Complete Guide on API Security for Mobile Apps

Businesses have gone mobile-first, and with good reason—people are spending more time and more money on their phones than ever before. For instance, in 2023, an estimated 66% or 2/3rds of all online orders were made from mobile devices. And in 2024, businesses are expected to spend $402 billion on mobile advertising.

Mobile apps have become the first choice for users for their online activities in banking, e-commerce, media streaming, social media, etc. Increasingly, mobile apps on smartphones ‘talk’ to each other. 

According to a recent study, attacks on APIs have increased by 117% yearly. Even a single user data breach or a few hours of downtime can impact a business to millions of dollars. Businesses can no longer afford to allow the security of their mobile APIs to take a backseat.

Why is securing mobile APIs of critical importance?

We have grown accustomed to personalized and seamless user experiences across multiple apps. APIs power these interactions between mobile apps. 

As mobile apps continue to grow, APIs have become ubiquitous, and their threat landscape has rapidly expanded. 

Here’s why you should consider security for mobile APIs as mission-critical: 

• APIs carry sensitive user information such as login credentials, financial information, personal details, etc. A data breach that compromises personal information can have grave social and economic consequences for thousands of users.
  
• An API can have multiple mobile apps as its endpoints. Attackers who gain access to an unprotected API can disrupt services for a few hours and/or steal confidential user data from multiple apps. Businesses can lose millions of dollars, not to mention the loss of reputation.
  
• A data breach can invite legal action and financial penalties due to non-compliance with data protection regulations such as GDPR, CCPA, HIPAA, etc.

Unsurprisingly, enterprises now consider the need to discover and remediate vulnerabilities in both owned and used mobile APIs as mission-critical.

Expert opinion 

Raghunandan J, Appknox’s Senior Product Manager, believes that:
“API security in mobile apps is essential to ensure reliable user experiences, maintain the integrity of data transactions, and ensure compliance with industry regulations.

Appknox supports developers by providing thorough security evaluations and continuous monitoring, helping them secure their APIs against evolving threats.”

So, what is API security for mobile apps?

API security for mobile apps refers to the processes and tools used to protect the integrity of both owned and used mobile APIs and safeguard against attacks that seek to exploit sensitive data and/or disrupt services.

Security teams now focus exclusively on mobile app API testing and increasingly rely on application security testing software (mostly the SAST tools) to test and secure mobile APIs. 

However, when it comes to their effectiveness in testing the security of mobile app APIs, app security testing software has limitations that make them less than ideal choices as mobile app API testing tools.

• API security for mobile apps refers to the processes and tools used to protect the integrity of both owned and used mobile APIs and safeguard against attacks that seek to exploit sensitive data and/or disrupt services.
• Security teams now focus exclusively on mobile app API testing and increasingly rely on application security testing software (mostly the SAST tools) to test and secure mobile APIs. 
• However, when it comes to their effectiveness in testing the security of mobile app APIs, app security testing software has limitations that make them less than ideal choices as mobile app API testing tools.

The question that then confronts enterprises is, how do we test the security of mobile app APIs? The answer lies in automated application security testing. 

Why should you automate mobile app API security testing?

Mobile app APIs are growing exponentially and becoming more sophisticated by the minute. 

Besides, manually testing a considerable volume of mobile APIs can be tedious and time-consuming, not to mention a huge drain on the security testing team’s bandwidth. When it takes time to discover and resolve security vulnerabilities, security testing can hold up the production/release cycle.

In addition, the limitations of manual testing, such as incomplete coverage of APIs in security tests, leave the door open for attackers to exploit API security vulnerabilities. These issues pose a severe challenge to remediating the security posture of mobile app APIs. 

Automating API security testing frees up critical resources and ensures a more robust security posture for your mobile APIs. 

In particular, automated dynamic application security testing, or DAST, offers a practical approach to mobile app API testing as

• A DAST tool tests your mobile applications in run-time, stimulates clicks on every app component on every screen, and triggers calls to all the APIs used by the mobile app. This creates a directory of all API calls made by the app.
• Automated DAST ensures comprehensive security testing coverage and that no API is overlooked. That way, all potential security vulnerabilities are detected and fixed to minimize threat exposure.
• A DAST tool automatically replicates real-life interactions on your app on a wide range of real devices. This overcomes the limitations of emulator-based testing, efficiently identifies potential security vulnerabilities, and delivers accurate test results.
• A DAST tool lets you schedule automated security scans for multiple mobile applications simultaneously, allowing you to perform security tests swiftly and without manual intervention. This accelerates app development and facilitates faster releases.
• A DAST tool performs deep vulnerability scanning to identify security vulnerabilities in your mobile app APIs accurately. The detailed insights from the vulnerability scanning report can help you proactively mitigate security risks.

Watch an on-demand webinar to learn more about API security testing.

