Android App Security Best Practices (2024 Guide)

Security breaches on mobile devices cost trillions of dollars, causing businesses to suffer trillions in losses today. A single security breach can lead to the death of a company owing to loss of trust and legal repercussions. Android developers today must implement the highest possible levels of security measures to protect their apps from existing and evolving threats.

Regulators in many jurisdictions worldwide are implementing stricter standards in data protection. A reputation for high-security standards can give a company an edge over its competitors. Therefore, there is an incentive to implement world-class security measures. This post highlights the best practices in Android app security implementation.

HTTPS Network Connections

A lot of security breaches happen when data is in transit. Important details such as login credentials and financial information, are targeted at this point. By using a HTTPS protocol for network connections, a developer is assured of encryption of all data passing between the app and the server.  If there are any hard-coded links in your app, they should all be updated to rely on the HTTPS protocol. This way, you can build trust in your app among the customer community. It is also crucial to have an SSL certificate for the application.

Secure Authentications

Today there are numerous options developers can choose to strengthen the authentication process on their app. The first option is to implement two-factor authentication where a user first enters their password, which triggers the app to send a code sent as a text message or an email. The user is requiring entering the code before gaining access to the app. Biometric authentication could also help to increase the security of an app while also smoothing out the user access process because it is faster than two-factor authentication.

Android Application Sandbox

The Android Application Sandbox environment allows containerization of apps to they do not interact or share resources. Each app has a unique ID with specific privileges and limited interaction with the operating system. The environment also allows for auditing of every app’s activity  for detection of suspicious activity.

When building an app, developers must ensure the app data is not available to the ‘world’. In situations where an app needs to share data with another app, the use of a content provider would be a better implementation. Developers should follow existing guidelines for sharing different file types within the Android sandbox environment.

Carrying Out Proper Testing

Before an app is published, the development team should conduct rigorous testing both manually and with the use of automated tests. Automated tests can be done to help assess the overall vulnerability of the app and the recommended fixes. Penetration testing can be done by an ethical hacker to test how well an app can withstand threats such as social engineering. Experienced development teams are well placed to pre-empt the nature of threats an app can based on the nature of information it will access normal use.

Least Privilege

In cases where an app requires access to sensitive information or other features on user devices, the app should request access to only what is necessary. The least privilege approach minimizes the risk of information leakage. It is also best practice to activate runtime permissions, whereby an app expressly requests a user to grant access via a pop window on the screen.  Developers should be keen to explain clearly why the app requires such permissions. UI writers can help write the right copy to avoid over complicating the app for users.

Safe Code Practices

The choice of an untrusted API can easily compromise the integrity of an application. Developers must use trustworthy APIs in their projects.

Another best practice is to validate user input because they are a regular source of malware attacks. Input validation involves checking the format, length, and type of input data coming from users to ensure it matches what is expected. Sanitizing user input is equally as important as validating it.

Implementing role-based access helps to limit access to sensitive data on an app based on user roles. The creation of roles and privileges has to be well-thought-out during the design phase of app creation.

Third-Party Libraries

While third-party libraries are great for faster and easier functionality implementation, they should be used with caution. Developers should rely on libraries with good documentation and a strong user community where issues around security vulnerabilities are likely to be well discussed. A thorough security analysis of all libraries a developer intends to use is a good best practice.

Code Obfuscation

Code obfuscation is done for several reasons in software development. In many cases, it happens to protect intellectual property in cases where a third party may try to rewrite the code and recreate a software program. Developers will use an encryption tool so that the code becomes unreadable. In simpler cases, the team may simply replace any metadata that contains sensitive information and replace variable names with random ones while maintaining the functionality of the code.

One of the most popularized incidents of data breach happened in 2016 whereby the personal details of 600,000 Uber drivers were exposed. This happened after developers uploaded code on GitHub containing credentials to access cloud hosting accounts on AWS.  This goes to show the importance of obfuscation and why overlooking it could result in massive reputational damage even for a large company.

Creators of malware also tend to use obfuscation to make their programs hard to decrypt.

