undermybelt Implementing API Security Testing with 42Crunch
Overview
42Crunch is an API security platform that combines Shift-Left security testing with Shield-Right runtime protection. It provides API Audit for static security analysis of OpenAPI definitions, API Conformance Scan for dynamic vulnerability detection, and API Protect for real-time threat prevention. The platform integrates into CI/CD pipelines and IDEs to identify OWASP API Security Top 10 vulnerabilities before and after deployment.
When to Use
- When deploying or configuring implementing api security testing with 42crunch capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Prerequisites
- 42Crunch platform account (free tier available for evaluation)
- OpenAPI Specification (OAS) v2.0, v3.0, or v3.1 definitions for target APIs
- IDE with 42Crunch extension (VS Code, IntelliJ, or Eclipse)
- CI/CD pipeline (Jenkins, GitHub Actions, Azure DevOps, or GitLab CI)
- Running API instance for dynamic scanning (conformance scan)
- Node.js or Python environment for CLI tooling
Core Concepts
API Audit (Static Analysis)
API Audit performs static security analysis of OpenAPI definitions without requiring a running API. It evaluates the specification against 300+ security checks organized into categories:
Security Score Categories:
- Data Validation: Schema definitions, parameter constraints, response validation
- Authentication: Security scheme definitions, scope requirements
- Transport Security: Server URL schemes, TLS requirements
- Error Handling: Error response definitions, information leakage prevention
Running API Audit via VS Code Extension:
- Install the 42Crunch extension from the VS Code marketplace
- Open an OpenAPI specification file (YAML or JSON)
- Click the security audit icon in the editor toolbar
- Review the security score (0-100) and individual findings
- Address issues using the inline remediation guidance
Example OpenAPI Definition with Security Controls:
openapi: 3.0.3
info:
title: Secure User API
version: 1.0.0
servers:
- url: https://api.example.com/v1
description: Production server (HTTPS only)
security:
- BearerAuth: []
paths:
/users/{userId}:
get:
operationId: getUserById
summary: Retrieve user by ID
parameters:
- name: userId
in: path
required: true
schema:
type: string
format: uuid
pattern: '^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$'
maxLength: 36
responses:
'200':
description: User details
content:
application/json:
schema:
$ref: '#/components/schemas/User'
'400':
description: Invalid request
content:
application/json:
schema:
$ref: '#/components/schemas/Error'
'401':
description: Unauthorized
'404':
description: User not found
components:
securitySchemes:
BearerAuth:
type: http
scheme: bearer
bearerFormat: JWT
schemas:
User:
type: object
required:
- id
- email
properties:
id:
type: string
format: uuid
readOnly: true
email:
type: string
format: email
maxLength: 254
name:
type: string
maxLength: 100
pattern: '^[a-zA-Z\s\-]+$'
additionalProperties: false
Error:
type: object
required:
- code
- message
properties:
code:
type: integer
format: int32
message:
type: string
maxLength: 256
additionalProperties: false
API Conformance Scan (Dynamic Testing)
The conformance scan dynamically tests a running API against its OpenAPI contract to detect runtime vulnerabilities including OWASP API Security Top 10 issues:
Scan v2 Configuration:
# 42c-conf.yaml
version: "2.0"
scan:
target:
url: https://api.example.com/v1
authentication:
- type: bearer
token: "${API_TOKEN}"
in: header
name: Authorization
settings:
maxScanTime: 3600
requestsPerSecond: 10
followRedirects: false
tests:
owasp:
- bola
- bfla
- injection
- ssrf
- massAssignment
- excessiveDataExposure
Running Conformance Scan via CLI:
# Install the 42Crunch CLI
npm install -g @42crunch/cicd-cli
# Run conformance scan
42crunch-cli scan \
--api-definition ./openapi.yaml \
--target-url https://api.example.com/v1 \
--token $CRUNCH_TOKEN \
--min-score 70 \
--report-format sarif \
--output scan-report.sarif
CI/CD Pipeline Integration