A three-step API security framework for your organization

Adopting an API security framework that everyone in the organization can align on helps contain security threats arising from the increased usage of APIs.

An API security framework outlines simple yet critical protocols related to using APIs. Let’s look at a three-step API security framework you can implement in your organization.

Step 1: Continuous API discovery and specification creation

Continuous API discovery is essential to building and maintaining an up-to-date inventory of APIs in use in your organization. Lack of visibility into what APIs and how many are in use across your organization presents one of the biggest challenges to API security. 

As APIs undergo changes and updates and new versions are released, updating API specifications must be maintained so everyone understands what the API does. 

In short, API discovery and specification are necessary for a comprehensive security assessment of all APIs in use at your organization.

Step 2: Continuous API specification analysis and inspection

The next step entails conducting the right type of security testing: 

• Verifying if the updated API has the right data encryption, 
• Relying on proper authentication and authorization policy, 
• Determining which data sources are being accessed, etc.

Such security testing helps prevent data breaches. 

This is where API security automation tools truly shine, as they can quickly and dynamically find potential vulnerabilities within the API’s authentication and encryption layers.

Step 3: API policy enablement and enforcement

The final step of the API security framework is policy creation and enforcement. This requires answering two questions: 

1. Who should be able to use the API? (ensures fair usage of the API)
2. What level of sensitivity, regulatory oversight, and/or privacy concerns does the API have? (enforce the right level of access control)

Using policies to manage aspects of an API, such as authentication, authorization, encryption, and API availability, helps secure your mobile app, user data, and APIs, ensuring they function and perform as expected.

Although API policy enforcement was traditionally done at the network gateway layer, cloud and mobile architectures have forced developers to provide security aspects through SDKs and the dashboards of cloud service platform providers.

How to choose the right API security automation tool?

Choosing the right API security automation tool is key to ensuring a robust security posture for your organization.

Consider the following factors when evaluating an API security automation tool for your business:

Accuracy

Your security automation tool should 

1. Ensure complete test coverage of all APIs used in your mobile application and
2. Detect and report all possible vulnerabilities accurately. 

If the results of each API security test show many false positives, your engineering/ DevOps teams will need to filter the results to identify the actual security vulnerabilities manually.

Coverage

The threat landscape for mobile APIs is constantly evolving. You need an API security automation tool that provides comprehensive security coverage against various known threats. 

The tool should ensure preparedness against emerging threats by integrating with threat intelligence databases and receiving real-time updates.

Scalability

When choosing an API security automation tool, account for the possibility that your product offerings will continue to grow. Your security testing efforts will need to scale to secure a growing number of mobile apps, APIs, endpoints, calls, and parameters.

Cost

Your engineering and DevOps teams might have built your security testing tech stack by combining numerous point-solution tools. However, the license costs for multiple tools make security testing expensive. 

A good security testing automation platform consolidates your testing tech stack, replaces multiple disparate tools, and drastically reduces expenses on license fees.

Speed

When mobile API security testing proceeds slowly, discovering and resolving security threats takes a long time. This delays development cycles and time to market and affects the business’s bottom line. 

The right API security automation tool reduces the time to complete security tests by

• Automating security scans, 
• Running tests on multiple mobile apps simultaneously and 
• Performing comprehensive tests in one go.

Automation

Engineering and DevOps resource bandwidth takes a lot of work to come by. 

Manually testing every permutation and combination of API calls, endpoints, and parameters can become a herculean task, and teams simply cannot allocate the time and resources required. 

Automated API security testing is more accurate, helps you cover a larger attack surface in less time, and can ensure a robust security posture against emerging threats through frequent security scans.

Why we built API security testing at the core of Appknox’s vulnerability assessment

Mobile app APIs are fast becoming the vector of choice for attackers. Enterprises must identify and resolve security vulnerabilities across their API inventory to safeguard against data breaches and/or service disruptions. 

Here’s why developers and security researchers looking to build safe and secure mobile ecosystems rely on Appknox as their trusted API security testing partner (and why you should, too):

• Appknox combines mobile-first vulnerability assessment, automated DAST, and penetration-testing-as-a-service into one cost-effective, enterprise-grade solution that can form the backbone of your mobile API security testing tech stack.
• Automate testing of mobile app vulnerabilities during runtime on real devices,
• Low levels of false positives (<1%) ensure a highly efficient API security testing process,
• Comprehensive security scan reports that detail the detected issues’ business impact, ways to remediate vulnerabilities and compliance issues,
• Adhere to OWASP best practices for application security testing and
• Comply with data protection regulations such as HIPAA, PCI-DSS, and GDPR.

Appknox’s unique hybrid approach of ‘system plus human’ provides a holistic approach to maintaining a robust security posture. Integrating Appknox with threat intelligence databases ensures that your mobile app APIs are safeguarded against known and evolving security threats.

In conclusion, if you are an enterprise looking to take control of your mobile app security, you need not look any further.