A recent cybersecurity vulnerability, identified as CVE-2023-4721, has been discovered in the GitHub repository gpac/gpac, which is a multimedia framework used for research and academic purposes, as well as multimedia services such as encoding, streaming, and decoding. The vulnerability in question is classified as an out-of-bounds read, meaning that an attacker can potentially access memory locations outside the intended boundaries. Fortunately, this issue only affects versions of gpac prior to the 2.3-DEV release.

In this post, we will take an in-depth look at the CVE-2023-4721 vulnerability, discussing the details of the exploit and how to address it through code snippets and original references.

Exploit Details

The vulnerability lies in the processing of specific multimedia files. When gpac parses certain files, the program may read memory locations that are out of bounds. This out-of-bounds read can potentially lead to information leaks or even application crashes.

For example, consider the following code snippet that demonstrates the out-of-bounds read.

void process_data(char* data, int length){
    int index = ;
    while(index < length){
        char value = data[index + 1]; // Potential out-of-bounds read
        // Process data
        index++;
    }
}

The above code snippet processes the provided input data of size length. When trying to access the next character in the data array with data[index + 1], there is a potential for an out-of-bounds read, as the code is not checking if the index variable is within the bounds of the array.

GitHub Issue: Out-of-bounds Read in gpac repository

Solution

A patch has been released to address this vulnerability in the gpac 2.3-DEV release. The patch fixes the out-of-bounds read issue by ensuring that the index is checked against the array boundaries. Here is a code snippet demonstrating the fix:

void process_data_fixed(char* data, int length){
    int index = ;
    while(index < length){
        if(index + 1 >= length){
            break; // Prevent out-of-bounds read by checking against array boundaries
        }
        char value = data[index + 1];
        // Process data
        index++;
    }
}

The fixed code snippet utilizes a check (if(index + 1 >= length)) that prevents the out-of-bounds read by comparing the index against the array boundaries.

Conclusion

CVE-2023-4721 is an important vulnerability for developers and users of the gpac multimedia framework to be aware of, particularly those using versions prior to 2.3-DEV. Upgrading to the newest version or applying the provided patches will help mitigate the risks associated with this out-of-bounds read.

Always stay on top of security updates and follow best practices in software development to minimize the likelihood of vulnerabilities that could compromise your applications' integrity.

Timeline

Published on: 09/01/2023 16:15:00 UTC
Last modified on: 09/06/2023 00:15:00 UTC