The flvmeta v1.2.2, a popular metadata parser for FLV files, has a recently discovered vulnerability that allows a local attacker to potentially execute a denial of service (DoS) attack using a specially crafted FLV file. This vulnerability, designated as CVE-2024-25385, involves the flv_close function found in flvmeta/src/flv.c:375:21. In this post, we will examine this issue, discuss potential challenges that an attacker might exploit, and provide some insights into what can be done to mitigate these risks.

Description of the Issue

The CVE-2024-25385 vulnerability exists in the flvmeta v1.2.2 software due to an improper handling of certain FLV files. If an attacker can craft a malformed FLV file and process it using the affected flvmeta software, it may cause a denial of service condition by triggering the flv_close function inappropriately. The affected function can be found here:

flv.c:375:21 Source Code on Github

The key code snippet from flv.c that demonstrates the vulnerability

FLVEXPORT void
flv_close(FLVContext *flv) {
    if (flv && !flv->invalid)
    {
        if (flv->strict || flv->normal)
            fflush(flv->file);
        fclose(flv->file);
        flv->file = NULL;
        flv->invalid = 1;
    }
}

Details of the Vulnerability

The vulnerability arises due to the improper handling of certain FLV files by flvmeta. In a normal scenario, the flv_close function would be called after the stream has been properly processed and would close the file and mark it as invalid. However, a specially crafted malformed FLV file could cause the flv_close function to be called prematurely, leading to a potential denial of service attack.

For an attacker to successfully exploit this vulnerability, they would need to have crafted an FLV file with the necessary structures and values that trigger the flv_close function to execute at an unintended point. Additionally, the attacker would need to have access to the system where the targeted flvmeta software is running, or the system would need to process the crafted FLV file automatically.

Mitigation and Recommendations

To address the CVE-2024-25385 vulnerability, it is essential for developers and system administrators to take appropriate precautions. These can include:

1. Upgrading to the latest version of flvmeta: To protect against this vulnerability, developers should upgrade to the latest version of flvmeta software. If a patch is released that addresses this issue, apply it as soon as possible.

2. Proper Input Validation: Always follow best practices when handling user-supplied input, such as data validation and sanitization wherever possible, to prevent potential exploits involving crafted FLV files.

3. Monitor and Audit Software: Perform regular security assessments of your applications and infrastructure to identify potential vulnerabilities and apply relevant mitigations to reduce their impact.

Conclusion

CVE-2024-25385 is a dangerous vulnerability in flvmeta v1.2.2 that allows an attacker to potentially execute a denial of service attack using a crafted FLV file. By understanding the details of this vulnerability and employing proper input validation, monitoring, and auditing practices, developers and system administrators can reduce the impact of this vulnerability on their applications and systems.

For more information on CVE-2024-25385, follow the original references and advisories

- CVE-2024-25385 - National Vulnerability Database
- flvmeta v1.2.2 Source Code and Releases

Timeline

Published on: 02/22/2024 19:15:09 UTC
Last modified on: 02/23/2024 02:42:54 UTC