Mobile apps have become an important part of everyday life. People use them for shopping, banking, communication, healthcare, education, entertainment, and business. As mobile apps handle more personal and business information, security has become an important part of the development process.
A mobile app can have a great design and useful features, but a security weakness can put user accounts, personal information, payment details, and business data at risk. Security should therefore not be treated as something to check only before an app is launched. It needs to be considered from the planning and development stages through testing, deployment, and regular updates.
The OWASP Mobile Application Security Verification Standard (MASVS) provides a useful security baseline for mobile applications. It covers areas such as secure data storage, cryptography, authentication, network communication, platform interaction, code quality, resilience, and privacy.
Why Mobile App Security Matters
Mobile applications often collect and process sensitive information. Depending on the type of app, this can include names, email addresses, phone numbers, passwords, location information, payment details, business records, or other private data.
A security problem can result in unauthorized account access, data exposure, fraud, service disruption, or loss of customer trust. Mobile apps also communicate with APIs, databases, cloud services, third-party SDKs, and other systems, so security needs to cover the complete application environment rather than just the mobile interface.
For this reason, developers should identify possible risks early and build security controls into the application architecture.
1. Plan Security Before Development Starts
One of the simplest ways to improve app security is to think about security before writing the code.
Start by identifying:
- What information will the app collect?
- Which data is sensitive?
- Where will the data be stored?
- Which APIs will the app communicate with?
- Who can access different features?
- What happens if a user’s device is lost?
- What could happen if an account is compromised?
- Which third-party services or SDKs will be used?
Threat modeling can help development teams understand how an application could be attacked and which parts require stronger protection. OWASP recommends treating secure architecture, design, and threat modeling as foundations for mobile application security.
2. Protect Sensitive Data on the Device
Mobile applications sometimes store information locally to improve performance or support offline functionality. However, sensitive information should not be stored carelessly.
Developers should avoid keeping passwords, authentication tokens, payment information, or other sensitive data in plain text.
Use secure storage mechanisms provided by the operating system whenever possible. Where supported by the device, hardware-backed security features can provide additional protection.
It is also important to check other places where information may accidentally appear, such as application logs, cached files, backups, screenshots, or temporary storage.
OWASP’s mobile security guidance specifically treats secure storage and privacy as major areas of mobile application security.
3. Use Strong Authentication
Authentication confirms that a user is who they claim to be. Weak authentication can make it easier for attackers to gain access to user accounts.
Depending on the application, developers can use secure password policies, multi-factor authentication, biometric authentication, or other appropriate authentication methods.
However, authentication alone is not enough. The application should also manage sessions securely and prevent unauthorized users from continuing to access an account after a session expires or credentials are revoked.
For applications handling sensitive information, stronger authentication controls should be considered based on the application’s risk level.
4. Implement Proper Authorization
Authentication and authorization are not the same thing.
Authentication answers:
“Who is the user?”
Authorization answers:
“What is this user allowed to access?”
For example, an employee may be allowed to view their own profile but should not automatically have access to another employee’s private information.
Authorization checks should be implemented on the backend rather than relying only on the mobile application. This is important because attackers can modify or reverse engineer client-side code.
Every sensitive API request should verify whether the authenticated user actually has permission to perform the requested action.
5. Secure Network Communication
Mobile apps frequently communicate with backend servers and APIs. If this communication is not properly protected, sensitive information could potentially be exposed during transmission.
Use HTTPS with properly configured TLS for communication between the application and its servers. Developers should avoid sending sensitive information through insecure connections.
API endpoints should also use appropriate authentication and authorization controls.
Network security should be tested rather than assumed. OWASP MASVS includes secure network communication as one of its core security control areas.
6. Protect API Endpoints
A secure mobile application also depends on secure backend APIs.
Even if the mobile application itself looks secure, poorly protected APIs can expose important data or functionality.
API security should include:
- Strong authentication
- Proper authorization
- Input validation
- Rate limiting where appropriate
- Secure error handling
- Protection against injection attacks
- Proper session and token management
- Monitoring of suspicious activity
Never assume that an API request is safe simply because it comes from your mobile application. Treat data received from the client as untrusted input.
OWASP recommends validating and sanitizing untrusted inputs because application data can come from the UI, network, files, inter-process communication, and other sources.
7. Validate All User Input
User input should always be treated carefully.
Inputs can come from login forms, search fields, file uploads, deep links, API responses, and other sources. If input is processed without proper validation, it can contribute to security problems such as injection attacks or unsafe data handling.
Developers should validate data according to what the application actually expects and reject unexpected or invalid input.
Input validation should be performed on the server as well as the client where appropriate. Client-side validation improves user experience, but it should not be considered a security boundary.
8. Use Cryptography Correctly
Encryption can help protect sensitive information, but simply adding encryption does not automatically make an application secure.
