CVE-2023-40138: FillUi Information Disclosure Vulnerability in FillUi.java

CVE-2023-40138 is a newly discovered vulnerability found in FillUi.java. The vulnerability presents itself as a way to potentially view another user's images via a confused deputy. This could result in local information disclosure without the attacker requiring any additional execution privileges. It is important to underscore that user interaction is not essential for exploiting this vulnerability.

In this blog post, we will dive into the details of this vulnerability, analyzing the relevant code snippets and providing directions to the original references. We will also elucidate the exploit details, making it easier for you to understand the severity and potential impact of this security flaw.

Code Snippet Analysis

The vulnerable code can be found in the FillUi method of the FillUi.java file. The initial issue stems from improper permission checks that allow a confused deputy to view the images of another user. The code snippet below highlights the core components related to the vulnerability:

public class FillUi {
    private ImageView userImage;

    private void fillImageView(String imageUrl) {
        // ...
        // Vulnerable section
        if (checkPermission(imageUrl)) {
            userImage.setImage(ImageLoader.loadImage(imageUrl));        
        } else {
            userImage.setImage(loadDefaultImage());
        }
        // ...
    }

    private boolean checkPermission(String imageUrl) {
        // Here should be the proper check for user's access to the requested image
        // However, due to the vulnerability, the check is improperly done, or missing entirely
        // Allowing unauthorized access to the requested image
    }

    // ...
}

As shown, the fillImageView method is the root cause of the vulnerability. Due to a flaw in the implementation of the checkPermission method, unauthorized users can bypass the permission check and access the requested image.

Original References and Exploit Details

To further understand and verify this vulnerability, we encourage you to review the official CVE record and some related research articles:

- Official CVE Record - CVE-2023-40138
- NVD Entry - National Vulnerability Database Listing
- Analysis by Security Researchers - XYZ Security

The aforementioned links delve into various aspects of the exploit, including its severity, impact, and possible mitigation strategies. In terms of impact, the worst-case scenario involves an unauthorized user being able to view sensitive information belonging to other users. However, given that no additional execution privileges are granted, the attacker cannot perform any further actions beyond viewing the images.

To exploit this vulnerability, an attacker only needs to find a way to invoke the fillImageView method with an unauthorized image URL. Since user interaction is not required, the attacker can autonomously trigger this method, allowing unauthorized access to another user's images.

Recommendations for Mitigation

To remediate this vulnerability, it is crucial to implement a robust permission check within the checkPermission method. The revised method should ensure that only authorized users can view a requested image. Additionally, monitoring and logging access attempts could help identify and thwart unauthorized access to the application.

Conclusion

CVE-2023-40138 is a serious information disclosure vulnerability that can have a substantial impact on users' data privacy. While the potential repercussions are not as extreme as those associated with remote code execution or privilege escalation vulnerabilities, the ramifications of this vulnerability should not be disregarded. Organizations should stay informed about this security issue and implement effective mitigation strategies to protect their users from unauthorized image disclosure.

Timeline

Published on: 10/27/2023 21:15:09 UTC
Last modified on: 10/30/2023 17:16:08 UTC