deploying-edr-agent-with-crowdstrike

Deploying EDR Agent with CrowdStrike

When to Use

Use this skill when:

• Deploying CrowdStrike Falcon sensors to Windows, macOS, or Linux endpoints
• Configuring Falcon prevention and detection policies for different endpoint groups
• Integrating CrowdStrike telemetry with SIEM (Splunk, Elastic, Sentinel) for correlated detection
• Troubleshooting sensor connectivity, performance, or detection issues

Do not use this skill for deploying other EDR solutions (Carbon Black, SentinelOne) or for Falcon cloud workload protection (use cloud-specific deployment guides).

Prerequisites

• CrowdStrike Falcon console access with Falcon Administrator role
• Customer ID (CID) and Falcon sensor installer package
• Administrative/root access on target endpoints
• Network access: endpoints must reach CrowdStrike cloud (ts01-b.cloudsink.net on port 443)
• Deployment tool: SCCM, Intune, GPO, Ansible, or manual installation

Workflow

Step 1: Obtain Falcon Sensor Installer and CID

1. Log into Falcon Console: https://falcon.crowdstrike.com
2. Navigate: Host setup and management → Sensor downloads
3. Download the appropriate installer:
   - Windows: WindowsSensor_<version>.exe
   - macOS: FalconSensorMacOS_<version>.pkg
   - Linux: falcon-sensor_<version>_amd64.deb / .rpm
4. Copy the Customer ID (CID) from the Sensor downloads page
   - CID format: <32-char-hex>-<2-char-checksum>

Step 2: Deploy Falcon Sensor - Windows

Silent installation via command line:

WindowsSensor_7.18.17106.exe /install /quiet /norestart CID=<YOUR_CID>

SCCM deployment:

1. Create an Application in SCCM
2. Deployment type: Script Installer
3. Install command: WindowsSensor_7.18.17106.exe /install /quiet /norestart CID=<CID>
4. Detection method: Registry key exists
   - HKLM\SYSTEM\CrowdStrike\{9b03c1d9-3138-44ed-9fae-d9f4c034b88d}\{16e0423f-7058-48c9-a204-725362b67639}\Default
5. Deploy to target collection
6. Deployment purpose: Required (for mandatory installation)

Microsoft Intune deployment:

1. Navigate: Devices → Windows → Configuration profiles
2. Create Win32 app deployment
3. Upload .intunewin package (wrapped sensor installer)
4. Install command: WindowsSensor_7.18.17106.exe /install /quiet /norestart CID=<CID>
5. Detection rule: File exists C:\Windows\System32\drivers\CrowdStrike\csagent.sys
6. Assign to device group

GPO deployment:

# Create startup script that checks for existing installation
$sensorPath = "C:\Windows\System32\drivers\CrowdStrike\csagent.sys"
if (-not (Test-Path $sensorPath)) {
    Start-Process -FilePath "\\fileserver\CrowdStrike\WindowsSensor.exe" `
      -ArgumentList "/install /quiet /norestart CID=<CID>" -Wait
}

Step 3: Deploy Falcon Sensor - Linux

# Debian/Ubuntu
sudo dpkg -i falcon-sensor_7.18.0-17106_amd64.deb
sudo /opt/CrowdStrike/falconctl -s -f --cid=<YOUR_CID>
sudo systemctl start falcon-sensor
sudo systemctl enable falcon-sensor

# RHEL/CentOS
sudo yum install falcon-sensor-7.18.0-17106.el8.x86_64.rpm
sudo /opt/CrowdStrike/falconctl -s -f --cid=<YOUR_CID>
sudo systemctl start falcon-sensor
sudo systemctl enable falcon-sensor

# Verify sensor is running and connected
sudo /opt/CrowdStrike/falconctl -g --rfm-state
# Expected output: rfm-state=false (sensor is communicating with cloud)

Step 4: Deploy Falcon Sensor - macOS

# Install sensor package
sudo installer -pkg FalconSensorMacOS_7.18.pkg -target /

# Set CID
sudo /Applications/Falcon.app/Contents/Resources/falconctl license <YOUR_CID>

# Grant Full Disk Access and System Extension via MDM profile
# Required for macOS Ventura+ (manual approval or MDM PPPC profile)
# MDM payload: com.crowdstrike.falcon.Agent → SystemExtension + Full Disk Access

# Verify sensor status
sudo /Applications/Falcon.app/Contents/Resources/falconctl stats

Step 5: Configure Prevention Policies

In Falcon Console, navigate to Configuration → Prevention Policies:

Recommended prevention policy settings:

