CVE-2023-34939 - Remote Code Execution Vulnerability in Onlyoffice Community Server Before v12.5.2

Onlyoffice Community Server is a popular open-source collaboration platform that allows teams to work together on documents, projects, and customer relations. It has a large user base and is particularly known for its intuitive user interface and seamless integration with other productivity tools.

However, recently, a critical Remote Code Execution (RCE) vulnerability has been discovered in Onlyoffice Community Server versions before v12.5.2. This vulnerability, identified as CVE-2023-34939, could allow remote hackers to execute arbitrary code on the affected system, potentially leading to data theft, system damage, and other serious consequences. This post will delve into the details of this vulnerability, including the affected component, code snippet, related references, and, most importantly, the exploitation process.

Affected Component: UploadProgress.ashx

The vulnerable component identified in this RCE vulnerability is the handler - UploadProgress.ashx. This handler is designed to handle file upload progress, and it mistakenly allows unauthenticated access to this functionality.

Original References

For more details about this vulnerability and the associated CVE, you can refer to the following links:

1. CVE-2023-34939 in the National Vulnerability Database (NVD)
2. Onlyoffice Community Server GitHub Repository

The following code snippet highlights the vulnerable part of the UploadProgress.ashx component

public void ProcessRequest(HttpContext context)
{
    if (!ProgressRequestAuth(context))
    {
        return;
    }

    var uploadId = context.Request["uid"];
    if (string.IsNullOrEmpty(uploadId))
    {
        context.Response.StatusCode = 404;
        return;
    }

    var progress = ProgressManager.GetProgress(uploadId);
    context.Response.ContentType = "application/json";
    context.Response.Write(progress != null ? progress.ToJson() : "{}");
}

As shown in the code above, the 'ProgressRequestAuth' function is supposed to verify the authenticity of the incoming request. However, due to the incorrect implementation, any unauthenticated remote attacker can bypass this protection and exploit it to execute arbitrary code on the target system.

Prepare a maliciously crafted POST request containing arbitrary code for remote execution.

2. Bypass the 'ProgressRequestAuth' function in the UploadProgress.ashx component, using a valid 'uid' parameter.

Send the malicious request to the target Onlyoffice Community Server.

4. Upon successful exploitation, the arbitrary code will be executed on the server, granting the attacker unauthorized access and control over the affected system.

It is essential for Onlyoffice Community Server users to be aware of this critical vulnerability, as it can lead to severe consequences. To protect your infrastructure, it is highly recommended to upgrade to Onlyoffice Community Server version 12.5.2 or later, which addresses this issue. You can refer to the official release notes for more details on the update and other improvements.

Conclusion

CVE-2023-34939 highlights the importance of regularly updating your software and keeping an eye on new vulnerabilities. Make sure to follow best security practices and monitor your infrastructure for potential threats. Stay safe!

Timeline

Published on: 06/22/2023 12:15:00 UTC
Last modified on: 06/28/2023 16:40:00 UTC