these values (needed for deployment):
   • Application (client) ID
   • Directory (tenant) ID
3. Create a client secret:
   • Go to Certificates & secrets > New client secret
   • Description: Response MCP Secret
   • Expires: Choose expiration period (e.g., 12 months)
   • Click Add
   • Copy the secret value immediately (shown only once)
4. Add API permissions:
   • Go to API permissions > Add a permission
   • Add the permissions listed below
   • Grant admin consent for all permissions

Required Permissions

WindowsDefenderATP (Defender for Endpoint)

Permission	Type	Description
Machine.ReadWrite.All	Application	Read machine actions and get investigation package URIs
Machine.Isolate	Application	Isolate/release machines
Machine.Scan	Application	Run antivirus scans
Machine.StopAndQuarantine	Application	Stop and quarantine files
Machine.RestrictExecution	Application	Restrict/unrestrict code execution
Machine.CollectForensics	Application	Collect investigation packages

Microsoft Graph API

Permission	Type	Description
SecurityAlert.ReadWrite.All	Application	Read and update security alerts
SecurityIdentitiesAccount.Read.All	Application	Read identity accounts from MDI
SecurityIdentitiesActions.ReadWrite.All	Application	Invoke actions on identity accounts
SecurityIncident.ReadWrite.All	Application	Read and update security incidents
User.Read.All	Application	Resolve UPNs to user IDs
User.RevokeSessions.All	Application	Revoke user sessions
IdentityRiskyUser.ReadWrite.All	Application	Mark users as compromised in Identity Protection

2. Azure Subscription

For deploying to Azure Container Apps.

Azure Infrastructure:

┌─────────────────────────────────────────────────────────────┐
│  Resource Group: response-mcp-rg                            │
│                                                             │
│  ┌────────────────────────────────────────────────────┐     │
│  │  Container Apps Environment                        │     │
│  │  - Managed Kubernetes infrastructure               │     │
│  │  - Auto-scaling (min: 0, max: 3 replicas)          │     │
│  │                                                    │     │
│  │  ┌──────────────────────────────────────────┐      │     │
│  │  │  Container App: response-mcp             │      │     │
│  │  │  - SSE endpoint on port 8000             │      │     │
│  │  │  - API key authentication                │      │     │
│  │  │  - Environment secrets (Defender creds)  │      │     │
│  │  │  - HTTPS ingress                         │      │     │
│  │  └──────────────────────────────────────────┘      │     │
│  │                                                    │     │
│  └────────────────────────────────────────────────────┘     │
│                                                             │
│  ┌────────────────────────────────────────────────────┐     │
│  │  Azure Container Registry (Basic)                  │     │
│  │  - Stores Docker images                            │     │
│  │  - ACR Tasks for cloud builds                      │     │
│  └────────────────────────────────────────────────────┘     │
│                                                             │
│  ┌────────────────────────────────────────────────────┐     │
│  │  Log Analytics Workspace                           │     │
│  │  - Container App logs                              │     │
│  │  - Request/response tracing                        │     │
│  │  - 30-day retention                                │     │
│  └────────────────────────────────────────────────────┘     │
│                                                             │
└─────────────────────────────────────────────────────────────┘

Deployment to Azure Container Apps

Prerequisites

• Azure CLI (v2.20.0+) - Install or winget install Microsoft.AzureCLI
• Bicep - Included with Azure CLI, upgrade with az bicep upgrade if needed
• Authenticated - Run az login before deployment
• Entra ID App Registration with required API permissions (see Prerequisites section above)
• Azure subscription with permission to create resources

Step 1: Deploy Infrastructure (One-Time Setup)

Deploy the Azure infrastructure (Container Registry, Log Analytics, Container App environment):

.\infra\deploy-infrastructure.ps1 `
  -ResourceGroup "response-mcp-rg" `
  -Location "westeurope" `
  -DefenderClientId "your-app-client-id" `
  -DefenderClientSecret (ConvertTo-SecureString "your-client-secret" -AsPlainText -Force) `
  -DefenderTenantId "your-tenant-id"

What happens:

• Creates resource group, Azure Container Registry, Log Analytics workspace
• Deploys Container App with managed environment and auto-scaling
• Auto-generates MCP API key and configures it as a secret
• Outputs SSE endpoint URL and displays the API key (save it - won't be shown again!)

