Docker Security Scanning: A Complete Guide to Container Security
Docker

Docker Security Scanning: A Complete Guide to Container Security

Master Docker security scanning with this comprehensive guide covering vulnerability scanning, compliance checks, and best practices for securing containerized applications

March 15, 2024
DevHub Team
5 min read

Docker Security Scanning: A Complete Guide to Container Security

Container security scanning is crucial for identifying vulnerabilities and ensuring compliance in containerized applications. This guide explores tools and best practices for implementing comprehensive security scanning in your Docker environment.

Security Scanning Overview

graph TB subgraph "Scanning Layers" A["Base Image"] B["Dependencies"] C["Application Code"] D["Configuration"] end subgraph "Security Tools" E["Trivy"] F["Snyk"] G["Clair"] H["Docker Scout"] end subgraph "Integration" I["CI/CD Pipeline"] J["Registry Scanning"] K["Runtime Scanning"] end A --> E B --> F C --> G D --> H E --> I F --> J G --> K H --> I classDef security fill:#1a73e8,stroke:#fff,color:#fff class A,B,C,D,E,F,G,H,I,J,K security

Scanning Tools Comparison

ToolFeaturesBest For
TrivyComprehensive scanningGeneral use
SnykDeep dependency analysisApplication security
ClairContainer scanningEnterprise

Implementation Guide

Trivy Integration

# .github/workflows/security-scan.yml name: Security Scan on: push: branches: [ main ] pull_request: branches: [ main ] jobs: scan: runs-on: ubuntu-latest steps: - uses: actions/checkout@v2 - name: Run Trivy vulnerability scanner uses: aquasecurity/trivy-action@master with: image-ref: 'docker.io/my-organization/my-app:${{ github.sha }}' format: 'table' exit-code: '1' ignore-unfixed: true vuln-type: 'os,library' severity: 'CRITICAL,HIGH'

Snyk Container Scanning

// snyk.config.js module.exports = { docker: { baseImage: 'node:16-alpine', dockerfilePath: './Dockerfile', excludeBaseImageVulns: false, severityThreshold: 'high', ignorePatterns: [ 'SNYK-DEBIAN-OPENSSL-*', 'SNYK-ALPINE-OPENSSL-*' ] }, failOnIssues: true, org: 'my-org-name' };

Vulnerability Management

Scanning Configuration

# trivy.yaml scan: # Vulnerability scanning vulnerability: type: - os - library ignore-unfixed: true severity: - CRITICAL - HIGH # Misconfiguration scanning config: include: - kubernetes - dockerfile severity: - CRITICAL - HIGH - MEDIUM # Secret scanning secret: enable: true

Security Policies

PolicyDescriptionAction
Critical CVEsBlock critical vulnerabilitiesFail build
Base ImagesUse approved base imagesWarn
SecretsDetect hardcoded secretsFail build

CI/CD Integration

GitHub Actions Integration

# .github/workflows/container-security.yml name: Container Security on: push: branches: [ main ] pull_request: branches: [ main ] jobs: security: runs-on: ubuntu-latest steps: - uses: actions/checkout@v2 - name: Build image run: docker build -t myapp:${{ github.sha }} . - name: Scan with Trivy uses: aquasecurity/trivy-action@master with: image-ref: myapp:${{ github.sha }} format: 'sarif' output: 'trivy-results.sarif' - name: Upload scan results uses: github/codeql-action/upload-sarif@v1 with: sarif_file: 'trivy-results.sarif' - name: Scan with Snyk uses: snyk/actions/docker@master env: SNYK_TOKEN: ${{ secrets.SNYK_TOKEN }} with: image: myapp:${{ github.sha }} args: --severity-threshold=high

Jenkins Pipeline

// Jenkinsfile pipeline { agent any environment { DOCKER_IMAGE = 'myapp:${BUILD_NUMBER}' } stages { stage('Build') { steps { sh 'docker build -t ${DOCKER_IMAGE} .' } } stage('Security Scan') { parallel { stage('Trivy') { steps { sh ''' trivy image \ --exit-code 1 \ --severity HIGH,CRITICAL \ --no-progress \ ${DOCKER_IMAGE} ''' } } stage('Snyk') { steps { snykSecurity( snykInstallation: 'snyk', snykTokenId: 'snyk-api-token', targetFile: 'Dockerfile', dockerImage: "${DOCKER_IMAGE}", severity: 'high', failOnIssues: true ) } } } } } }

Runtime Security

Container Runtime Scanning

# falco-rules.yaml - rule: Detect Shell in Container desc: Alert on shell execution in container condition: > container.id != host and proc.name = bash output: Shell executed in container (user=%user.name container=%container.name) priority: WARNING - rule: Package Management Execution desc: Package management execution in container condition: > container.id != host and (proc.name = apt or proc.name = apk or proc.name = yum) output: Package management command executed in container (user=%user.name command=%proc.cmdline) priority: WARNING

Runtime Monitoring

MetricDescriptionAlert Threshold
File ChangesUnexpected modificationsAny change
Network ActivityUnusual connections> 100/min
Process ExecutionNew processesAny shell

Compliance and Auditing

CIS Docker Benchmark

#!/bin/bash # Run Docker Bench Security docker run --rm -v /var:/var \ -v /usr/bin/docker:/usr/bin/docker \ -v /var/run/docker.sock:/var/run/docker.sock \ -v /etc:/etc --label docker_bench_security \ docker/docker-bench-security # Parse results docker run --rm \ -v $(pwd)/results:/results \ docker/docker-bench-security -l /results/bench.log

Compliance Checks

CheckRequirementValidation
Root AccessNo root containersUser directive
Image SigningSigned images onlyDCT verification
Network AccessRestricted portsPort mapping

Best Practices

Security Guidelines

  1. Base Image Selection

    # Use specific version tags FROM alpine:3.17.0 # Add security packages RUN apk add --no-cache \ ca-certificates \ tzdata \ && update-ca-certificates # Create non-root user RUN addgroup -S appgroup && adduser -S appuser -G appgroup USER appuser
  2. Dependency Management

    { "name": "secure-app", "version": "1.0.0", "dependencies": { "express": "4.18.2" }, "scripts": { "security-audit": "npm audit", "update-deps": "npm update" } }

Troubleshooting Guide

Common Issues

IssueCauseSolution
False PositivesOutdated DBUpdate scanner
Scan FailuresResource limitsIncrease memory
Missing ResultsConfigurationCheck settings

References

  1. Docker Security Documentation
  2. Trivy Documentation
  3. Snyk Container Security
  4. CIS Docker Benchmark
  5. Container Security Best Practices
  6. NIST Container Security Guide

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