Mobile application security testing (MAST)
Mobile devices are no longer just technology for making calls and sending messages; they have become a primary tool for managing both personal and work-related tasks. Today, it’s perfectly common to check bank accounts, communicate with colleagues, or access business systems directly from your phone. In many cases, mobile apps handle some of the most critical data we interact with on a daily basis.
This shift has been driven largely by remote work and a "mobile-first" mindset in modern software development. But greater convenience can also mean greater exposure. Mobile apps have become highly attractive targets for attackers, who seek to exploit weaknesses, steal information, take over sessions, or completely compromise devices.
As a basic preventive measure against these risks, organizations should implement mobile application security testing (MAST). This approach, as part of an AppSec solution, helps ensure that the software we use on mobile devices is more resilient to increasingly sophisticated attacks. MAST is not just another requirement to check off before releasing an app; it is a central component of any modern security strategy that seeks to protect a company’s reputation, its users' privacy, and, ultimately, its bottom line.
What is mobile application security testing?
MAST typically combines various techniques and tools to identify vulnerabilities, misconfigurations, and privacy issues in mobile applications throughout their lifecycle. This methodology differs from traditional web testing because it must account for the particularities of the mobile environment: operating systems (such as iOS and Android), a wide variety of devices, and platform-specific security mechanisms.
MAST assesses, for example, how an application handles data at rest and in transit, manages permissions, implements authentication, and communicates with backend services and third-party integrations. When MAST is viewed as a comprehensive approach to evaluating mobile applications (though we may sometimes refer to it simply as a technique for detecting vulnerabilities specific to mobile technology), it combines automated tools with manual analysis to provide a well-rounded view of their security posture. By scrutinizing an app from the "inside out" (analyzing the code) and the "outside in" (testing the running app), MAST helps developers identify and remediate flaws before anyone can exploit them.
Why is MAST essential for modern enterprises?
The necessity of MAST stems from the unique architecture and usage patterns of mobile devices. Organizations today are releasing and updating applications at a relentless pace to stay competitive, often prioritizing speed over security. This "rush to market" frequently leads to the inclusion of insecure code patterns or the use of unvetted third-party libraries.
The high value of mobile data
Mobile devices have access to sensitive features and data, such as cameras, microphones, location, and contact lists. They are also used as a key factor in multi-factor authentication (MFA), making them even more valuable from a security standpoint. If a mobile application is compromised, the attacker not only gains access to it but also potentially gains a foothold in users’ digital identities and the back-end infrastructure of the organizations to which the devices are linked.
The lack of environmental control
Unlike traditional web applications, which run on a server controlled by the organization, mobile applications run on devices that the organization does not control. These devices may be rooted or jailbroken, which removes many of the built-in security protections. On top of that, mobile apps are often used on untrusted networks, such as public Wi-Fi, where attackers can intercept traffic or attempt to carry out man-in-the-middle (MITM) attacks.
Regulatory and compliance requirements
With the implementation of strict data protection laws such as GDPR, HIPAA, and PCI DSS, the penalties for data breaches have become quite severe. As part of a comprehensive AppSec solution, MAST can provide the necessary documentation and validation to demonstrate that an organization has exercised due diligence in protecting users' confidential information, thereby avoiding substantial regulatory fines and legal liabilities.
How does MAST work?
Effective mobile security testing goes beyond a simple automated scan. It usually begins by understanding what the application does and how sensitive its data is. That context is vital because it determines where testers should focus their attention and what types of issues are most important to detect. From there, the assessment tends to follow these practical steps:
Preparation and decompilation: The first step is getting the app's binary (APK for Android or IPA for iOS). Since source code isn't always available, testers often have to reverse engineer the app to figure out how it behaves under the hood—what logic it follows, which APIs it exposes, and whether any secrets are embedded in the code.
Static analysis: This involves examining the decompiled code or the original source code without executing the app. The goal is to find unsafe coding patterns, insecure use of platform APIs, and flaws in the application's design.
Dynamic analysis: The application is executed in a controlled environment—ideally on a real device—to observe its behavior at runtime. Testers simulate attacks to see how the app handles network communication, local storage, and user authentication under "stress."
API and backend testing: Since mobile apps are essentially front-ends for complex backend services, MAST must include a rigorous assessment of the APIs. This ensures that an attacker cannot bypass the mobile client and attack the server directly.
Manual penetration testing: Automated tools are excellent for finding known patterns, but they often miss complex logical flaws. Human experts use the insights gained from previous steps to perform targeted, creative attacks that simulate the behavior of a real-world adversary.
