Mobile App Penetration Testing: 9 Best Practices for Robust Security

Over 100,000 new mobile apps are released monthly, some of which users access an average of 11 times per day. These statistics bode well for the companies that build these apps. However, unchecked over time, apps could present vulnerabilities that hackers can exploit. Moreover, a data breach resulting from a hack can lead to hijacked accounts and financial fraud for app users.  Meanwhile, for the attacked business, it could mean lost revenue, reputational damage, and data privacy fines.

Companies can pre-empt and prevent data breaches with mobile app penetration testing. With regular, scheduled penetration testing, you take an offensive stance in your mobile application security testing approach. The idea behind regular, scheduled pen testing is to move beyond reactive security, where cybercriminals discover vulnerabilities in your mobile apps before you do. Instead, you hire ethical hackers to uncover weaknesses so that you can fix vulnerabilities before cybercriminals have a chance to identify and exploit them.

In this blog, we will discuss critical mobile app security testing best practices you can apply to safeguard your apps.

9 Best Practices in Mobile App Pentesting

1. Chalk out a thorough pentesting strategy

Before diving into pentesting, you need to define the goals and scope of what you will test. This includes not just listing in-scope test scenarios, but also creating a hierarchy or chronology. At this point, you would typically consider which scenarios are linked to higher risks, compliance, or client mandates and prioritize these over others.
If you’re still figuring out your way around this, look to scan and test for the top vulnerabilities cited by OWASP or Nessus.  You might want to consult this helpful resource before getting started.

2. Put SAST, DAST, and IAST methods to work

The goal of your pentesting exercise is to uncover as wide a range of vulnerabilities as possible and remediate these as quickly as possible. This means that you want to inspect the app’s source code, and also test your mobile apps while they are running. Whitebox mobile app penetration testing tools like Static Application Security Testing (SAST) and Blackbox tools like Dynamic Application Security Testing (DAST) allow you to achieve these goals, respectively. But these come with their limitations — DAST does not inspect code.

SAST calls for unique tools for every language used, and it cannot grasp frameworks like API. A third type of mobile app penetration testing tool, Interactive Application Security Testing (IAST), makes up for the gaps in the earlier two methods but cannot stand alone because it only tests the part of the application that runs during the test. Consequently, mobile app security testing efforts should involve all three tools to uncover a larger range of vulnerabilities.

3. Layer your file analysis and testing

Layered app architecture calls for layered analysis of all associated files to categorize them as benign or trusted, authorized, sensitive, and so on. While tedious, this type of mobile app penetration testing-linked analysis helps you test against and prevent the most common hacking technique, SQL injection. By testing files proactively, hackers struggle to interfere with queries sent by the files in your architecture.

4. Verify encryption adherence

Look for bugs, errors, and other weaknesses in your mobile app’s encryption code, configuration, and even its logic. Your mobile app penetration testing process should also check that your mobile app is not using outdated or deprecated encryption codes and standards. Ideally, you want encryption keys to be secured in the app’s sandbox or a cloud-based vault, but if encryption keys are embedded in app code (which isn’t ideal), you should test how easy it is for it to be reverse-engineered.

5. Test and fine-tune authentication and authorization

It is critical for your mobile app pentesting to also check for possible breaches linked to access control guardrails. Test if defenses are working as they should across password and token-based authentication, role, and attribute-based access control mechanisms.

6. Simulate the correct test environment

Dedicate at least one host for your mobile app pentests to avoid disrupting your test environment. You can achieve this by cloning an existing host, thereby creating a realistic target for various attacks without the risk of environmental compromise.  Make sure your testing mirrors real-world threats — basic actions like file encryption or copying won't adequately test a vulnerability. Your tests must identify genuinely malicious behavior, like ransomware or data exfiltration. That’s also why it is critical to use a cloned system. Live malware testing can be a reliable way to get an accurate assessment of your security posture. Your mobile app penetration testing should consider device-based differences. Lastly, don’t forget to have unique penetration testing for Android and iOS app versions security. 
Pro tip: You might even want to try working social engineering into your simulation.

7. Don’t overlook server attacks

Ideally, your mobile and web application servers should have defenses in place that protect them against DoS and DDoS attacks that attempt to overload them with traffic. You need to test how these defenses — whether you’re using rate limiting, web firewalls, network diffusion, or all of the above — hold up in such a scenario. Your mobile app pentesting must incorporate unlimited file upload, open redirect, and cross-origin resource sharing.

8. Harness generative AI to test at scale

If you’re pentesting sporadically instead of with every mobile app version, and at regular intervals, before malicious actors have the chance to exploit mobile app vulnerabilities, why are you testing at all? Penetration testing should uncover vulnerabilities and prioritize these by impact so that you can remediate them. When you apply AI to pentesting, you can test at scale and choose top-priority threats for validation. With a smaller, more focused set of fixes as your checklist, you are automatically better placed to secure your mobile applications against risks that matter to your clients, regulators, and your unique context. Moreover, you act faster — generative AI can cut your pentesting timelines from three weeks to a few minutes. This way, you can test regularly, instead of sporadically.

9. Improve pentesting validation practices with PTaaS support

This is not so much a technical tip, as it is about an approach to mobile app pentesting. A number of threats go unaddressed because when the time comes, you are unable to replicate the testing scenario — and when you try to contact the vendor involved, you might not be able to get hold of them. They’ve submitted their PDF of findings and moved on to the next project. In contrast, when you work with a reliable PTaaS platform partner, you can count on live or async support on such matters. Live support might include a phone call and/or email conversations with experts; Async support includes video evidence of how the vulnerability was uncovered.

Make Practical Improvements to Your Pentesting Schedule with Siemba

Conducting a rigorous & regular mobile app pentesting regime and adhering to the best practices outlined in this blog can be expensive, time-consuming, and unrealistic, especially if you have multiple app releases at the same time or in quick succession. That’s where Siemba can jump to your rescue. With Siemba, you can speed up, scale, and improve your mobile app pentesting, and save 90% of your team’s bandwidth, while also successfully hardening your security posture. 

Secure your mobile apps, reputation, and business resilience with Siemba. Contact us now to get a free demo, learn about our flexible engagement models, and find out how businesses like yours use Siemba for reliable offensive security.