In the Android Open Source Project (AOSP), there exists a vulnerability in the UsbConfiguration.java file, specifically within the createFromParcel() method. This vulnerability, dubbed CVE-2023-40109, could potentially lead to background activity launch (BAL) in affected devices due to a permissions bypass. In order to exploit this vulnerability, no additional execution privileges are required, but user interaction is needed. In the rest of this long read, we will take a deep dive into the vulnerability, including code snippets, original references, and exploit details.

The Code and The Bug

The bug lies in the UsbConfiguration.java file, part of the Android framework, which deals with USB device configuration management. The code snippet below shows the createFromParcel() method:

public static final Parcelable.Creator<UsbConfiguration> CREATOR =
        new Parcelable.Creator<UsbConfiguration>() {
    public UsbConfiguration createFromParcel(Parcel in) {
        int id = in.readInt();
        String name = in.readString();
        int attributes = in.readInt();
        int maxPower = in.readInt();
        ArrayList<UsbInterface> interfaces = createInterfaces(in, in.readInt());
        String desc = in.readString();
        return new UsbConfiguration(id, name, attributes, maxPower, interfaces, desc);
    }

    public UsbConfiguration[] newArray(int size) {
        return new UsbConfiguration[size];
    }
};

The vulnerability is a permissions bypass, which allows for background activity launch (BAL) without proper permission checks. Due to this, an attacker could potentially exploit the vulnerability to elevate their privileges.

This vulnerability has been documented in the National Vulnerability Database (NVD) here. The entry provides further details, including the Common Vulnerability Scoring System (CVSS) score.

Additionally, the Android Open Source Project (AOSP) has acknowledged the vulnerability and mentioned it in their security bulletin here. The bulletin provides insight into the affected versions of Android and possible mitigations.

To exploit this vulnerability, an attacker would need to perform the following steps

1. Trick the user into performing certain actions on their device, such as downloading a malicious app or visiting a phishing website. As mentioned earlier, user interaction is necessary for exploitation.

2. The attacker can then bypass the permission checks, leading to background activity launch (BAL) without proper authorization.

3. Once the attacker gains access to background activities, they can potentially monitor user activities, steal sensitive information, or perform other malicious actions.

Mitigation and Prevention

Google has fixed this vulnerability in the latest security updates for Android. Users are advised to update their devices to the latest security patch available and regularly check for updates. In addition, users should exercise caution when downloading apps or visiting unfamiliar websites, as these could potentially be used to exploit this vulnerability.

Conclusion

CVE-2023-40109 is a serious vulnerability that could allow for local escalation of privilege due to a permissions bypass in the UsbConfiguration.java file of the Android framework. By understanding the details behind this vulnerability, including the affected code, the original references, and how an attacker could potentially exploit the vulnerability, we can take appropriate measures to protect our devices and ourselves from potential exploits. Always keep your Android device up to date and be cautious about the apps you install and the websites you visit to minimize the risk of falling victim to such vulnerabilities.

Timeline

Published on: 02/15/2024 23:15:08 UTC
Last modified on: 02/16/2024 13:37:55 UTC