Machine Learning:
  - Cloud ML: Aggressive (extra protection, may increase false positives)
  - Sensor ML: Moderate
  - Adware & PUP: Moderate

Behavioral Protection:
  - On Write: Enabled (detect malware on file creation)
  - On Sensor ML: Enabled
  - Interpreter-Only: Enabled (detect script-based attacks)

Exploit Mitigation:
  - Exploit behavior protection: Enabled
  - Memory scanning: Enabled (detects in-memory attacks)
  - Code injection: Enabled

Ransomware:
  - Ransomware protection: Enabled
  - Shadow copy protection: Enabled
  - MBR protection: Enabled

Create separate policies for:

• Workstations (aggressive settings)
• Servers (moderate settings to avoid false positives on server workloads)
• Critical infrastructure (maximum protection with exception lists)

Step 6: Configure Response Policies

Real-Time Response:
  - Enable RTR for all sensor groups
  - Configure RTR admin vs. RTR responder roles
  - Enable script execution (for IR teams)
  - Enable file extraction (for forensics)

Network Containment:
  - Pre-authorize containment for specific host groups
  - Configure containment exclusions (allow management traffic)

Automated Response:
  - Enable automated remediation for high-confidence detections
  - Configure kill process action for ransomware detections
  - Enable quarantine for malware file detections

Step 7: Validate Deployment

# Windows: Check Falcon sensor status
sc query csagent
# Expected: RUNNING

# Check sensor version
reg query "HKLM\SYSTEM\CrowdStrike\{9b03c1d9-3138-44ed-9fae-d9f4c034b88d}\{16e0423f-7058-48c9-a204-725362b67639}\Default" /v AgentVersion

# Verify cloud connectivity
# In Falcon Console: Host Management → Hosts → search for hostname
# Status should show "Online" with last seen timestamp < 5 minutes

Test detection capability:

# CrowdStrike provides test detection samples
# Download CsTestDetect.exe from Falcon Console → Host setup
# Run on endpoint to generate a test detection
.\CsTestDetect.exe
# Verify detection appears in Falcon Console within 60 seconds

Step 8: SIEM Integration

# Falcon SIEM Connector (Streaming API)
# Configure in Falcon Console: Support → API Clients and Keys

# Create API client with scope: Event Streams → Read
# Use falcon-siem-connector or Falcon Data Replicator (FDR)

# Splunk integration:
# Install CrowdStrike Falcon Event Streams Technical Add-on from Splunkbase
# Configure: Settings → Data inputs → CrowdStrike Falcon Event Streams
# Enter API Client ID and Secret
# Index: crowdstrike_events

# Elastic integration:
# Use Elastic Agent with CrowdStrike module
# Configure: Fleet → Agent policies → Add integration → CrowdStrike

Key Concepts

Term	Definition
Falcon Sensor	Lightweight kernel-mode agent (25-30 MB) that collects endpoint telemetry and enforces prevention policies
CID (Customer ID)	Unique identifier that associates the sensor with your CrowdStrike Falcon tenant
RFM (Reduced Functionality Mode)	State where sensor operates with limited capability due to cloud connectivity loss
Sensor Grouping Tags	Labels applied during installation to auto-assign hosts to groups and policies
RTR (Real-Time Response)	Remote shell capability for incident responders to interact with endpoints through Falcon
IOA (Indicators of Attack)	Behavioral detections based on adversary techniques rather than static signatures

Tools & Systems

• CrowdStrike Falcon Console: Cloud-hosted management platform for all Falcon modules
• Falcon SIEM Connector: Streams detection and audit events to SIEM platforms
• Falcon Data Replicator (FDR): Streams raw endpoint telemetry to S3/cloud storage for hunting
• CrowdStrike Falcon API (OAuth2): RESTful API for automation, integration, and custom workflows
• PSFalcon: PowerShell module for CrowdStrike Falcon API automation

Common Pitfalls

• Missing CID during installation: Sensor installs but never connects to Falcon cloud. Always pass CID during install, not after.
• Proxy not configured: In environments with web proxies, configure proxy during installation: /install /quiet CID=<CID> APP_PROXYNAME=proxy.corp.com APP_PROXYPORT=8080.
• macOS System Extension blocked: macOS requires explicit approval for kernel/system extensions. Use MDM to pre-approve CrowdStrike extensions before deployment.
• Conflicting security products: Running multiple EDR/AV products causes performance issues and false positives. Coordinate exclusions or remove legacy AV before Falcon deployment.
• Sensor version pinning: Falcon auto-updates sensors by default. Pin sensor versions in the console for change-controlled environments before testing new versions.