hacktricks/network-services-pentesting/pentesting-web/web-api-pentesting.md

# Web API Pentesting

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## API Pentesting Methodology Summary

Pentesting APIs involves a structured approach to uncovering vulnerabilities. This guide encapsulates a comprehensive methodology, emphasizing practical techniques and tools.

### **Understanding API Types**

- **SOAP/XML Web Services**: Utilize the WSDL format for documentation, typically found at `?wsdl` paths. Tools like **SOAPUI** and **WSDLer** (Burp Suite Extension) are instrumental for parsing and generating requests. Example documentation is accessible at [DNE Online](http://www.dneonline.com/calculator.asmx).

- **REST APIs (JSON)**: Documentation often comes in WADL files, yet tools like [Swagger UI](https://swagger.io/tools/swagger-ui/) provide a more user-friendly interface for interaction. **Postman** is a valuable tool for creating and managing example requests.

- **GraphQL**: A query language for APIs offering a complete and understandable description of the data in your API.

### **Practice Labs**

- [**VAmPI**](https://github.com/erev0s/VAmPI): A deliberately vulnerable API for hands-on practice, covering the OWASP top 10 API vulnerabilities.

### **Effective Tricks for API Pentesting**

- **SOAP/XML Vulnerabilities**: Explore XXE vulnerabilities, although DTD declarations are often restricted. CDATA tags may allow payload insertion if the XML remains valid.

- **Privilege Escalation**: Test endpoints with varying privilege levels to identify unauthorized access possibilities.

- **CORS Misconfigurations**: Investigate CORS settings for potential exploitability through CSRF attacks from authenticated sessions.

- **Endpoint Discovery**: Leverage API patterns to discover hidden endpoints. Tools like fuzzers can automate this process.

- **Parameter Tampering**: Experiment with adding or replacing parameters in requests to access unauthorized data or functionalities.

- **HTTP Method Testing**: Vary request methods (GET, POST, PUT, DELETE, PATCH) to uncover unexpected behaviors or information disclosures.

- **Content-Type Manipulation**: Switch between different content types (x-www-form-urlencoded, application/xml, application/json) to test for parsing issues or vulnerabilities.

- **Advanced Parameter Techniques**: Test with unexpected data types in JSON payloads or play with XML data for XXE injections. Also, try parameter pollution and wildcard characters for broader testing.

- **Version Testing**: Older API versions might be more susceptible to attacks. Always check for and test against multiple API versions.

### **Tools and Resources for API Pentesting**

- **kiterunner**: Excellent for discovering API endpoints. Use it to scan and brute force paths and parameters against target APIs.
```bash
kr scan https://domain.com/api/ -w routes-large.kite -x 20
kr scan https://domain.com/api/ -A=apiroutes-220828 -x 20
kr brute https://domain.com/api/ -A=raft-large-words -x 20 -d=0
kr brute https://domain.com/api/ -w /tmp/lang-english.txt -x 20 -d=0
```

- Additional tools like **automatic-api-attack-tool**, **Astra**, and **restler-fuzzer** offer tailored functionalities for API security testing, ranging from attack simulation to fuzzing and vulnerability scanning.

### **Learning and Practice Resources**

- **OWASP API Security Top 10**: Essential reading for understanding common API vulnerabilities ([OWASP Top 10](https://github.com/OWASP/API-Security/blob/master/2019/en/dist/owasp-api-security-top-10.pdf)).

- **API Security Checklist**: A comprehensive checklist for securing APIs ([GitHub link](https://github.com/shieldfy/API-Security-Checklist)).

- **Logger++ Filters**: For hunting API vulnerabilities, Logger++ offers useful filters ([GitHub link](https://github.com/bnematzadeh/LoggerPlusPlus-API-Filters)).

- **API Endpoints List**: A curated list of potential API endpoints for testing purposes ([GitHub gist](https://gist.github.com/yassineaboukir/8e12adefbd505ef704674ad6ad48743d)).


## References
* [https://github.com/Cyber-Guy1/API-SecurityEmpire](https://github.com/Cyber-Guy1/API-SecurityEmpire)


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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
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