CVE-2023-24998: Apache Commons FileUpload Denial of Service Vulnerability

Background

Apache Commons FileUpload is a popular Java library that provides a simple and flexible API for uploading files to a server. It is commonly used in web applications to handle file uploads. The library allows developers to parse and process multipart/form-data requests, making it easier to handle file uploads in a standardized way. However, versions prior to 1.5 of Apache Commons FileUpload are vulnerable to a denial of service (DoS) attack.

Vulnerability Detail

The vulnerability in Apache Commons FileUpload before version 1.5 arises from the lack of limitation on the number of request parts that can be processed. This allows an attacker to exploit the library by sending a large number of malicious upload requests or a series of uploads, overwhelming the server's resources and causing a DoS condition. It is important to note that the new configuration option to limit the number of request parts (FileUploadBase#setFileCountMax) is not enabled by default and must be explicitly configured.

Workaround

If upgrading to Apache Commons FileUpload 1.5 is not immediately feasible, a temporary workaround is to manually limit the number of request parts processed in the application code. This can be achieved by implementing custom logic to count the number of request parts and rejecting requests that exceed a certain threshold. Here's an example of how this can be done in Java:

import org.apache.commons.fileupload.FileUploadBase;

public class CustomFileUpload extends FileUploadBase {

  @Override
  protected void parseRequest() throws Exception {
    // Add custom logic to count request parts
    int requestPartCount = 0;
    for (FileItemIterator iter = getItemIterator(request); iter.hasNext(); ) {
      // Process request parts
      requestPartCount++;
      // Check if the request part count exceeds the threshold
      if (requestPartCount > MAX_REQUEST_PARTS) {
        throw new FileUploadException("Too many request parts");
      }
    }
  }

}

Conclusion

In conclusion, Apache Commons FileUpload versions prior to 1.5 are vulnerable to a denial of service (DoS) attack. To mitigate this vulnerability, it is recommended to upgrade to Apache Commons FileUpload 1.5 or later. Alternatively, developers can implement custom logic to limit the number of request parts processed in the application code. For further support on vulnerability remediation, please contact DevNack.com.

See every vulnerability recorded for commons-fileupload:commons-fileupload →

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