Optional: Provide your own API key:

-McpApiKey (ConvertTo-SecureString "your-custom-api-key" -AsPlainText -Force)

Step 2: Build and Deploy Container

Build the Docker image and deploy it to the Container App:

.\infra\deploy-container.ps1 -ResourceGroup "response-mcp-rg"

What happens:

• Builds Docker image in Azure Container Registry (cloud build - no local Docker required)
• Uploads source code to Azure
• Builds container image on Azure infrastructure
• Creates new revision with timestamp
• Updates Container App and activates the new revision

Note: Docker Desktop is not required - the build happens entirely in Azure using ACR Tasks.

For subsequent updates: Just run Step 2 again to deploy code changes.

Step 3: Configure VS Code

Add to your MCP settings:

{
  "mcpServers": {
    "response-mcp": {
      "type": "sse",
      "url": "https://your-app.azurecontainerapps.io/sse",
      "headers": {
        "X-API-Key": "<API-KEY-FROM-STEP-1>"
      }
    }
  }
}

Replace the URL and API key with values from Step 1 output.

Security Hardening: IP Allowlist (Recommended)

Restrict access to your Container App from specific IP addresses:

Allow a single IP:

az containerapp ingress access-restriction set `
  --name <your-container-app-name> `
  --resource-group response-mcp-rg `
  --rule-name "AllowMyIP" `
  --action Allow `
  --ip-address "203.0.113.42/32" `
  --description "My workstation"

Allow multiple IPs or ranges:

# Add office network
az containerapp ingress access-restriction set `
  --name <your-container-app-name> `
  --resource-group response-mcp-rg `
  --rule-name "AllowOffice" `
  --action Allow `
  --ip-address "203.0.113.0/24" `
  --description "Office network"

# Add VPN endpoint
az containerapp ingress access-restriction set `
  --name <your-container-app-name> `
  --resource-group response-mcp-rg `
  --rule-name "AllowVPN" `
  --action Allow `
  --ip-address "198.51.100.10/32" `
  --description "VPN gateway"

List current rules:

az containerapp ingress access-restriction list `
  --name <your-container-app-name> `
  --resource-group response-mcp-rg `
  -o table

Remove a rule:

az containerapp ingress access-restriction remove `
  --name <your-container-app-name> `
  --resource-group response-mcp-rg `
  --rule-name "AllowMyIP"

Note: IP restrictions are evaluated in order. Ensure you don't lock yourself out - test from allowed IPs before removing unrestricted access.

Security Considerations

Layer	Protection
Transport	HTTPS/TLS encryption
Authentication	API key in X-API-Key header
Network	IP allowlist on Container App (standard)
Network (Advanced)	VNet integration + Private Link/VPN (optional)
Secrets	Stored in Azure Container App secrets
Defender API	Service principal with least privilege

Standard Security (Current Deployment):

• Public endpoint with IP allowlist restrictions
• API key authentication
• HTTPS/TLS encryption
• Suitable for most organizations

Advanced Security (VNet Deployment):

For organizations requiring private network access, deploy the Container App into a VNet:

Benefits:

• Private-only access (no public internet exposure)
• Access via VPN Gateway, ExpressRoute, or Azure Bastion
• Network Security Groups (NSGs) and firewall rules
• Compliance with strict network isolation policies

Requirements:

• Custom VNet with delegated subnet for Container Apps
• VPN Gateway (~$140/month) or ExpressRoute for remote access
• Container Apps Environment with VNet integration (internal: true)
• Higher base costs (~$200+/month for workload profiles)

When to use:

• Corporate policy requires all traffic through VPN/ExpressRoute
• No public internet endpoints allowed
• Need to access private Azure services (SQL Database with private endpoints)
• Compliance requirements mandate network isolation

Not recommended if:

• Accessing from individual analyst workstations (IP allowlist is simpler)
• Cost-sensitive environments
• Standard internet connectivity is acceptable

See Azure Container Apps VNet integration for implementation details.

Recommendations:

• Rotate API keys regularly
• Use IP allowlisting for production environments (easiest)
• Consider VNet deployment only if required by policy/compliance
• Monitor Container App logs for suspicious activity
• Grant only required Defender API permissions
• Rotate client secrets regularly
• Never commit API keys to source control

Cost Estimate

Estimated monthly Azure costs: ~$12-18/month for typical usage (few analysts, business hours only). Scale-to-zero enabled to minimize idle costs. Costs increase with 24/7 operations (~$30-40/month) or higher log retention.

Troubleshooting

Connection refused:

• Check Container App is running: az containerapp show --name your-app -g your-rg
• Verify network connectivity to Azure

401 Unauthorized:

• Verify your API key is correct
• Check the X-API-Key header is being sent
• Ensure MCP_API_KEY is set in Container App environment

Defender API errors:

• Verify app registration permissions and admin consent
• Check client secret hasn't expired
• Ensure service principal has required Defender API permissions

License

MIT