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App shielding

How to think like a hacker to secure your Android app

By Benjamin Adolphi September 11, 2023 01:01 pm

Ever wonder how secure your app really is? Dive into this blog post to learn why thinking like a hacker can be your secret weapon against app attacks. We’re talking reverse engineering, repackaging, hooking, and more. Plus, get actionable takeaways to level up your app’s security game.

Why thinking like a hacker matters

If you’re an Android developer, you’ve probably spent countless hours perfecting your app’s user interface, optimizing performance, and debugging code. But have you thought about how secure your app is? Understanding the mindset of a hacker can be your first line of defense against various types of attacks that can compromise your app. In this blog post, we’ll dive into key areas like reverse engineering, repackaging, hooking, and debugging to help you fortify your Android app.

The basics of reverse engineering

Reverse engineering is the process of breaking down something to understand how it works, either to replicate it or to enhance it. In the context of Android apps, this means understanding the app’s architecture and code. Attackers often start by reverse engineering an app to find vulnerabilities. They use tools to decompile the app and examine its APK file. This can reveal sensitive information like passwords or encryption keys.

💡 Takeaway: Make reverse engineering harder

To protect against reverse engineering, consider obfuscating your code. Different tools can rename classes, fields, and methods with meaningless names, making it more difficult for someone to understand the code’s functionality. You should also encrypt sensitive strings and assets in your app. This adds an extra layer of security that can deter attackers.

The threat of repackaging

Repackaging is a subtle but serious threat. In this type of attack, hackers modify an existing app to change its behavior. They disassemble the app, modify the code, and then repackage it into a new APK file. This modified app can then be redistributed, posing a significant security risk.

💡 Takeaway: Implement safeguards against repackaging

To counter repackaging attacks, implement APK signature verification to ensure that the app being run is the one you published. You can also use checksumming to verify the integrity of your app’s files. These measures can alert you if your app has been tampered with, allowing you to take corrective action.

Learn more about repackaging in our App Threat Report: The State of Repackaging, where we tested hundreds of financial services apps across various sectors and regions to assess the overall level of security against this common attack.

Get the repackaging report

Hooking: real-time app modification

Hooking allows attackers to modify an app while it’s running. This is done by inserting code, usually at the beginning of the target code, which jumps to another location in memory where the attacker’s code is executed. This can be used to log or manipulate arguments and can change the app’s behavior in real-time.

💡 Takeaway: Fortify your app against hooking

To make hooking more difficult for attackers, use multiple independent security mechanisms at different levels. For example, you can implement runtime checks to detect if hooking frameworks like Xposed or Frida are active. Also, consider using native code for sensitive operations, as it’s generally harder to hook than Java code.

Gaming apps can be a common target for hooking attacks. In a recent report, we tested more than 350 of the top Android games by revenue, exploring how they protect themselves against hooking frameworks, repackaging, and rooted devices.

Download the app threat report

Debugging: a tool and a threat

Debugging is often considered a tool for developers, but it can also be a weapon for attackers. By enabling debugging in an app, attackers can understand and even modify its behavior. This can be done both for Java code and native code, making it a versatile method for compromising app security.

💡 Takeaway: Minimize debugging risks

To protect against unauthorized debugging, disable debugging in your app’s production version. Android provides an API, Debug.isDebuggerConnected(), that can be used to detect if a debugger is connected. Use this API along with other monitoring techniques to alert you of any unauthorized debugging attempts.

Countermeasures to consider

While no security measure is foolproof, implementing multiple layers of security can make your app more resilient against attacks. This includes code obfuscation, monitoring for signs of debugging or hooking, and implementing APK signature verification.

💡 Takeaway: Layer your security measures

When it comes to app security, the best defense is always a multi-layered approach. Use a combination of code obfuscation, encrypted strings, runtime checks, and APK verification to make your app as secure as possible. Remember, each layer of security you add makes it that much harder for an attacker to compromise your app.

Wrapping it up

Understanding the vulnerabilities in your Android app is the first step to securing it. By thinking like a hacker, you can anticipate potential threats and implement countermeasures to protect your app and its users.

Want to dive deeper into Android app security?

Don’t miss out on our comprehensive webinar that covers everything you need to know. Access the on-demand webinar now to deepen your understanding and take your app’s security to the next level.

Benjamin Adolphi, Head of Security Research at Promon, will be your guide. He has spent over a decade investigating mobile application threats and defenses, and is ready to share his insights with you.

Check out the webinar
How to hack (and secure) an Android app!