Repackaging

What is app repackaging?

Repackaging in mobile app security refers to the malicious practice of modifying legitimate mobile apps to include harmful elements like malware. Attackers redistribute these tampered apps on third-party platforms to deceive users into downloading them. Repackaging an app is a security threat and a serious concern for intellectual property theft.

Summary

When attackers repackage apps, they modify legitimate apps to include malware or unauthorized advertisements and then redistribute them through third-party platforms or unofficial app stores. Users download these legitimate-looking apps, unaware that they’re actually downloading malware. This compromises user data and undermines the functionality and integrity of the original app. Repackaged apps can lead to security breaches, exploiting users' trust in the original, legitimate apps.

Repackaging involves decompiling an app to access and modify its source code and then recompiling it back into an installable file. Android apps are particularly susceptible to repackaging due to the relative ease of manipulating APK files. Whereas, iOS apps are more secure due to Apple's stringent review processes, though jailbroken devices remain vulnerable.

Repackaged apps in the streaming industry, for example, can bypass subscription models and inject adware, causing revenue loss and exposing users to malware. Developers can mitigate these risks through code obfuscation, using digital signatures for integrity checks, adhering to secure coding practices for mobile security, educating users about the risks of unofficial downloads, and employing app shielding tools to detect and respond to tampering attempts in real time.

Deep dive

How are apps repackaged?

The process typically involves decompiling an app to access its source code, inserting malicious code or modifying existing functionalities, and then recompiling it back into an APK (for Android) or IPA (for iOS) file. These tampered apps are then distributed through third-party app stores, direct downloads, or phishing links, often masquerading as legitimate updates or cheaper/free versions of popular apps.

Repackaging iOS vs. Android apps

Android: Android devices are more susceptible to app repackaging because of the relative ease of decompiling and recompiling Android applications, Android's open ecosystem and the ability to install apps from third-party sources.
iOS: While iOS apps can also be repackaged, the process is more challenging due to Apple's stringent app review process and the closed nature of its ecosystem. iOS devices, by default, do not allow installations from outside the App Store unless they are jailbroken.

IP theft

Repackaging is a direct form of intellectual property theft. Developers' original code and digital assets are used without permission, often leading to brand damage and loss of revenue.

Ways to prevent repackaging

Code obfuscation: Implementing code obfuscation makes it harder for attackers to understand and modify the decompiled code.
Using app shielding tools: App shielding tools can provide runtime protection, detecting and responding to tampering attempts in real-time.
Digital signatures and integrity checks: Using digital signatures and routinely checking the integrity of the app can help verify that the app has not been tampered with since its release.
Secure coding practices: Following secure coding practices can minimize vulnerabilities that might be exploited during the repackaging process.
Educating users: Educating users about the risks of downloading apps from unofficial sources and encouraging downloads from trusted sources like official app stores.

Examples

Unauthorized streaming apps: Malicious actors repackage popular streaming apps to bypass subscription models, inject adware, or redirect payments to fraudulent accounts. This causes revenue loss and exposes users to malware and data breaches.
Fake gaming apps: Attackers repackage popular mobile games, adding cheat functionalities that appeal to players. These repackaged apps also contain malware designed to steal user credentials and in-app purchases.
Modified social media apps: Repackaged versions of social media apps often include additional features like the ability to download videos directly, which official apps do not allow. These modifications come with hidden spyware that can access and transmit personal data.
Ad-heavy utility apps: Utility apps are commonly repackaged with aggressive adware that generates revenue for cybercriminals. These ads not only degrade the user experience but can also lead to phishing sites.
Counterfeit productivity apps: Repackaged productivity apps may promise enhanced features, such as unlocked premium content for free. Users unknowingly expose themselves to ransomware.
Trojanized health apps: Health and fitness apps with added features like diet trackers or workout plans are often repackaged with malicious software called Trojans. These Trojans may collect sensitive health data or financial information.

History

Repackaging as a cybersecurity threat originated with the rise of mobile app ecosystems, particularly as Android and iOS platforms gained popularity in the late 2000s. Initially, repackaging was less about malicious intent and more about modifying apps to add features or remove restrictions, similar to jailbreaking. As mobile apps became integral to personal and financial activities, repackaging quickly evolved into a threat.

The ease of modifying Android apps due to their open-source nature and the APK file format led to a surge in repackaged apps containing malware, adware, or spyware being distributed through third-party app stores or deceptive links. On iOS, while more secure, jailbroken devices also faced risks from repackaged apps bypassing Apple’s strict App Store review process.

Future

Recent developments in the landscape of mobile app repackaging reflect a mix of emerging technologies, heightened threats, and evolving regulations. The increasing integration of Internet of Things (IoT) devices with mobile platforms introduces new vulnerabilities, as attackers find ways to repurpose IoT functionality for malicious mobile app modifications. Additionally, machine learning and AI technologies allow for more sophisticated detection of repackaging activities, but conversely, they also equip attackers with tools to create more advanced malware that can evade traditional security measures.

On the regulatory front, governments worldwide are tightening data protection laws, such as the EU’s General Data Protection Regulation (GDPR) and California's Consumer Privacy Act (CCPA), which impose stricter requirements on app developers to secure their applications and manage user data responsibly. These regulations push for better security practices and impact how developers and app stores monitor and manage third-party app integrations.

The latest change regulation comes in the form of the European Union’s Digital Markets Act (DMA). To reflect the DMA’s changes, users in the European Union can now install apps from alternative app marketplaces in iOS 17.4 or later. Users in the European Union can also install apps from a developer's website in iOS 17.5 or later. The country or region of your Apple ID must be set to one of the countries or regions of the European Union, and you must physically be located in the European Union.