CVE-2023-21081 - Bypassing Background Activity Launch Restrictions in Android PackageInstallerService and Associated Files

The Android operating system has evolved significantly since its inception to provide a robust and secure experience for users. However, software vulnerabilities may still arise, posing risks to local and remote devices. One such vulnerability found in multiple functions of PackageInstallerService.java and related files could potentially bypass background activity launch restrictions, allowing local escalation of privilege. This blog post will explore the details of this vulnerability, CVE-2023-21081, including a code snippet and references to the original sources of information. The exploit does not require additional execution privileges, and user interaction is unnecessary for its exploitation. The affected Android versions are Android 11, Android 12, Android 12L, and Android 13, identified as Android ID: A-230492955.

Exploit Details

In the PackageInstallerService.java file and related files that handle package installation and management, a logic error occurs within multiple functions, which provides the opportunity for malicious applications to bypass background activity launch restrictions. As a result, an attacker could exploit this vulnerability to perform local escalation of privilege, potentially gaining unauthorized access to sensitive data, resources or functionality, without the need for user interaction.

Code Snippet

The vulnerability exists in the following methods of PackageInstallerService.java and related files:

public class PackageInstallerService extends IPackageInstaller.Stub {
   ...
   private void foo() {
      ...
      if (isBackgroundLaunchRestricted) {
         // Background launch is restricted, but the logic error here
         // allows circumventing this restriction and triggering the
         // escalation of privilege.
         performRestrictedBackgroundLaunch();
      }
      ...
   }
   ...
}

The above snippet demonstrates a simplified view of the logic error within the PackageInstallerService class in the Android framework. The logic error in this code can be taken advantage of by crafting specific applications that utilize the bypass, allowing attackers to execute commands and overly intrusive tasks under escalated privileges.

Original References

This vulnerability was initially discovered by a security researcher and reported to the Android Security Program. The Android team acknowledged the issue and has assigned CVE-2023-21081 to this vulnerability. You can find more information about the issue at the following official links:

1. Android Security Bulletin - April 2023
2. CVE-2023-21081 - Android Security

Mitigation

The Android development team has released patches that address the issue in the affected versions. Device manufacturers will likely provide updates containing the appropriate patch to their users. It is highly recommended that users keep their devices up to date with the latest security patches to protect against such vulnerabilities.

Conclusion

Keeping the Android ecosystem secure is a top priority for the development team. While this CVE-2023-21081 vulnerability exposes risks to the users of the affected Android versions, it serves as a reminder of the importance of having an up-to-date device and using safe practices to protect against malicious applications. Always ensure to download apps from trusted sources, like the Google Play Store, maintain a strong defense system in the form of an antivirus, and stay informed about the latest security updates and vulnerabilities.

Timeline

Published on: 04/19/2023 20:15:00 UTC
Last modified on: 04/27/2023 20:45:00 UTC