Core techniques in the MAST arsenal
To achieve full coverage, MAST utilizes several distinct testing techniques, each offering different insights into the application's security.
Static application security testing (SAST)
SAST is a white-box testing approach, which means it analyzes the application from the inside by directly examining the code. This makes it useful for detecting issues early in the development cycle, even before the application is running. It is particularly effective at detecting issues such as hardcoded credentials, weak encryption options, or poor input validation. However, because it lacks runtime context, it can generate false positives or miss issues that only appear when the application interacts with the device’s hardware or the network.
Dynamic application security testing (DAST)
DAST is a black-box testing method that interacts with the running application. It focuses on the "outside" view, looking for runtime vulnerabilities like flawed session management, insecure data transmission, and authentication bypasses. DAST is essential for understanding how the app behaves in the real world, though it cannot pinpoint the exact line of code responsible for a flaw.
Interactive application security testing (IAST)
IAST acts as a hybrid approach. It uses software agents or sensors embedded within the application to monitor its behavior in real-time. IAST combines the strengths of SAST and DAST, providing high accuracy with the benefit of identifying the specific code responsible for a runtime vulnerability.
Software composition analysis (SCA)
Modern apps are rarely written from scratch; they rely heavily on open-source libraries and third-party SDKs (software development kits). SCA tools scan these components to identify known vulnerabilities and licensing risks. This is a critical part of securing the software supply chain, as a single vulnerable library can compromise the entire application.
The OWASP Mobile Top 10: understanding the risks
The Open Worldwide Application Security Project (OWASP) maintains the Mobile Top 10, a definitive list of the most critical security risks facing mobile applications. Understanding these risks is essential for any developer or security professional. Here is a brief overview:
M1: Improper Credential Usage: This occurs when applications use hardcoded passwords or store credentials in insecure locations on the device. Attackers can extract these secrets from the binary or device storage to gain unauthorized access to backend systems.
M2: Inadequate Supply Chain Security: This risk involves the use of vulnerable third-party libraries or compromised development tools. If a developer uses a malicious SDK, the entire app becomes a vehicle for malware or data theft.
M3: Insecure Authentication/Authorization: In some applications, authentication and access control aren't enforced as strictly as they should be. Weak password requirements or missing checks around user identity can open the door to unauthorized access. In more serious cases, this can allow users to perform actions beyond their intended permissions, including gaining elevated privileges.
M4: Insufficient Input/Output Validation: Input handling is another area where small oversights can turn into big problems. If an application doesn't properly validate what it receives or what it sends back, it can open the door to injection attacks like SQLi or XSS. From there, it's possible to interfere with database queries or execute unintended code inside the app.
M5: Insecure Communication: Problems often arise when applications don't properly protect data in transit. If encryption is weak—or missing altogether—or if mechanisms like certificate pinning aren't in place, it becomes much easier for attackers to intercept and read network traffic.
M6: Inadequate Privacy Controls: Many applications collect more personal data than they actually need. When that information isn't carefully managed or protected, it increases the chances of privacy issues and can put organizations at risk of failing to meet regulatory requirements.
M7: Insufficient Binary Protections: If an application is not properly obfuscated or protected against tampering, attackers can reverse-engineer the code to find vulnerabilities or create "malware-laden" versions of the app to redistribute.
M8: Security Misconfiguration: This involves using default settings, leaving debug modes active in production, or granting the app excessive permissions. These oversights provide easy entry points for attackers.
M9: Insecure Data Storage: Some applications still store sensitive information in plain text—whether in local files, databases, or even logs. That might not seem like a big deal at first, but it becomes one quickly if the device is lost, stolen, or compromised by another app. In those situations, that data is basically up for grabs.
M10: Insufficient Cryptography: Cryptography issues usually come down to poor choices or poor implementation. That could mean relying on outdated algorithms or just using them incorrectly. Either way, if the protection is weak, the data behind it isn't protected at all.
Key challenges in mobile testing
Conducting MAST is significantly more complex than testing traditional desktop or web software due to several industry-specific challenges:
Platform fragmentation: Developers must ensure their applications are secure across hundreds of different device models and multiple versions of Android and iOS. Security features that work on the latest OS version may be absent or broken on older ones.
Language and framework diversity: Mobile applications aren't built in just one way. Teams use different languages—like Java, Kotlin, Swift, or Objective-C—and often rely on cross-platform frameworks such as React Native or Flutter. That variety makes testing harder, especially when you're trying to rely on a single tool to cover everything.
