How to Build a Cloud-Agnostic Threat Exposure Management Program Using Open Source Tools

Security teams can build a Continuous Threat Exposure Management (CTEM) pipeline using entirely open-source, self-hosted tools that work across AWS, Azure, GCP, and on-premises environments. The stack covers the full attack chain — from passive OSINT and subdomain discovery to vulnerability assessment, secret scanning, cloud posture auditing, and identity attack path mapping. Tools such as Amass, Nuclei, TruffleHog, ScoutSuite, and BloodHound are designed as short-lived CLI binaries or containers, eliminating standing infrastructure and per-asset subscription costs. However, a March 2026 compromise of the widely used Trivy scanner — where attackers injected malicious code into its GitHub repos and Docker Hub images — highlights that open-source security tools are not inherently trustworthy. Practitioners are advised to verify signatures and build provenance for every tool before allowing it to run against their infrastructure.