CVE-2024-49724 - Race Condition in AccountManagerService.java Enables Privilege Escalation on Android

In early 2024, a new security vulnerability—CVE-2024-49724—was uncovered in Android's AccountManagerService.java. This flaw allows a local attacker to bypass security permissions via a race condition, letting them launch protected activities they're not supposed to access. No special execution privileges are needed. However, user interaction is required for successful exploitation.

Let’s break down what this means, see how it works, and explore how it can be exploited with exclusive details and easy-to-understand explanations.

What Is AccountManagerService?

AccountManagerService is a core Android service responsible for managing accounts—think of your Google, Twitter, or Facebook logins on your device. It oversees the permissions and restrictions for those accounts and activities associated with them.

The Vulnerability: Race Condition for Permission Bypass

In several functions within AccountManagerService.java, there is a Race Condition—meaning two or more operations happen at the same time, and this can be exploited to break the intended security. Specifically, a malicious app could, with the right timing, bypass the usual permission checks and launch a protected activity.

Here’s what happens

- Usually, when an app tries to launch a protected activity, Android checks if it has the right permissions.
- Due to a small timing window, an attacker can trigger a state where these checks are temporarily bypassed if they act quickly enough—giving them access they shouldn’t have.

A Simplified Code Example

Below is a simplified version illustrating the race condition in AccountManagerService.java (for clarity; actual source is more complex):

// This is an illustrative snippet
public void startActivityWithPermissionCheck(UserHandle user, Intent intent) {
    if (!hasPermission(user)) {
        throw new SecurityException("No permission!");
    }
    // Race condition opportunity here:
    // If 'hasPermission' result changes here
    context.startActivityAsUser(intent, user);
}

An attacker could, in theory, manipulate the user state between hasPermission() and startActivityAsUser, slipping through the checks by exploiting this tiny timing window.

1. Malicious App Preparation

An attacker creates an app that times requests just right to hit the window above between the permission check and actual launch of the activity.

2. User Triggers App

User must interact with the malicious app (e.g., clicking a button or accepting a dialog), which kicks off the rapidly-timed request.

3. Race Condition Hits

If the attacker’s request lands precisely during that vulnerable window—right after the permission check, but before launching the activity—the system spawns the protected activity without proper authorization.

4. Escalation

Attacker gains access to protected system activities (e.g., account settings, other users’ credentials), potentially leading to:

Other privilege escalation scenarios

No special device permissions or root access are necessary—just clever timing and user interaction.

References and Technical Details

- CVE Record: NVD - CVE-2024-49724
- Android Open Source Code: AccountManagerService.java (AOSP)
- Initial Advisory: Android Security Bulletin - June 2024
- Related Documentation: AccountManager | Android Developers

Example Exploit Workflow (Pseudocode)

// Attacker's app, highly simplified
Button exploitButton = findViewById(R.id.exploit_button);
exploitButton.setOnClickListener(v -> {
    for(int i = ; i < 100; i++) {
        new Thread(() -> {
            // Tries to launch protected activity rapidly in hopes of hitting the race window
            launchProtectedAccountActivity();
        }).start();
    }
});

*In practice, the attacker would also monitor system state changes and possibly try to temporarily influence permissions during this rapid-fire period.*

Update System: Ensure you have the June 2024 Android security patch for your device.

- Check App Permissions: Be wary of any apps asking for account or system settings access. If you don’t recognize the app, don’t grant permissions.
- User Review: Always scrutinize apps before granting them sensitive access or responding to suspicious prompts.

Conclusion

CVE-2024-49724 is a classic example of how even well-protected systems like Android can be vulnerable to subtle, split-second mistakes. While this vulnerability does require some user interaction, the escalating privileges risk is very real.

For a deep dive, check the sources above, follow the Android Security Bulletins, and always use an up-to-date device. If you're a developer, review your code for similar timing and state-check issues—race conditions happen more often than you think.


*Stay safe, and keep your systems updated! For more technical info, visit the official CVE entry.*

Timeline

Published on: 01/21/2025 23:15:14 UTC
Last modified on: 01/22/2025 18:15:19 UTC