Developers should use established cryptographic libraries and recommended algorithms instead of creating their own encryption methods.
Cryptographic keys also need to be handled carefully. A strong encryption algorithm is not useful if its keys are exposed or stored insecurely.
OWASP identifies cryptography as a dedicated mobile security control area and recommends using current cryptographic practices and appropriate implementations.
9. Be Careful With Third Party SDKs
Modern mobile applications often depend on third-party libraries and SDKs for analytics, payments, advertising, authentication, maps, communication, and other features.
These dependencies can save development time, but they can also introduce additional security risks.
Before adding an SDK, developers should consider:
- Who maintains it?
- Is it regularly updated?
- What permissions does it require?
- What data does it collect?
- Does it communicate with external servers?
- Does it contain known security issues?
- Is it actually necessary for the application?
Keeping dependencies updated and removing unnecessary libraries can reduce the application’s attack surface.
10. Minimize App Permissions
Mobile operating systems provide permission controls for features such as the camera, microphone, contacts, location, files, and notifications.
An application should request only the permissions it genuinely needs.
For example, a simple note-taking application may not need continuous access to a user’s location or contacts.
Reducing unnecessary permissions limits the amount of sensitive information an application can access and supports better privacy practices. OWASP’s current MASVS includes privacy controls focused on minimizing access to sensitive data and resources and providing transparency and user control.
11. Keep Sensitive Information Out of Logs
Developers often use logs to troubleshoot application problems. However, logs can accidentally contain sensitive information.
Avoid logging:
- Passwords
- Authentication tokens
- Payment information
- Personal information
- Private API keys
- Other confidential application data
Production logging should be carefully reviewed so that debugging information does not become a source of data exposure.
12. Make the App Resistant to Reverse Engineering
Mobile applications are distributed to user devices, which means attackers may be able to inspect the application package and analyze its code.
For applications with valuable intellectual property or sensitive client-side functionality, additional protections may be appropriate.
Depending on the threat model, developers can consider techniques such as code obfuscation, tamper detection, and other resilience measures.
These techniques should be treated as additional layers of protection rather than a replacement for fundamental security controls. OWASP separates resilience against reverse engineering and tampering from its core security controls for this reason.
13. Test the Application for Security Issues
Security testing should happen throughout development instead of waiting until the final release.
A security testing process can include:
- Static code analysis
- Dependency checks
- API security testing
- Dynamic application testing
- Authentication and authorization testing
- Network security testing
- Input validation testing
- Penetration testing
- Manual security reviews
OWASP provides the Mobile Application Security Testing Guide (MASTG) alongside MASVS to help security professionals and development teams test mobile applications against defined security requirements.
14. Secure the Development and Release Process
Mobile app security does not end when the code is completed.
Development teams should also protect the software development process itself. Source code repositories, build systems, signing keys, deployment credentials, and CI/CD pipelines should be properly secured.
Application signing credentials are particularly important because unauthorized access to them can create serious risks.
Teams should also maintain a controlled release process and ensure that production builds do not contain unnecessary debugging features or development credentials.
15. Keep the App Updated
Security threats change over time. New vulnerabilities can be discovered in operating systems, libraries, SDKs, frameworks, and backend services.
A secure app therefore needs ongoing maintenance.
Developers should monitor dependencies, update vulnerable components, review security reports, and release fixes when necessary.
Regular updates are also important when platform security requirements change.
A Simple Mobile App Security Checklist
Before launching a mobile application, development teams can review the following:
| Security Area | What to Check |
| Data Storage | Sensitive information is stored securely |
| Authentication | Users are properly authenticated |
| Authorization | Users can access only permitted resources |
| Network | Communication uses secure protocols |
| APIs | Endpoints are protected and validated |
| Input | Untrusted data is validated and sanitized |
| Cryptography | Current and trusted cryptographic methods are used |
| Permissions | Only required permissions are requested |
| Third Party SDKs | Dependencies are reviewed and maintained |
| Logs | Sensitive information is not exposed |
| Testing | Security testing is performed before release |
| Privacy | Data collection is minimized and explained |
| Updates | Vulnerabilities and dependencies are regularly reviewed |
Final Thoughts
Mobile app security is not a single feature that developers can add at the end of a project. It is an ongoing process that starts with architecture and continues through development, testing, deployment, and maintenance.
Developers should protect sensitive data, use secure authentication and authorization, protect APIs, secure network communication, validate user input, review third-party dependencies, limit permissions, and regularly test the application.
Using a recognized framework such as the OWASP MASVS can give development teams a structured way to review important areas of mobile application security. It provides a baseline, but it does not guarantee that an application is completely secure. Security controls should still be selected according to the application’s specific risks, users, data, and business requirements.
For businesses planning to build a new mobile application or improve the security of an existing one, taking a security-first approach can help create a more reliable application and reduce avoidable security risks over time.
