Mobile Application Security Testing (MAST) - Challenges & Tools

Mobile application security testing (MAST) should be part of every organization’s mobile application security strategy. It offers a practical way to identify vulnerabilities and mitigate risks before and after a mobile app gets into the hands of users. Here is everything you need to know about the importance of mobile application security testing, including tips for conducting MAST, common challenges, and industry best practices and tools. Snyk's application security solution can help you get started with MAST, with language coverage for Android & iOS development languages. 

What is mobile application security testing? 

Mobile application security testing assesses risks and vulnerabilities that may exist in applications installed on mobile operating systems (e.g., Android, iOS, Windows 10 Mobile). 

The OWASP Mobile Security Testing Guide notes that similar terms such as "mobile app security review" are sometimes used to refer to MAST. Effective vulnerability analysis in MAST involves static analysis, dynamic analysis, and penetration testing. 

Why is testing important for mobile application security? 

2022 saw over a quarter of a trillion (255 billion) mobile app downloads worldwide — that number is expected to increase to nearly 300 billion downloads in 2023. Mobile devices are high-value targets due to the fact that they have access to a variety of data sources (email, social mediam), a variety of extended functions (microphone, camera, geolocation), and are used in authentication processes (2FA, MFA). And due to its openness, Android is especially vulnerable.

Mobile application security has become a core focus of enterprise cybersecurity programs because organizations are constantly releasing new apps and updating existing ones, yielding countless opportunities for threat actors to access large swaths of sensitive information. 

MAST is a tactic that fits into a robust mobile application security strategy, alongside other practices such as designing secure architectures, implementing secure coding practices, and minimizing the storage of sensitive data. 

Concerningly many businesses have significant room for improvement when it comes to their mobile application security. One large-scale survey found that three in four mobile apps contain at least one moderate security vulnerability. 

What methods can be used for mobile application security testing? 

Some of the most popular mobile application security testing methods include: 

• Manual testing: A human tester manually interacts with the application to identify vulnerabilities. Manual app testing is best used to detect higher-level, more abstract application issues, such as design flaws and business logic errors.

• Automated testing: An automated MAST solution is used to scan application code for potential vulnerabilities, allowing development teams to identify security risks as early as possible. Other benefits include speed, accuracy, scalability, and cost-efficiency. 

• Bug bounties: Organizations offer monetary rewards or other incentives to security researchers and ethical hackers who identify and disclose vulnerabilities within an organization’s environment. 

• Crowdsourced vulnerability disclosures: Similar to bug bounties, except the security flaws are announced publicly rather than privately submitted. These disclosures sometimes include recommendations for how developers can fix vulnerabilities. 

Businesses often leverage several of these methods in their approach to mobile application security testing. For example, many organizations use automated tools to conduct the bulk of their testing, accompanied by manual reviews to address logic and intent and an ongoing bug bounty program for an added layer of security. Other complementary mobile application security tactics that may be used in tandem with MAST include threat modeling, compliance testing, and red team attack simulations. 

What tools can be used for mobile application security testing? 

The most frequently recommended tools for mobile application security testing are SAST, DAST, IAST, SCA, and fuzzing tools.

Here’s a quick rundown of each tool category: 

• Static application security scanning (SAST) tools scan application source code to identify vulnerabilities. These tools can run early in the CI/CD pipeline or even as an IDE plugin while coding. SAST is an example of “white box” testing, which means knowledge of the application’s internal design is taken into account.

• Dynamic application security testing (DAST) tools check security at runtime by testing common attack types against the running application. Because these tools require a functioning application, they can only be used much later in the development process. DAST is an example of “black box” testing, which means it is based on external assumptions only (internal knowledge of the application is not considered). 

• Interactive application security testing (IAST) tools check security at runtime via application scanning and analysis of internal application flows. IAST is a blend of white box and black box testing because it links DAST-like findings (e.g. identification of regressions) to source code as a SAST tool would. 

• Software composition analysis (SCA) tools track third-party code dependencies, which is useful for apps that incorporate many open source libraries. Developers can use these tools to discover all related appl components, their supporting libraries, and their direct and indirect dependencies, including vulnerabilities and possible exploits. 

• Fuzzing tools automatically inject invalid or unexpected inputs into an application to expose bugs. Fuzzing, a black box testing technique, is intended to overwhelm the application in an effort to cause unexpected behavior, crashes, or resource leaks. 

What are the common challenges in mobile application security testing?

Common mobile application security challenges include platform fragmentation, language coverage, difficulty sourcing mobile DAST, and defaulting to simulated tests. 

• Platform fragmentation occurs when an application is run across many different operating systems and devices. In some cases, security not only has to be tested across different platforms but also different versions of the same operating system (this is more common for Android as third-party manufacturers provide their own versions of the OS). 

• Language coverage can present a challenge when an organization’s MAST toolset does not support certain languages, especially platform-independent languages such as Java, Kotlin, Objective C, and Swift. With hybrid mobile apps, the security risks of native development are amplified by the risks of web applications.  

• Difficulty sourcing DAST tools is a common challenge because many testing frameworks are not geared toward mobile application security. While these frameworks are improving, it can still be difficult to get real-world data for mobile DAST. 

• Defaulting to simulated tests is a common developer practice due to convenience, however it is not a comprehensive testing method. While simulated testing is a good starting point, testing on actual devices is important for more accurate emulation of the user experience and real-world vulnerability scenarios. 

Mobile application security testing best practices 

While the exact details of MAST execution will depend on your organization and unique mobile application security strategy, some time-tested practices will help you overcome the common challenges mentioned above: 

• Incorporate MAST into your mobile CI/CD pipeline to realize the benefits of shift left security, such as improved security posture and integration, as well as speed and reduced costs. 

• Look to established security frameworks such as OWASP and the Mobile Security Testing Guide to help find common issues and leverage the extensive research that security experts have already conducted. 

• Use multiple testing methods such as SAST, DAST, and SCA. As discussed previously, different tests address different types of security issues and scenarios. 

• Continuously test mobile applications to identify new vulnerabilities. Just because an app was secure when you first built it doesn’t mean it still is today. 

• Develop with testing in mind by annotating code and widgets during the development process so that future testing, especially dynamic tests, are easier to manage. 

• Choose the right automated scanning tools with complementary features to ensure they fit well into your CI/CD pipeline, cover the necessary mobile app programming languages, and lower the total amount of false positives. 

• Don’t neglect the backend security of your mobile applications. Even if the front end app is secure, you need to ensure that all of the data it is connected to or using does not contain vulnerabilities. 

• Test across many different devices to account for the variety in phone components and consider using automation to make this process more efficient. 

As noted in the foreword of the Mobile Security Testing Guide, the best way to advance your MAST skills and ability to use MAST tools is through experience: “True excellence at mobile application security requires a deep understanding of mobile operating systems, coding, network security, cryptography, and a whole lot of other things.”

Strengthen your mobile application security testing with Snyk 

Looking to improve your MAST process? The Snyk platform provides a combined SAST and SCA mobile application security approach that allows developers and security teams to quickly find, prioritize, and fix security issues in their code as well as known vulnerabilities in open source dependencies. 

When automatic scans are shifted earlier in the development process, security is significantly improved before a mobile app gets into the hands of users. To learn more about shift left security and how MAST fits into an overarching testing strategy, check out our guide to application security testing.