We live in a world of apps. There’s a mobile app for almost everything, so it makes perfect
sense if you, too, want to develop an app for your business (or have developed it already).
However, 2020 has taught us that our responsibility as an app developer is not only to create an app,
we have to find the security risks, and mitigate them. Apps that compromised
user security and privacy were hit hard by their users and Google in 2020. So you should
ensure while coding your apps in 2021 that you follow some app security best practices
essential for the safety of your apps and user data.

Now you must be wondering, what are those best practices? Here we will tell you about 9
Android app security best practices that must be followed by every developer in 2021.
Let’s begin!

#1. Force usage of strong passwords

One of the most basic yet underrated things about app security is passwords. Developers
often do not pay enough attention to them, but all security begins with passwords. If you
allow your app’s users to use weak passwords for their accounts, their data may be stolen
easily by various attacks like guessing, brute-forcing, etc. Enforce the use of strong
passwords in your app by creating passwords that require a mix of alphabets, numbers, and
special characters. No one should be allowed to create an account on your app until they
make such a password. Some of your customers may hate you for it, but this is an essential
step for app security.

#2. Enforce secure coding standards.

Coding is an art, and secure coding is another level of skill. It takes a certain level of
knowledge, experience, and expertise to be aware of all secure coding best practices and
become habitual of incorporating them while coding an app. Therefore, in 2021 you should
try to enforce safe coding standards in all the apps you develop. That requires hardening of
code while considering various important parameters. Some of those parameters include:

• Unnecessary modules and servers
• Storage of session information
• Software’s access to filesystem
• Access to servers having sensitive information.
• Possibility of remote code execution
• Agility of code
• Maximum time consumed in script execution, etc.

These are a few of the various important parameters that must be considered while
developing an app to enforce secure coding standards.

#3. Sign your code

SSL certificates make mobile applications more trustworthy. Always sign your app’s code
with a code signing certificate (a type of SSL certificate) before compiling it. Code signing certificates helps users ensure that the app installer has indeed been developed by you
only and no one else has tampered with the installer file after you compiled it. Suppose
someone tampers with an application installer whose code has been signed. In that case,
the code signature becomes invalid, and the operating system prevents the installation of
such an app by warning the users who try to install it. So if someone tries to compromise
your applications installer file by injecting malicious code in it, they won’t be successful
because users will be alerted of it even before installing the app. You can buy code signing
certificates and install them on your computer to sign your app’s code.

#4. Use authorized APIs

APIs are tricky. While their purpose is to streamline app development and reduce
complications involved in accessing data and interact with external components if they’re not
appropriately coded, they can unintentionally allow hackers to crack into your app and steal
user data. Therefore, you should use only centrally authorized APIs in your apps for secure
mobile app development. You should also avoid caching of authorization data because
that provides another point to hackers who want to steal authorization information and break
into your app.

#5. Source Code Encryption (Obfuscation)

No discussion on cybersecurity can be complete unless we talk about encryption, which
applies to secure coding. Encryption scrambles the plain text information into unreadable
strings of text that won’t make sense to anyone until hashed with a private key. In coding,
the encryption of source code is known as obfuscation, and it achieves the same purpose
(making code unreadable), although in a slightly different manner. Instead of hashing the
code, obfuscation increases its unreadability by removing comments, renaming variables,
and removing whitespaces. Obfuscation tools also use many other techniques to make the
source code unreadable, and you should use such tools in 2021 to make your code tough to
break-through.

#6. Use third-party libraries carefully.

Third-party libraries are used heavily by most app developers to incorporate new
functionalities, integrate external services, and achieve a variety of other purposes. While
they’re handy, using them ties your code to the code of a third-party. This may lead to two
significant problems:

• If there’s a vulnerability in the code of the library, it also becomes a part of your app
• If you decide to change the library in the future, that means making significant
  changes in your app’s code and functionality.

That’s why you should be very careful while working with third-party libraries to code your app.

Always use well-developed and reputed libraries with a long history of reliability and a stable community around them.

Also, keep updating your libraries regularly and make use of internal repositories whenever possible to limit the risk for your app.

#7. Ensure proper session handling at all times.

Often, websites also get hacked because they fail to manage the session information of their
administrators or other users in a proper way. And it’s more critical to handle sessions
carefully on mobile devices than for desktops because, on mobile devices, sessions last
much longer than they stay on desktops. Here are some tips that you can follow to ensure
correct session handling on all types of devices:

• Always use tokens instead of device identifiers for the session ID. Tokens can be
  revoked (i.e., expired) at any point in time, something that’s not possible for device
  identifiers.
• Enable the functionality of remote log-off and remote data wipe for lost devices.
• Use lengthy strings for tokens that are hard to generate by any automated tools and
  don’t reveal any other meaningful information.

#8. Pay attention to data security

When you develop your app, you can choose between using internal storage or external
storage to store app data. This choice should be made carefully because data stored in the
phone’s internal storage is protected by a proper permission structure set up by Android,
unlike external storage, whose permission structure is an all-or-none affair. So if your app
requires local storage of sensitive user data, always use internal storage to store your app
data. If that’s not the case and your app doesn’t require storing sensitive user data locally,
you can use external storage for app data. You may also consider adding your layer of
encryption over the default encryption layer of Android for sensitive data stored in internal
storage.

#9. Automate your vulnerability management

Finding vulnerabilities and fixing them is not a one-off task that you can do when developing
your app and then forget about it. It requires constant auditing and bug fixing to create and
maintain a secure and challenging app to break-through. Therefore, instead of doing this
task yourself, we would advise you to automate your vulnerability management. There are
tools available in the market that can scan both iOS and Android apps for vulnerabilities and
fix the loopholes that they find automatically. Endpoint Detection and Response tools (EDR),
Network Access Control (NAC) tools, and firewalls can help you in this regard.

Conclusion

These were the nine critical best practices you must follow in 2021 for the security of your
apps. The last few years have taught us a lot about these steps’ importance as many
notable cyberattacks on mobile apps took place. Therefore, it’s essential to take these steps
seriously and implement them carefully while coding your app.

If you’ve any questions about any of these steps, share them in the comments. And if not, start coding your app with these
best practices.

All the best!