Introduction to OWASP Top 10 API Security Risks - 2019 and F5 Distributed Cloud WAAP

Introduction to API:

An application programming interface (API) is a combination of protocols, functions, etc. which we can utilize to get details about resources, services and features. APIs are fast, lightweight and reliable but they expose sensitive data and so they have become the targets of hackers.


Overview of OWASP API Security:

The simplicity of APIs has given hackers a chance to infiltrate them in plethora of ways to steal personal and sensitive details. Increase in demand of API security caused a need for a project to keep track of latest API vulnerabilities and security procedures called OWASP API Security Top 10.

As per the above project below are the top ten issues and their overview in API security as of 2019.

  1. API1:2019 Broken Object Level Authorization
    APIs expose endpoints that manage objects using unique identifiers, providing hackers a chance to bypass access controls. To prevent this attacks authorized checks like credentials and API token should always be kept in place in the code if there is a request using a user input.
  2. API2:2019 Broken User Authentication
    Authentication mechanisms are sometimes implemented with less security, allowing attackers to compromise authentication tokens to take over other user's identities.
  3. API3:2019 Excessive Data Exposure
    In most of the recent attacks it was observed developers are exposing unnecessary and sensitive object properties providing illegal users a way to exploit them. For more information about this vulnerability, demonstration scenario and prevention steps using F5 XC refer to the article.
  4. API4:2019 Lack of Resources & Rate Limiting
    APIs do not have any restrictions on the size or number of resources that can be requested by the end user. Above mentioned scenarios sometimes lead to poor API server performance, Denial of Service (DoS) and brute force attacks. For more information about this vulnerability, demonstration scenario and prevention steps using F5 XC refer to the article.
  5. API5:2019 Broken Function Level Authorization
    Most applications are composed of different groups, users and roles. If configurations like access control are not applied, it will lead to authorization flaws allowing one user to access the resources of other users.
  6. API6:2019 Mass Assignment
    Code sanity should always be performed in response data, binding client data into code variables without filtering gives hackers a chance to guess object's properties by exploring the API endpoints, documentations, etc.
  7. API7:2019 Security Misconfiguration
    This attack is mostly caused because of misconfigured HTTP headers, unnecessary HTTP methods, permissive Cross-Origin resource sharing (CORS), and verbose error messages in logs containing sensitive information like usernames, PIN, IP addresses, etc. For more information about this vulnerability, demonstration scenario and prevention steps using F5 XC refer to the article.
  8. API8:2019 Injection
    OS commands, SQL, Command Injection, etc., occur if there are no restrictions on user requested schema as part of filter query. The malicious request can sometimes bypass these validations to execute unintended commands providing attackers access to sensitive information. For more information about this vulnerability, demonstration scenario and prevention steps using F5 XC refer to the article.
  9. API9:2019 Improper Assets Management
    A modern web application typically hosts thousands of requests. It is critical to update the  documentation/swagger as per the latest changes and include information about newly implemented APIs. If they are not regularly updated hackers can explore and find any deprecated API which may sometimes expose debug endpoints. For more information about this vulnerability, demonstration scenario and prevention steps using F5 XC refer to the article.
  10. API10:2019 Insufficient Logging & Monitoring
    Any issues in logging and monitoring services will give attackers more ways to attack systems without being recognized. It’s always advised to configure the best monitoring solutions to keep track of all logs and to configure email alerts. Sometimes it’s the best practice to keep logging details in a different location to avoid malicious user activity erasing their log trails. For more information refer to the article.


Overview of F5 Distributed Cloud WAAP:

Web Application and API protection (WAAP) is a SAAS offering provided by F5 Distributed Cloud Services to protect applications and published APIs using Web Application Firewall (WAF), bot protection, API security, and DDoS mitigation. Once WAAP policy is applied on the load balancer, these service engines protect web applications and API endpoints with the latest automatic detection of WAF, Bot and DOS attack signatures.

One of the key sections of Distributed Cloud WAAP is API security which focuses primarily on securing the API’s using different configurations like OpenAPI ingestion, automatic API discovery, service policies, rate limiting, Allow/Denied URLs, etc.

Below diagram shows how Distributed Cloud WAAP protects APIs:

  1. Whenever there is a request originating from end users Distributed Cloud WAAP analyses the request metadata details like URL, filter parameters, Headers, etc. to find whether it’s a legitimate request.
  2. Once the request is screened, validated and approved then only the request is forwarded to the back-end servers. Back-end servers then return the requested details to the end user.
  3. If for any reason Distributed Cloud WAAP finds the request has discrepancies or is not valid the request will be blocked, and a security event will be generated in dashboard.
  4. Users or administrators can analyze the captured request details and can modify the existing Distributed Cloud WAAP configurations if needed to reach the business goals.

Articles on OWASP API Security:


  • Articles on remaining OWASP API Security Top 10 2019 vulnerabilities are in pipeline and will get published shortly, stay tuned for the update
  • New edition of OWASP API Security Top 10 risks - 2023 is released and you can check this link for more details

Related Links:

Updated Jul 24, 2023
Version 11.0

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