Regular Updates

Frequent app updates are important to secure an app from evolving security threats. Developers have a role to remain in touch with developments in-app security and how best to keep out threats. One of the best ways to ensure users keep updating their apps is to send push notifications to prompt. Adding new features regularly also makes users excited about downloading updated versions of an app. The best practice is to ensure that the app is using all the latest and most secure versions of its dependencies.

Constant monitoring and logging of activity on the server side helps to detect incidents or anomalies in user activity. App developers must respond promptly to such threats.

Understanding Android App Security-Related Laws

Any development team in 2024 must strive to understand the data protection and user privacy laws in their jurisdictions. The EU’s GDPR set a high bar for compliance which many other countries follow. So far, both Meta and TikTok have received hundreds of millions of dollars of fines for various contraventions of privacy laws in Ireland where GDPR is applicable. Serious offenses can result in penalties of up to 20 million euros or 4% of company revenue, whichever is higher.

Fortunately, there are concerted efforts, especially by cloud service providers to help development teams and businesses comply with these laws.

Still, businesses are expected to have a clear privacy policy available for users. A privacy policy will normally explain how businesses use the data they collect from users and how well they handle it.

Diligent Error Handling

Improper messaging in case of an error, while an app is in use, can lead to inadvertent disclosure of sensitive system information. Such information can be used for malicious intent. Messages shown to users should be written with this in mind. It is also a best practice to log all errors for further analysis and resolution.  In fact, for major applications, there should be a dedicated team to ensure all incidents are well analyzed. It is not enough to fix the error. The team has to assess the impact of every incident.

Proper Session Handling

Poor session handling can lead to potential session hijacks on applications. This is why banking apps or payment wallets require users to sign in again after a brief period of inactivity. Developers should use session timeout effectively on their apps. Having to sign in many times can be disruptive for users but it is imperative for any apps that carry valuable user information that is an easy target for hackers.

Secure Data Backup

Most apps today are hosted on the cloud, thus limiting the size of apps on devices. This is a great practice because it makes storage cheaper and safer. Developers should choose the correct data-redundancy option depending on the value of their data. In the case of an attack or other unforeseen events, the organization can always recover data. In situations where data synchronization between app and cloud data does not happen in real time, backups should be scheduled to happen as often as reasonably possible.

Secure Development Training

Continuous training is necessary for developers to build safe Android apps. Software development teams need access to learning materials covering emerging app security trends.  There is a need to focus on app security testing, debugging, and even disaster management. Team members should appreciate the true cost of data breaches to an organization and to end users when personal information is in the wrong hands.

A data breach at Marriott International Inc. in 2018 was estimated to have cost the company over $200 million. Over 500 million hotel guests had their personal information exposed. The model used to estimate the cost considered costs of notifying the guests, credit monitoring, replacement of cards, forensic work, and credit monitoring.  Credit monitoring involves looking out for evidence of fraudulent credit activity following a breach. The model used in Marriot’s case did not take into account potential fines for contravening GDPR and other privacy laws.

Training should happen regularly in software development teams because of the speed with which new threats keep emerging. Fortunately, a lot of training resources are available for self-paced learning.

Choosing an Android App Development Partner

As seen, there are numerous best practices developers must adhere to when building Android applications. These recommendations have emerged over time as technology evolves and attackers find new ways to target applications.

The use of cloud storage today, for instance, is preferred over local data storage because the latter is an easier target for attacks. Installing external devices to expand device storage capacity and copying app data there creates clear security concerns. The external storage device can be easily lost or stolen and accessed by a third party. As such, app data today should ideally never be stored on an external storage device such as a memory card.

Man-in-the-middle attacks exploit vulnerabilities in the transport layer of most apps. Proper encryption of information through the choice of correct network protocols is vital for data protection. Rigorous penetration testing and other forms of testing are quite important for ease of mind regarding an app’s security robustness.

By working with the right app development partner, you can build and implement a proper security strategy for your Android application. App security ought to start during the design phase and should not come as an afterthought. Our team understands this and implements best practices such as user input validation and sanitization throughout the app. The choice of libraries, APIs, and all app dependencies is well thought out before the code is written.

With tens of years of experience in our team, we have witnessed the evolution of Android application security threats. Through it all, we have successfully delivered multiple secure applications to clients in the most data-sensitive fields. We would love to hear from you too. Reach out to us for partnership on your next mobile application project.

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