GitHub Actions Integration:
name: API Security Testing
on:
push:
paths:
- 'api/**'
- 'openapi/**'
jobs:
api-security:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- name: 42Crunch API Audit
uses: 42Crunch/api-security-audit-action@v3
with:
api-token: ${{ secrets.CRUNCH_API_TOKEN }}
collection-name: "my-api-collection"
min-score: 75
upload-to-code-scanning: true
- name: 42Crunch Conformance Scan
if: github.ref == 'refs/heads/main'
uses: 42Crunch/api-conformance-scan@v1
with:
api-token: ${{ secrets.CRUNCH_API_TOKEN }}
target-url: ${{ secrets.STAGING_API_URL }}
scan-config: ./42c-conf.yaml
Jenkins Pipeline Integration:
pipeline {
agent any
stages {
stage('API Security Audit') {
steps {
script {
def auditResult = sh(
script: '''
42crunch-cli audit \
--api-definition openapi.yaml \
--token ${CRUNCH_TOKEN} \
--min-score 75 \
--report-format json \
--output audit-report.json
''',
returnStatus: true
)
if (auditResult != 0) {
error("API Security Audit failed - score below threshold")
}
}
}
}
stage('Conformance Scan') {
when { branch 'main' }
steps {
sh '''
42crunch-cli scan \
--api-definition openapi.yaml \
--target-url ${STAGING_URL} \
--token ${CRUNCH_TOKEN} \
--scan-config 42c-conf.yaml
'''
}
}
}
post {
always {
archiveArtifacts artifacts: '*-report.*'
publishHTML([
reportDir: '.',
reportFiles: 'audit-report.html',
reportName: 'API Security Report'
])
}
}
}
API Protect (Runtime Protection)
API Protect deploys as a micro-gateway in front of API endpoints to enforce the OpenAPI contract at runtime:
# api-protect-config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: api-protect-config
data:
protection-config.json: |
{
"apiDefinition": "/config/openapi.yaml",
"enforcement": {
"validateRequests": true,
"validateResponses": true,
"blockOnFailure": true,
"logLevel": "warn"
},
"rateLimit": {
"enabled": true,
"requestsPerMinute": 100,
"burstSize": 20
},
"allowlist": {
"contentTypes": ["application/json"],
"methods": ["GET", "POST", "PUT", "DELETE"]
}
}
Remediation Workflow
When 42Crunch identifies issues, follow this remediation process:
- Triage: Review findings sorted by severity (Critical, High, Medium, Low)
- Analyze: Understand the specific security control missing from the OpenAPI definition
- Fix: Apply the recommended changes to the specification
- Validate: Re-run audit to confirm the score improvement
- Deploy: Push the updated specification through the CI/CD pipeline
Common Audit Findings and Fixes:
| Finding | Severity | Fix |
|---|---|---|
| No authentication defined | Critical | Add securitySchemes and security requirements |
| Missing input validation | High | Add type, format, pattern, maxLength constraints |
| Server URL uses HTTP | High | Change server URLs to HTTPS |
| No error responses defined | Medium | Add 4xx and 5xx response definitions |
| additionalProperties not restricted | Medium | Set additionalProperties: false on object schemas |
| Missing rate limiting | Medium | Add x-rateLimit extension or use API Protect |
Key Security Checks
42Crunch evaluates APIs against these critical security areas:
- BOLA Prevention: Validates that object-level authorization patterns are defined
- BFLA Prevention: Checks for function-level access control definitions
- Injection Prevention: Ensures input parameters have proper type/format/pattern constraints
- Data Exposure: Verifies response schemas limit returned properties
- Security Misconfiguration: Checks authentication schemes, transport security, CORS settings
- Mass Assignment: Validates that request bodies use explicit property allowlists
References
- 42Crunch API Security Platform: https://42crunch.com/api-security-platform/
- 42Crunch Documentation: https://docs.42crunch.com/
- Microsoft Defender for Cloud 42Crunch Integration: https://learn.microsoft.com/en-us/azure/defender-for-cloud/onboarding-guide-42crunch
- OWASP API Security Top 10 2023: https://owasp.org/API-Security/editions/2023/en/0x00-header/
- Jenkins Plugin for 42Crunch: https://plugins.jenkins.io/42crunch-security-audit/