Approach towards Android Penetration Testing
~Darpan Patel & Pon Enock, Jan 9, 2025
Mobile penetration testing involves enhancing the security of the android device application by vulnerability assessment. Mobile pen testing involves security audit of binary files, source code of the android application, and network analysis. Mainly there are two types of penetration testing scenarios one is static analysis and other one is dynamic analysis.
Static analysis: Static analysis contains the analysis of source code by different tools and methods.
Dynamic analysis: Dynamic analysis refers to the testing of live applications.
Why is Mobile penetration testing needed?
Mobile application penetration testing is essential for several reasons:
Mobile applications are complex software systems that can contain numerous security vulnerabilities. Penetration testing helps identify these vulnerabilities, such as insecure data storage, input validation flaws, authentication issues, and insecure communication protocols.
- Protecting User Data
- Preventing Malicious Exploitation
- Compliance Requirements
- Maintaining Reputation
- Securing Backend Systems
Approach of mobile application penetration testing
When conducting mobile application penetration testing, it is crucial to follow a structured methodology to ensure the process is reliable and comprehensive. Here is a suggested methodology for the same.
1. Planning & Preparation
During the planning and preparation phase of mobile application penetration testing.It is essential to create a detailed plan tailored to your specific application. This plan should define the scope, establish timelines, and estimate the duration required for testing.
- Set clear goals
- Identify boundaries(in-scope/out-scope functions)
- Resource allocation
2.Reconnaissance
During reconnaissance gather information about your target as much possible there are mainly two techniques to gather information about your target:
- Active reconnaissance:Engage with the application to gather more in-depth information, such as performing API mapping and understanding the application’s logic.
- Passive reconnaissance:Collect information without interacting directly with the application for example use google dorking to gather information about your target you can also use shodan or censys.
3.Static application testing
Static application Security testing (SAST) is a crucial part of ensuring the security and stability of an application. It involves analyzing an application’s code, resources, and configuration files without executing the application. This type of analysis is typically performed by examining the application’s source code or its compiled binary file (APK) using tools like APKtool, dex2jar, and others. The goal of static analysis is to identify potential vulnerabilities in the code, such as insecure coding practices, data leakage, or hard-coded credentials
Key Aspects of Static Application Testing
- Code Analysis:
- Review the source code or decompiled code to identify security flaws, such as SQL injection, buffer overflows, and cross-site scripting (XSS).
- Look for hard-coded credentials, API keys, and sensitive information within the code.
- Ensure secure coding practices are followed, such as proper error handling and input validation.
- Resource and Configuration File Analysis:
- Examine configuration files for security misconfigurations. This includes checking for improper permissions, insecure network configurations, and sensitive data exposure.
- Analyze resource files to ensure no sensitive information is inadvertently included.
- Android Manifest File Analysis:
- The Android Manifest file is crucial as it contains information about the application, including its package name, version number, required permissions, and components such as activities, services, and broadcast receivers.
- Verify that only necessary permissions are requested. Excessive permissions can lead to security risks if the application is compromised.
- Check for exported components that might be unintentionally exposed to other applications, leading to potential data leakage or unauthorized access.
- Security Controls and Root Detection:
- Ensure that the application implements proper security controls to protect sensitive data and functionality.
- Root Detection: Verify that the application includes mechanisms to detect if the device has been rooted. Rooted devices can bypass security restrictions, allowing malicious apps to exploit the application. This can be done by checking for the presence of su binary, known rooting apps, or abnormal file system modifications.
Tools for Static Application Testing
- APKtool: Used for decompiling and recompiling Android application packages (APKs), allowing for easy inspection of the application’s resources and manifest file.
- dex2jar: Converts .dex files to .jar files, making it possible to use Java decompilers to analyze the application’s code.
- Java Decompilers: Tools like JD-GUI or JADX can be used to view the decompiled source code of the application.
By incorporating these steps and utilizing the appropriate tools, static application testing can effectively identify and mitigate potential vulnerabilities, ensuring the security and reliability of the application before it is deployed.
During the static analysis of the application you must check the android manifest file. which contains information about the application, including its package name, version number, required permissions, and components such as activities, services, and broadcast receivers.
You can use Jadx,mobsf tools for doing static analysis of the application code.
4.Reverse Engineering
Reverse engineering involves deconstructing an application to analyze its code, understand its functionality, and identify potential security vulnerabilities. This process is particularly useful when you do not have access to the original source code, as it allows you to inspect the binary or Dalvik code. Various tools and techniques can assist in reverse engineering, such as decrypting the code from dex to jar to Java, using tools like APKtool for decompiling and analyzing the APK file.
Tools for Reverse Engineering
- APKtool: Decompiled APK files to reveal the resources and manifest files, allowing for modification and analysis.
- dex2jar: Converts .dex files (Dalvik Executable) to .jar files, making them readable by Java decompilers.
- Java Decompilers: Tools like JD-GUI or JADX can be used to decompile the .jar files back to Java source code for easier analysis.
What to Check in the Code
- Permissions:
- Excessive Permissions: Ensure the application only requests necessary permissions. Excessive permissions can increase the attack surface.
- Dangerous Permissions: Verify that permissions classified as “dangerous” are genuinely required for the application’s functionality. These include access to contacts, SMS, storage, location, and more.
- Permission Handling: Check how the application handles permission requests and responses. Ensure it gracefully handles denied permissions without crashing or exposing vulnerabilities.
