Security vulnerabilities can hide in plain sight, often brought on by simple logic errors in code. CVE-2024-49720 is a recent example that affects Android devices. Specifically, it involves the Permissions.java file found at the heart of Android’s permission management. This long-read post will break down how this vulnerability can be exploited, walk through the relevant code, and help you understand why this flaw lets attackers bypass critical location permission checks—even without user interaction.

Explaining CVE-2024-49720

Vulnerability Summary:
In multiple functions inside the Permissions.java file in Android, a logic error allows a local attacker to override a user’s location permission state. This lets any local app escalate its privileges and access location information—without requiring more permissions or even user interaction.

How Does the Flaw Work?

The vulnerability comes from a flawed permission validation in Permissions.java, the file responsible for granting or denying sensitive access like location. The broken logic does not properly distinguish between changes made by the user and changes triggered by code—meaning an app can trick the system into thinking the user has given location access when they actually haven't.

Here is an illustrative example of what a vulnerable code section might look like

// Permissions.java (simplified and excerpted for clarity)

// This function is supposed to check if a given permission can be set
public boolean canSetPermission(String permission, boolean newState) {
    // Vulnerable logic: only checks the current state, not the source of the change
    if (permission.equals("android.permission.ACCESS_FINE_LOCATION")) {
        // Fails to check if change is user-triggered
        boolean oldState = getCurrentPermissionState(permission);
        if (!oldState && newState) {
            // Assumes any attempt to enable is allowed
            return true;
        }
    }
    return false;
}

The Mistake:
The code fails to differentiate whether the switch to newState happened through the settings UI (user action) or programmatically (from an app). As a result, a local app can elevate its own privileges just by flipping this state.

Exploit Walkthrough

Let’s see how an attacker could use this to their advantage.

Bypass User Interaction:

Instead of waiting for the user to grant permission through a dialog, the malware programmatically toggles the location permission flag.

Override User-Set State:

Due to the bug, the system thinks the user approved location access, so permission is granted and the app gets full location data.

Here’s a basic pseudo-code for what an exploit might call

// Exploit code running within a local app context.

// The app programmatically sets the location permission.
public void exploitLocationPermission() {
    // Reflection or service call to reach Permissions.java logic
    // WARNING: For demonstration only, do not use in production!
    setPermission("android.permission.ACCESS_FINE_LOCATION", true);
    
    // Now, the app can call location APIs without user having actually approved
    LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    Location loc = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    Log.d("Exploit", "Current location: " + loc.toString());
}

*Note: The real exploit may require reflection, specific intents, or IPC, depending on OEM customizations and Android version.*

References and Further Reading

- Official Android Security Bulletin
- CVE-2024-49720 at NVD

What Makes This Serious?

- No Extra Privileges Needed: Any local app can trigger this; it does not require root or special permissions.

Avoid installing apps from unknown sources.

- App developers: Review your permission logic and never assume internal state changes are triggered by the user.

Conclusion

CVE-2024-49720 is a stark reminder that even simple logic errors can have serious consequences—allowing privilege escalation and privacy invasion without the user ever knowing. Always keep your systems up to date, and remember: code audits and peer reviews are critical for securing permission-handling logic.

Timeline

Published on: 09/02/2025 23:15:32 UTC
Last modified on: 09/04/2025 17:47:36 UTC