A new vulnerability in the popular Android ecosystem has been recently discovered that enables arbitrary app code execution as a privileged app. Identified as CVE-2024-23710, this vulnerability affects the "assertPackageWithSharedUserIdIsPrivileged" function within the "InstallPackageHelper.java" file. This could potentially lead to a local escalation of privilege without requiring any additional execution privileges or even user interaction for exploitation.

In this post, we will dive deep into this vulnerability, provide a detailed explanation along with code snippets, and links to original references and resources. Our aim is to help users, developers, and cybersecurity professionals better understand the implications of CVE-2024-23710 and develop appropriate mitigations to minimize the risk of exploitation.

The vulnerability: An overview

The "assertPackageWithSharedUserIdIsPrivileged" function in "InstallPackageHelper.java" could potentially suffer from a logic error in the code, which might allow a malicious app to run arbitrary code as a privileged app. The core of the problem lies within how the function handles shared UIDs, which are a feature in Android that allows multiple apps to share the same UID (user identifier) in order to facilitate resource sharing and communication.

The problem arises from the fact that the "assertPackageWithSharedUserIdIsPrivileged" function does not properly validate if an app with the shared UID is actually a privileged app, enabling any app with the shared UID to potentially execute code as a privileged app. This can lead to a malicious app effectively bypassing Android's security measures and gaining unauthorized access to sensitive information or resources on the device.

Code snippet illustrating the vulnerability

Here is a code snippet taken from the "InstallPackageHelper.java" file, which demonstrates the problematic logic:

private void assertPackageWithSharedUserIdIsPrivileged(PackageParser.Package pkg,
        int sharedUserId, int uid) throws PackageManagerException {
    final String sharedPackageName = mPackages.getPackageForUid(sharedUserId);
    if (sharedPackageName != null && isSharedUserPrivileged(sharedUserId, uid)) {
.newBuilder() mPackageManager.getPackageInfo(
        sharedPackageName,  /* flags */, userId);
                return;
            } catch (android.os.RemoteException e) {
                // Couldn't communicate with Package Manager service.
                throw new PackageManagerException("Error checking package "
                        + sharedPackageName + " [" + userId + "]");
            }
        }

        // At this point, none of the currentUser's packages with the sharedUserId
        // are privileged. Throw exception as an early fail in case code continues
        //with install and fails with an obtuse error message.
        throw new PackageManagerException("Attempt to install unprivileged "
                + "application as userId=" + userId + " in sharedUid="
                + pkg.applicationInfo.sharedUserId);
    }
}

As we can see from the code, the function first checks if the sharedPackageName is available and the shared user is indeed privileged. However, there is no proper validation that ensures the incoming app is actually privileged or not, leading to the aforementioned exploit.

For those interested in learning more about CVE-2024-23710 and its implications, here are some relevant resources and links:

1. CVE-2024-23710: Android Security Bulletin – This link provides detailed information on the vulnerability, its impacts, and potential mitigations.
2. Android Package Manager Overview - A comprehensive documentation of the Android Package Manager, its functionalities, and how it interacts with the system.

Exploit details

As mentioned earlier, CVE-2024-23710 enables an attacker to execute arbitrary code as a privileged app without user interaction, making it an attractive target for potential exploitation. By leveraging this vulnerability, a malicious app could gain unauthorized access to sensitive system data, device configurations, or user information. Furthermore, an attacker could even bypass Android's built-in security measures such as permissions, considerably compromising the security and privacy of a user's device.

In conclusion, CVE-2024-23710 poses a significant risk to Android users and developers. By understanding the nature of this vulnerability and its potential implications, it is essential for users, developers, and cybersecurity professionals to be proactive in identifying and mitigating this risk. This can help ensure the continued safety and security of the Android ecosystem and protect against potential exploitation.

Timeline

Published on: 05/07/2024 21:15:08 UTC
Last modified on: 07/03/2024 01:48:04 UTC