Scanning IaC and Images with Trivy

Overview

Trivy (by Aqua Security) is a comprehensive, open-source security scanner that finds vulnerabilities (CVEs), misconfigurations (IaC), secrets, software licenses, and software supply-chain weaknesses across a wide range of targets: container images, filesystems, Git repositories, virtual machine images, Kubernetes clusters, and SBOM documents. It is widely adopted as a "shift-left" gate in CI/CD pipelines because it is fast, runs as a single static binary, requires no agent, and supports machine-readable output formats (JSON, SARIF, CycloneDX, SPDX) for integration with code-scanning dashboards.

Trivy bundles four primary scanners that can be toggled with --scanners:

• vuln — OS package and language-dependency vulnerability detection (CVE matching against the Trivy vulnerability DB).
• misconfig — Infrastructure-as-Code and configuration misconfiguration detection (Terraform, CloudFormation, Kubernetes manifests, Dockerfile, Helm) using built-in and custom Rego policies.
• secret — Hard-coded secret/credential detection (API keys, tokens, private keys).
• license — Software license identification and policy enforcement.

This skill covers building a Trivy-based scanning workflow that gates a CI/CD pipeline: scanning images before push, scanning IaC before apply, generating and re-scanning SBOMs, and failing builds on policy violations. Detecting these weaknesses defends against the MITRE ATT&CK technique T1525 (Implant Internal Image), where adversaries plant malicious or vulnerable images in a registry to be deployed across the environment.

When to Use

• When integrating vulnerability and misconfiguration scanning into a CI/CD pipeline as a quality/security gate before images are pushed or infrastructure is applied.
• When auditing container images in a registry for known CVEs prior to deployment.
• When validating Terraform, CloudFormation, Kubernetes, Dockerfile, or Helm IaC for security misconfigurations.
• When generating an SBOM (CycloneDX/SPDX) for supply-chain transparency and later re-scanning that SBOM for newly disclosed CVEs.
• When scanning a running Kubernetes cluster for vulnerable workloads and misconfigured RBAC/resources.
• When enforcing license compliance policy on dependencies.

Prerequisites

• A Linux/macOS/Windows host or CI runner with network access to download the Trivy vulnerability database.
• Docker (optional) if scanning local images by name or using the containerized Trivy.
• Install Trivy (Aqua Security official methods):

# Debian/Ubuntu (APT repository)
sudo apt-get install -y wget gnupg
wget -qO - https://aquasecurity.github.io/trivy-repo/deb/public.key | gpg --dearmor | sudo tee /usr/share/keyrings/trivy.gpg > /dev/null
echo "deb [signed-by=/usr/share/keyrings/trivy.gpg] https://aquasecurity.github.io/trivy-repo/deb generic main" | sudo tee /etc/apt/sources.list.d/trivy.list
sudo apt-get update
sudo apt-get install -y trivy

# RHEL/CentOS (YUM repository), macOS (Homebrew), and install script
brew install trivy
curl -sfL https://raw.githubusercontent.com/aquasecurity/trivy/main/contrib/install.sh | sudo sh -s -- -b /usr/local/bin

# Containerized usage (no install)
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock aquasec/trivy:latest image python:3.10-alpine

# Verify
trivy --version

• For air-gapped or rate-limited environments, pre-download the DB with trivy image --download-db-only and the Java/policy bundles as needed.

Objectives

• Scan a container image for OS and language vulnerabilities and fail the build above a severity threshold.
• Scan IaC (Terraform/Kubernetes/Dockerfile) for misconfigurations.
• Detect hard-coded secrets in a repository or filesystem.
• Generate a CycloneDX or SPDX SBOM and re-scan it for vulnerabilities.
• Emit SARIF for GitHub code scanning and JSON for programmatic gating.
• Wire Trivy into a CI/CD pipeline with --exit-code to enforce policy.

MITRE ATT&CK Mapping

Workflow

1. Scan a container image for vulnerabilities

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