API Security by the Numbers
APIs face increasing security threats. Here are critical statistics that highlight the importance of API security testing.
Report at least three API-related data breaches in the last two years
Reported a data breach in the last two years
Consider API Sprawl as their top challenge
Believe APIs increase the attack surface
What is API Pentesting?
API Penetration Testing is a sort of security testing that is done on APIs in order to evaluate the robustness of their security protections. It seeks to detect security flaws that attackers may use to gain access to sensitive data or carry out other destructive acts.
This entails attempting to attack the API in the same way that an attacker would discover any vulnerabilities to exploit. This covers testing for SQL injection, cross-site scripting (XSS), and other API-level flaws.
Types of API Pentesting Services
There are mainly 3 types of APIs that we test, each with unique security challenges.
REST API
A REST API is a type of application programming interface that adheres to the REST architectural style and allows interaction with RESTful web services.
SOAP API
SOAP is a secure API development protocol that operates by encoding data in the XML format, providing robust security features.
GraphQL API
GraphQL is a query language for API and server-side runtime for query execution utilizing a type system you specify for your data.
Common API Vulnerabilities
Here are some of the most common vulnerabilities that attackers exploit in APIs.
Broken Authentication
Individuals who should not have access to particular things are able to access them due to broken or weak authentication mechanisms.
Injection Attacks
This is produced by injecting malicious code into the API, usually in the form of SQL or XSS, allowing data theft or system compromise.
Exposed Data
Inadequate end-to-end data encryption can disclose sensitive information to the public, creating serious security risks.
Misconfigurations
When security setups are left to default or incomplete, they create points of failure that attackers can exploit.
Benefits of API Pentesting
API pen testing is beneficial to businesses in many ways. Here are some of the major advantages.
Maintaining Compliance
Ensure adherence to standards like HIPAA, GDPR, and PCI-DSS to avoid regulatory penalties.
Defending Against Cyberattacks
Detect and fix vulnerabilities before hackers exploit them, preventing financial and reputational damage.
Cost-Effective
Quick remediation of vulnerabilities is more cost-effective than dealing with breach consequences.
Increases Trust
Build client trust and dependability on your organization's services and security procedures.
Our Testing Methodology
Our systematic API penetration testing workflow ensures comprehensive security assessment.
1. Information Gathering
Obtain comprehensive information including architecture schematics, network topologies, user roles, and data flows.
2. Planning
Define objectives, create comprehensive testing methodology, and prepare necessary tools and environments.
3. Auto Tool Scan
Utilize specialized tools to scan for surface-level vulnerabilities and security gaps in the staging environment.
4. Manual Testing
Conduct thorough analysis of APIs in pre and post-authentication phases to identify complex vulnerabilities.
5. Reporting
Provide comprehensive reports with detailed findings, risk assessments, and remediation recommendations.
6. Remediation Testing
Verify that identified vulnerabilities have been properly remediated and security improvements are effective.
Frequently Asked Questions
Everything you need to know about API penetration testing.
The OWASP API Security Top 10 is the global standard list of the most critical API vulnerabilities. The 2023 edition covers: API1 Broken Object Level Authorization (BOLA/IDOR), API2 Broken Authentication, API3 Broken Object Property Level Authorization, API4 Unrestricted Resource Consumption, API5 Broken Function Level Authorization, API6 Unrestricted Access to Sensitive Business Flows, API7 Server Side Request Forgery (SSRF), API8 Security Misconfiguration, API9 Improper Inventory Management (shadow APIs), and API10 Unsafe Consumption of APIs. iSecNet tests every single one of these categories on every engagement, and our report maps each finding directly to its OWASP API reference — making it easy for your developers to understand severity and for your compliance team to demonstrate coverage.
API Security Misconfiguration (OWASP API8) covers deployment and configuration mistakes that expose APIs unnecessarily. iSecNet checks for: CORS misconfiguration allowing any origin to call your API with credentials, HTTP methods enabled that should be disabled (PUT, DELETE on read-only endpoints), verbose error messages exposing stack traces or database schema details, missing security headers (CSP, X-Frame-Options, HSTS), unauthenticated access to API documentation (Swagger UI, Redoc) in production, and disabled TLS or outdated cipher suites. These are low-effort to find but often high-impact because they expose your entire API architecture to reconnaissance.
JWT and OAuth 2.0 are widely used but frequently misimplemented. For JWT, iSecNet tests: algorithm confusion attacks (changing alg:RS256 to alg:none to bypass signature verification), weak secret keys that can be brute-forced, missing expiry validation, sensitive data in the payload, and JWT revocation failures. For OAuth 2.0, we test: redirect URI manipulation, authorization code interception, state parameter CSRF, implicit flow token leakage, and overly broad scope grants. These are logic-level flaws that automated scanners routinely miss and that can give attackers full account takeover without knowing any user's password.
Shadow APIs are endpoints that exist in production but are not officially documented, monitored, or maintained — including old API versions never decommissioned, internal admin endpoints accidentally exposed, debug endpoints left from development, and third-party integration APIs on your domain. They matter because they receive no security updates, have no monitoring, and are invisible to most security tools. OWASP API9 (Improper Inventory Management) is dedicated to this category. iSecNet performs systematic shadow API discovery on every engagement using DNS enumeration, JavaScript analysis, mobile app traffic interception, and path fuzzing.
Yes, and for APIs with real user data, staging testing is strongly preferred. However, staging environments often have subtle differences from production: different authentication configurations, seed data that doesn't represent production volumes, disabled rate limiting, and different infrastructure security groups. iSecNet will review your staging setup during scoping and advise on what needs to match production for accurate results. For production-only testing, we conduct testing in a controlled read-heavy manner during off-peak hours and agree a rollback plan. All production testing is covered by a formal Rules of Engagement document.
Multi-tenant SaaS APIs have a unique critical attack surface: tenant isolation. The worst case is Tenant A accessing, modifying, or deleting Tenant B's data — a catastrophic breach exposing every customer simultaneously. iSecNet specifically tests: horizontal privilege escalation (can user from Tenant A access Tenant B's resources by changing an ID?), tenant ID enumeration, admin API endpoints accessible to non-admin tenant users, shared resource contamination (cached data bleeding between tenants), and API key scope — can a Tenant A API key call Tenant B endpoints? Multi-tenant isolation failures are among the most severe and common vulnerabilities in Indian B2B SaaS platforms and are invisible to automated scanners.
Secure Your APIs Today
APIs allow organizations to increase productivity by linking different programs, but growing usage means more attack opportunities. Let iSecNet ensure your API security.