Prowler
The canonical open-source multi-cloud CSPM: provider-agnostic check engine, attack-path correlation, three-tier layering, GitHub Action integration.
Prowler's provider-agnostic core plus per-cloud adapters is why it covers seven surfaces. Adding a cloud is 'write an adapter,' not 'rewrite the engine.' This extensibility seam is the architectural decision behind Prowler's breadth.
Read-only by default is the primary safety property. A compromised or misconfigured Prowler cannot destroy cloud resources — the worst case is a noisy report. This is what makes Prowler safe to run continuously in production.
OCSF normalization is the portability decision. Findings in a standard schema flow into any downstream tool (SIEM, ticketing, Security Hub). This is what makes Prowler the CSPM standard, not just a scanner.
Prowler is not an agent loop. It detects and reports; it does not remediate, diff, or reason over graphs. Scoring it on the agent rubric forces you to see the boundary — and the opportunity: wrapping Prowler in an agent loop turns it from a detector into a defensive harness.