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Understanding Your API Attack Surface: How To Get Started

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API Attack Surface

Mo Amao

Microservices, mobile devices, and cloud computing are all part of our daily lives. We use Application Programming Interfaces (APIs) to interact with almost every programme. Because of this, APIs play a vital role in an organisation’s attack surface. APIs make it possible for various software programmes to interact and communicate with one another, easing processes and improving the functioning of programmes. However, because of their rising popularity, cybercriminals have found them desirable targets. Understanding your API attack surface is essential to maintain the security and integrity of your apps and data.

Bad actors are tenacious and are continuing to find new and unexpected ways to attack. In the past, organizations believed that proper authentication to interact with an API was enough of a deterrent to send attackers elsewhere. Salt Labs data shows that 78% of attacks come from seemingly legitimate users who have maliciously achieved the proper authentication.

This blog explores the API attack surface and introduces steps to ensure API security.

What is an API Attack Surface?

Hackers may target APIs as a profitable target to break into otherwise protected systems and take advantage of flaws. Due to the automated nature of their users, APIs are more vulnerable to resource consumption and rate-limiting problems than web applications. They frequently suffer from the same vulnerabilities as web applications, such as broken access controls, injections, security misconfigurations, and vulnerabilities inherited from other dependent code libraries. Legacy problems from earlier APIs are frequently carried through due to a lack of market expertise.

The API attack surface is the total number of potential points of entry that attackers may use to breach an API or the system that supports it. Understanding the scope of each API’s attack surface is the first step in developing a solid security plan. Endpoints, parameters, authentication techniques, and data transmission methods are typical elements of an API attack surface.

How to Assess Your API Attack Surface Identify and Document Your APIs

Finding all the APIs your application or system utilises is the first step in determining your API attack surface. Make a thorough list of all these internal and external APIs. The list should contain the API’s name, function, version, and any related documentation or code samples. This material will be an essential resource as you move on with the security assessment. In addition to listing the organisational APIs already in use, it is critical to recognise and comprehend the most typical API security issues. Fortunately, an API Security Top 10 list has been created by the OWASP community, which is always beneficial. This includes broken object and user authentication, data leakage, and no rate limits.

Perform Threat Modelling Exercise

Threat modelling is a proactive method of security that aids in spotting prospective threats and vulnerabilities before attackers can exploit them. Gather your development and security teams for each API to perform a threat modelling exercise. This activity examines the API’s design, implementation, and usage scenarios to identify potential attack vectors. Consider the following crucial factors as you work through the threat modelling process:

  • Check the data flow between the API’s endpoints and the systems it communicates with. Find any data inputs that might be changed to take advantage of vulnerabilities.
  • Consider the authentication and permission procedures used by the API to ensure that access controls are correctly applied and upheld.
  • Ensure all input data is thoroughly verified and cleaned to thwart injection attacks.
  • Check the API’s error handling procedures to see if it exposes sensitive information that an attacker could use against you.
  • Implement strategies to stop API abuse by limiting rate and throttling API calls.

Conduct security audits

After using threat modelling to identify potential threats and vulnerabilities, conduct security audit and testing. There are various methods for security testing, such as:

  • Utilise a knowledgeable group of ethical hackers for penetration testing to replicate actual attacks on your APIs and spot flaws.
  • Fuzz testing: Employ automated techniques to flood the API endpoints with erroneous and random data to find concealed vulnerabilities.
  • Code Review: Carefully examine the API’s source code to find security holes and confirm that best practices are being used.

Implement Security Best Practices

  • Use robust authentication mechanisms such as OAuth, API keys, or JWT tokens to ensure that only authorised users may access the API.
  • HTTPS: Use HTTPS to encrypt data transmission to safeguard sensitive information from interception.
  • Implement strong input validation to prevent injection attacks and to ensure that only legitimate data is processed.
  • Deploy runtime security tooling purpose-built for APIs to enable detection of the “low and slow” attacks common for APIs today.
  • Implement rigorous logging and monitoring to discover and respond to suspicious actions immediately.
  • Patch Management and Regular Updates: Keep all software and libraries used in the API updated with the latest security fixes.


API security is an ongoing activity requiring constant monitoring and timely response to potential threats. By adopting proactive measures, businesses may ensure their APIs are safe and secure for their users and customers. API Scanning makes it simple to improve your API security. Identify and address vulnerabilities such that no potential entry points are left open. Protect your applications with confidence. Understanding your API attack surface is critical for guaranteeing application security and protecting sensitive data. Businesses can decrease the risk of API-related security breaches by detecting potential threats, undertaking security testing, and following best practices. To keep your applications safe, stay watchful, regularly monitor your APIs, and update your security procedures when new threats emerge.

MosopefoluwaMosopefoluwa is a certified Cybersecurity Analyst and Technical writer. She worked as a Security Operations Center (SOC) Analyst, creating relevant cybersecurity content for organizations and spreading security awareness. Volunteering as an Opportunities and Resources Writer with a Nigerian based NGO she curated weekly opportunities for women. She is also a regular writer at Bora.

Her other interests are law, volunteering and women’s rights. In her free time, she enjoys spending time at the beach, watching movies or burying herself in a book.

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