- Sensitive Data Handling:
- Data Storage: Examine how sensitive data (such as user credentials, personal information, and financial data) is stored. Ensure data is encrypted both in transit and at rest.
- Data Exposure: Look for any hard-coded sensitive data within the code, such as API keys, passwords, or tokens.
- Input Validation:
- Sanitization: Ensure all user inputs are properly sanitized and validated to prevent injection attacks (e.g., SQL injection, XSS).
- Boundary Checking: Validate inputs for expected formats, lengths, and ranges to prevent buffer overflow and other similar attacks.
- Authentication and Authorization:
- Authentication Mechanisms: Analyze the authentication process to ensure it is secure. This includes checking for weak passwords, improper session management, and vulnerabilities in login mechanisms.
- Authorization Checks: Verify that the application properly enforces authorization checks to prevent unauthorized access to sensitive features or data.
- Data Storage:
- Secure Storage: Ensure that sensitive data is stored securely, using encrypted storage mechanisms like the Android Keystore.
- Data Retention: Check how long sensitive data is retained and ensure it is properly deleted when no longer needed.
- Network Communication:
- Encryption: Ensure that all network communications use secure protocols (e.g., HTTPS) to encrypt data in transit.
- Certificate Pinning: Implement certificate pinning to prevent man-in-the-middle (MITM) attacks.
- Third-Party Libraries:
- Library Security: Evaluate the security of third-party libraries used by the application. Ensure they are up-to-date and do not contain known vulnerabilities.
- Licensing and Compliance: Verify that the use of third-party libraries complies with licensing requirements and does not introduce legal risks.
- Security Features:
- Root Detection: Implement root detection to identify if the device has been rooted, which could compromise the application’s security.
- Tamper Detection: Include mechanisms to detect if the application has been tampered with, such as checking for changes in the APK signature.
- Cryptography:
- Algorithm Strength: Ensure that cryptographic algorithms used are strong and up-to-date (e.g., AES-256 for encryption).
- Key Management: Verify that cryptographic keys are managed securely, using mechanisms like the Android Keystore to store keys securely.
By thoroughly analyzing these aspects during the reverse engineering process, you can identify and address potential security vulnerabilities, ensuring the application is robust and secure.
5.Dynamic Application Testing.
Dynamic application testing involves analyzing the application by executing it and observing its behavior in real-time. This type of testing focuses on identifying vulnerabilities that arise during runtime, such as insecure data transmission, improper session management, and other common issues.
- API and Login Flow Testing:
- API Testing: Test the application’s APIs to ensure they handle requests securely and validate inputs correctly. Check for issues such as broken authentication, excessive data exposure, and lack of rate limiting.
- Login Flows: Verify that login mechanisms are secure. This includes checking for weak password policies, proper session management, and protection against brute force attacks.
- Intercepting Requests:
- Use tools like Burp Suite or OWASP ZAP to intercept and analyze the HTTP/HTTPS traffic between the application and the server.
- Inspect the requests and responses to identify potential vulnerabilities such as sensitive data exposure, lack of encryption, and insecure cookies.
- Vulnerability Testing:
- Test for common vulnerabilities such as SQL injection, cross-site scripting (XSS), cross-site request forgery (CSRF), and insecure direct object references (IDOR).
- Ensure that error messages do not reveal sensitive information that could be exploited by attackers.
- OWASP Mobile Application Security Checklist:
- Refer to the OWASP Mobile Application Security Checklist, which provides comprehensive guidelines for dynamic application testing.
- This checklist covers various aspects such as network communication, authentication, authorization, data storage, and more.
- Setting Up a Proxy Listener:
- To effectively perform dynamic analysis, set up a proxy listener to capture and analyze the traffic between the application and the server.
- Configure the mobile device or emulator to route traffic through the proxy tool. This setup allows you to monitor and manipulate the traffic to identify potential security issues.
- Runtime Analysis:
- Monitor the application’s behavior during runtime to detect issues such as memory leaks, improper error handling, and insecure use of third-party libraries.
- Use tools like Frida or Xposed Framework to hook into the application and analyze its internal behavior.
Tools for Dynamic Application Testing
- Burp Suite: A powerful tool for intercepting and analyzing HTTP/HTTPS traffic. It includes features for scanning and identifying vulnerabilities in web applications.
- OWASP ZAP: An open-source web application security scanner that helps find security vulnerabilities in web applications.
- Frida: A dynamic instrumentation toolkit for developers, reverse-engineers, and security researchers.
- Exposed Framework: A framework that allows you to modify the behavior of the system and apps without modifying any APKs.
By conducting thorough dynamic application testing, you can uncover vulnerabilities that only manifest during runtime, ensuring a more secure and robust application deployment.
6.Report generation
After completing all the processes, you have to create a detailed report about your work. The report must be designed so that both technical and non-technical people can understand it. Additionally, if a third person who is not aware of the process comes into the picture, they should be able to gain knowledge about the application just by reading your report.
Conclusion
Mobile application penetration testing is a critical step in ensuring the security and reliability of Android applications. By following a structured approach that includes both static and dynamic analysis, organizations can effectively identify and mitigate potential vulnerabilities.
Ultimately, mobile penetration testing not only protects user data and maintains application integrity but also helps organizations comply with regulatory standards and uphold their reputation. By documenting findings in a clear, comprehensive report, stakeholders can make informed decisions about addressing vulnerabilities and enhancing application security.
Investing in mobile penetration testing is an investment in user trust, compliance, and long-term success in the ever-evolving digital landscape.