Simulators vs. real devices: Emulators and simulators are great for quick checks, especially during early development. But they don't always behave like real phones. Certain things, like how secure storage works on actual hardware or how the app deals with unstable networks, can be hard to reproduce. At some point, you need to test on real devices to see what's actually going on.
The "Man-at-the-End" (MATE) attack: In the mobile world, the attacker can have physical possession of the device and its software. This gives them unlimited time to use specialized tools to inspect, reverse engineer, and modify the application's binary.
MAST best practices
To build a truly secure mobile application, security cannot be an afterthought; it must be integrated into every stage of the development lifecycle.
Incorporate MAST into CI/CD: Automate security scans so that every code commit or build is checked for vulnerabilities. This allows for "shift-left" security, where issues are found and fixed when they are least expensive to remediate.
Use multiple testing methods: There's no single tool that will catch everything. In practice, you need a mix of SAST, DAST, and SCA, along with manual testing, to get a clearer picture of what’s happening across both the code and the running app.
Adhere to standards: It also helps to anchor your testing against well-known frameworks like OWASP MASVS and MASTG. They give you a solid reference point and make it easier to check whether your security controls are actually doing what they’re supposed to.
Don't ignore the backend: A secure mobile frontend is useless if the backend APIs are vulnerable. Always include the server-side components in your testing scope.
Continuous monitoring: Security is not a one-time event. New vulnerabilities are discovered daily; therefore, applications must be continuously assessed, even after they have been released to the App Store or Google Play.
What to look for in a MAST provider
When selecting a partner or a toolset for mobile security, organizations should look for providers that offer more than just a list of generic findings. A top-tier MAST provider should offer:
Deep mobile expertise: The provider should have a proven track record of testing both iOS and Android apps, with a deep understanding of platform-specific vulnerabilities.
Low false positive rates: Automated tools can be "noisy." A good provider uses manual verification to ensure that every reported vulnerability is a legitimate risk, saving your developers from wasting time on non-issues.
Actionable remediation advice: Knowing a vulnerability exists is only half the battle. Your MAST reports should include clear, contextual guidance on how to fix specific lines of code or configuration flaws.
Seamless integration: The solution should integrate directly into your developers' existing workflows (IDEs, Jira, GitLab) so that security becomes a natural part of their day-to-day work.
Fluid Attacks: a comprehensive approach to MAST
At Fluid Attacks, we’ve seen firsthand that automation on its own doesn’t go far enough when dealing with complex mobile environments. That’s why our MAST approach is just one part of our comprehensive Continuous Hacking solution, in which automated testing is combined with the knowledge and creativity of human experts.
While we typically refer to MAST as a technique for detecting unique vulnerabilities in mobile environments, we offer a comprehensive solution that combines SAST, DAST, and SCA with manual penetration testing conducted by highly certified pentesters (with credentials such as eMAPT, GMOB, and CMPen-iOS/Android) to ensure the security of your mobile applications. Our solution goes beyond what traditional scanners can detect to identify complex logical flaws and zero-day vulnerabilities that could have a critical impact on your business.
Our platform gives you a clear, centralized view of your security posture, so you can focus on the vulnerabilities that actually matter. It also uses AI to suggest ways to fix issues, helping teams address problems more quickly instead of getting stuck figuring out next steps. Whether you are a small startup or a large enterprise, Fluid Attacks helps you protect your mobile applications from the very first line of code and beyond, even after they've been released to the market.
The future of MAST: AI and automation
The field of mobile security is rapidly evolving. We are seeing a move toward AI-enhanced analysis that can predict potential vulnerabilities before they are even written. New approaches—especially those using machine learning—are starting to improve how accurately tools like SAST and DAST detect real issues, cutting down on noise along the way (see our AI SAST). As mobile apps continue to connect with IoT devices and rely more on things like biometrics, the need for robust security testing will become even more critical.
Conclusions
Mobile application security testing is an indispensable requirement for any organization that values its data and its users' trust. By providing deep visibility into an application's code and its runtime behavior, MAST enables organizations to find and fix vulnerabilities before they can be exploited.
Challenges like platform fragmentation or advanced reverse engineering are definitely part of the landscape, but they’re manageable with the right approach. Bringing security earlier into the development process, following standards like OWASP MASVS, and involving people who can go beyond automated tools all make a noticeable difference in how secure an application ends up being. Investing in MAST is an investment in your company's long-term resilience and reputation in a mobile-driven world.
If you’re ready to secure your mobile applications with our MAST, SAST, DAST, and SCA tools, we invite you to sign up for our 21-day free trial. For organizations seeking the highest level of security, our team of penetration testing experts is ready to help you overcome your most complex security challenges. Contact us today to learn more.
