API Security Review Inspection Checklist [FREE PDF]

APIs are among the most frequently targeted attack surfaces in modern enterprise environments, with OWASP identifying broken authentication, excessive data exposure, and injection flaws as leading API security risks. Regulatory frameworks including PCI DSS v4.0 Requirement 6.2, NIST CSF PR.PT-3, and ISO 27001:2022 Annex A.8.24 require organizations to apply secure coding practices and perform periodic security assessments of all externally and internally exposed APIs. This checklist enables CISO

  • Industry: Software Development
  • Frequency: Quarterly
  • Estimated Time: 50-70 minutes
  • Role: CISO
  • Total Items: 36
  • Compliance: ISO 27001:2022 Annex A.8.24 (Use of Cryptography), NIST CSF PR.PT-3 (Least Functionality), PCI DSS v4.0 Requirement 6.2 (Bespoke and Custom Software Security), GDPR Article 32 (Security of Processing – Pseudonymisation and Encryption), SOC 2 Type II CC6.6 (Logical and Physical Access – External Transmission)

API Inventory & Classification

Verify that all APIs are inventoried, classified by data sensitivity, and documented with ownership.

  • Is a complete inventory of all internal and external APIs maintained and up to date?
  • Are APIs classified based on the sensitivity of data they transmit or expose?
  • Does each API have a designated owner responsible for its security and maintenance?
  • Are deprecated or retired APIs decommissioned and removed from production environments?
  • How many active APIs are currently in scope for this review?

Authentication & Authorization Controls

Assess the strength of API authentication mechanisms and authorization enforcement across all endpoints.

  • Do all APIs enforce strong authentication (e.g., OAuth 2.0, API keys, mutual TLS) on every request?
  • Are API tokens or keys stored securely and never hardcoded in source code or configuration files?
  • Is role-based or attribute-based access control (RBAC/ABAC) enforced at the API endpoint level?
  • Do APIs enforce token expiration and refresh policies to prevent long-lived credential abuse?
  • What authentication mechanism is primarily used for API access?

Data Encryption & Transmission Security

Verify that all API communications are encrypted in transit and that sensitive data is protected at rest.

  • Do all APIs enforce TLS 1.2 or higher for all data transmitted in transit?
  • Are SSL/TLS certificates valid, issued by a trusted CA, and subject to automated renewal monitoring?
  • Do API responses avoid returning sensitive data fields (e.g., passwords, full PAN, SSNs) not required by the consumer?
  • Is HTTP Strict Transport Security (HSTS) enabled on all public-facing API endpoints?
  • Capture a screenshot of the TLS configuration report or certificate status for APIs in scope.

Input Validation & Injection Prevention

Assess controls to validate API inputs and prevent injection attacks including SQLi, command injection, and schema tampering.

  • Are all API input parameters validated against a defined schema before processing?
  • Are parameterized queries or ORM frameworks used consistently to prevent SQL injection via API inputs?
  • Is API schema validation (e.g., OpenAPI / JSON Schema) enforced at the gateway or application layer?
  • Are file upload endpoints restricted by file type, size, and malware scanning?
  • Provide notes on any injection vulnerabilities or schema validation gaps identified.

Rate Limiting & DoS Protection

Evaluate controls to prevent API abuse, brute force, and denial-of-service attacks through rate limiting and throttling.

  • Is rate limiting enforced on all API endpoints to prevent abuse and brute-force attacks?
  • Are rate limit thresholds defined per API consumer (client ID / API key) rather than globally only?
  • Are 429 Too Many Requests responses returned with Retry-After headers when limits are exceeded?
  • Is a Web Application Firewall (WAF) or API gateway configured to block common DDoS patterns?
  • What is the current maximum requests-per-minute limit applied to authenticated API consumers?

API Logging & Security Monitoring

Verify that API activity is logged comprehensively and that anomalous behavior triggers timely security alerts.

  • Are all API requests and responses (excluding sensitive payload data) logged with timestamps, source IP, and response codes?
  • Are API logs forwarded to a centralized SIEM or log management system in real time?
  • Are alerts configured for anomalous API patterns such as excessive errors, unusual geolocations, or unexpected data volumes?
  • Are API logs retained for a minimum of 12 months with at least 3 months of logs readily accessible?
  • Are sensitive data fields (e.g., tokens, passwords, card numbers) masked or excluded from API logs?

Vulnerability Testing & Remediation

Assess the frequency and quality of API-specific security testing and the process for remediating identified vulnerabilities.

  • Is API-specific penetration testing conducted at least annually by a qualified internal or external team?
  • Are automated Dynamic Application Security Testing (DAST) tools integrated into the CI/CD pipeline for API testing?
  • Are OWASP API Security Top 10 risks explicitly addressed in the API security testing scope?
  • Are critical and high-severity API vulnerabilities remediated within a defined SLA (e.g., critical within 30 days)?
  • What is the overall API security risk rating for this review period?
  • Provide a summary of critical findings, open remediation items, and next review date.

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Why Use This API Security Review Inspection Checklist [FREE PDF]?

This api security review inspection checklist [free pdf] helps software development teams maintain compliance and operational excellence. Designed for ciso professionals, this checklist covers 36 critical inspection points across 7 sections. Recommended frequency: quarterly.

Ensures compliance with ISO 27001:2022 Annex A.8.24 (Use of Cryptography), NIST CSF PR.PT-3 (Least Functionality), PCI DSS v4.0 Requirement 6.2 (Bespoke and Custom Software Security), GDPR Article 32 (Security of Processing – Pseudonymisation and Encryption), SOC 2 Type II CC6.6 (Logical and Physical Access – External Transmission). Regulatory-aligned for audit readiness and inspection documentation.

Frequently Asked Questions

What does the API Security Review Inspection Checklist [FREE PDF] cover?

This checklist covers 36 inspection items across 7 sections: API Inventory & Classification, Authentication & Authorization Controls, Data Encryption & Transmission Security, Input Validation & Injection Prevention, Rate Limiting & DoS Protection, API Logging & Security Monitoring, Vulnerability Testing & Remediation. It is designed for software development operations and compliance.

How often should this checklist be completed?

This checklist should be completed quarterly. Each completion takes approximately 50-70 minutes.

Who should use this API Security Review Inspection Checklist [FREE PDF]?

This checklist is designed for CISO professionals in the software development industry. It can be used for self-assessments, team audits, and regulatory compliance documentation.

Can I download this checklist as a PDF?

Yes, this checklist is available as a free PDF download. You can also use it digitally in the POPProbe mobile app for real-time data capture, photo documentation, and automatic reporting.

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