CVE-2024-0024 - UserManagerService.java Input Validation Vulnerability: Exploiting User Restrictions for Local Privilege Escalation

CVE-2024-0024 is a newly discovered vulnerability that affects Android devices. This vulnerability exists in multiple methods within the UserManagerService.java file, potentially leading to a local escalation of privilege (EoP), as user restrictions could be bypassed or not enforced. Although additional execution privileges are not required, user interaction is necessary for successful exploitation. In this post, we'll delve into the details of this vulnerability, discuss code snippets, and provide links to relevant resources.

Exploit Details

For a threat actor to exploit this vulnerability, they must first convince the user to install an Android application containing malicious code. This could be via social engineering tactics, such as disguising the application as a legitimate and useful tool. Once the user has installed and interacted with the application, the attacker can take advantage of the flawed input validation in UserManagerService.java to bypass or remove user restrictions, escalating their local privileges on the user's device.

Code Snippet

Below is an example of how an attacker could exploit the vulnerability via improper input validation in a UserManagerService.java method:

public class UserManagerService extends IUserManager.Stub {
    // ...
    public void setUserRestriction(String key, boolean value, int userId) {
        // ...
        if (!validateRestrictionsInput(key, value)) {
            // Log warning - Input validation failed
            Slog.w(LOG_TAG, "Failed to apply user restriction " + key);
            return;
        }
        // ... (Code proceeds to enforce user restrictions)
    }

    private boolean validateRestrictionsInput(String key, boolean value) {
        // ... (Code attempts to validate input)
        // Return false if input is deemed invalid or malicious
        return false;
    }
    // ...
}

In the example above, the setUserRestriction() method is responsible for enforcing user restrictions on the Android device. This method relies on the validateRestrictionsInput() method to verify that the provided input values are valid and secure.

However, due to the improper input validation, an attacker could potentially bypass this security measure by supplying a malicious input, which would allow them to escalate their local privileges on the user's device.

Android Open Source Project (AOSP) - UserServiceManager.java file

https://android.googlesource.com/platform/frameworks/base/+/master/services/core/java/com/android/server/pm/UserServiceManager.java

Android Security Bulletin for CVE-2024-0024

https://source.android.com/security/bulletin/2024-01-01

Mitigation

To protect your Android device from this vulnerability, ensure that you've installed the latest security updates from your device manufacturer or Android distributor.

Additionally, apply the principle of least privilege when granting permissions to third-party applications, and be cautious when installing applications from unofficial or unverified sources.

Conclusion

CVE-2024-0024 is a critical vulnerability in the UserManagerService.java file, which could lead to local privilege escalation on Android devices. By exploiting this flaw, an attacker could potentially remove or bypass user restrictions and gain unauthorized access to sensitive information or functionality. To minimize the risk of exploitation, always ensure that your device is up-to-date with the latest security patches and exercise caution when installing new applications.

Timeline

Published on: 05/07/2024 21:15:08 UTC
Last modified on: 07/09/2024 20:12:21 UTC