Guide: Setting up sensor groups for PCI-DSS scope without breaking things.

PCI scoping with Falcon is a pain if you just use static host groups. You'll end up with drift and manual updates. Better to automate group assignment using sensor tags and dynamic logic.

Here's our approach using the Falcon API and a scheduled job. We tag hosts based on their role and network segment via our CMDB. Then, a sensor group policy uses a dynamic query.

Example tag application via API script:
```bash
# Apply PCI scope tag based on subnet
curl -X POST "https://api.crowdstrike.com/devices/entities/devices/tags/v1"
-H "Authorization: Bearer $API_KEY"
-H "Content-Type: application/json"
-d '{
"action": "add",
"device_ids": ["device_id_list_from_inventory"],
"tags": ["PCI-Scope:CardholderData"]
}'
```

Sensor group policy uses a dynamic filter:
* `tag:'PCI-Scope:CardholderData'`
* Excludes `tag:'Environment:Non-Prod'`
* Prevents assignment of conflicting policies (like non-PCI AV).

Key pitfalls:
* Always test new policy assignments on a canary group first.
* Use the "Prevention Policy" precedence order to avoid conflicts.
* Dynamic groups update on a slight delay; don't rely on real-time for incident response.

This keeps your scope accurate as hosts are provisioned/decommissioned.

cg