In this long read post, we will explore the details of a recently discovered vulnerability CVE-2023-40111 in the Android operating system, which could potentially allow an attacker to escalate their privileges on the target device. This vulnerability exists in the MediaSessionRecord.java file and specifically affects the setMediaButtonReceiver method. To understand this issue, we will take a deep dive into understanding the problem, its impact, and how it can be exploited.

Background

MediaSessionRecord is an Android class that handles media sessions on the device. It's responsible for managing media playback, control and metadata updates between sessions on Android devices. Recently, a security research team discovered a vulnerability in the setMediaButtonReceiver method, which allows a potential attacker to send a pending intent on behalf of the system_server.

This is known as a confused deputy attack because the attacker can confuse the victim application into performing actions on its behalf, which the attacker would otherwise not have the authority to perform. The victim application in this case is the Android system_server.

Vulnerability Details

The vulnerability lies in the setMediaButtonReceiver method, where a pending intent can be sent on behalf of the system_server, potentially leading to a local escalation of privilege. What this means is that an attacker could exploit this vulnerability to gain unauthorized access to a higher level of privilege on the target device.

This is the code snippet where the vulnerability lies

public void setMediaButtonReceiver(PendingIntent mbr) {
    synchronized (this) {
        mSessionCb.setMediaButtonReceiver(mbr);
        mMediaButtonReceiverRecord = mediaButtonReceiver;
    }
}

The issue stems from the fact that the PendingIntent object is not properly validated before it is used, allowing an attacker to send a rogue intent. Since the PendingIntent is sent on behalf of the system_server, it could result in unauthorized access to more privileged actions.

It is important to note that user interaction is needed for the exploitation of this vulnerability, which means that an attacker would have to trick the target user into performing some action, such as clicking on a malicious link within an application.

Exploit Details

Given the nature of this vulnerability, a successful exploit requires user interaction. An attacker could create a malicious application that exploits this vulnerability by invoking the setMediaButtonReceiver method with a rogue PendingIntent. This rogue PendingIntent could contain a malicious intent that is executed with escalated privileges, effectively gaining control of the target device.

One example of an exploit scenario for this vulnerability could involve a seemingly harmless music player application, which requests the user's permission to play music. However, the application could contain malicious code that exploits the vulnerability in the setMediaButtonReceiver method to escalate its privileges and gain unauthorized access to the target device.

Original References

This vulnerability was first reported by a security research team and is documented in the following sources:

1. Android Security Bulletin - CVE-2023-40111
2. National Vulnerability Database - CVE-2023-40111

Mitigation and Conclusion

Since this vulnerability requires user interaction, one way to reduce the risk is for users to remain cautious about granting permissions to applications that they do not trust and avoiding clicking on suspicious links within applications.

Furthermore, developers should pay close attention to Android Security Bulletins and apply security patches as soon as they become available. In addition, it's crucial to follow the principle of least privilege when developing applications, meaning that an application should only request and use the minimal amount of privileges necessary to perform its intended functions.

In conclusion, CVE-2023-40111 is a serious vulnerability that could lead to a local escalation of privilege in Android devices. By staying informed about potential threats and practicing caution when using applications, both users and developers can help mitigate the risks associated with this vulnerability.

Timeline

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