CVE-2014-0481: Django Sequential File Name Generation Denial of Service

Background

Django is a popular Python web framework that provides a set of tools and libraries for building web applications. It includes a file upload handling system that allows users to upload files to the server. However, prior to versions 1.4.14, 1.5.x before 1.5.9, 1.6.x before 1.6.6, and 1.7 before release candidate 3, Django's default configuration for file upload handling used a sequential file name generation process. This means that when a file with a conflicting name is uploaded, Django appends a number to the file name to make it unique. This vulnerability allows remote attackers to cause a denial of service (CPU consumption) by uploading multiple files with the same name.

Vulnerability Detail

The vulnerability arises from the sequential file name generation process used by Django's file upload handling system. When a file with a conflicting name is uploaded, Django appends a number to the file name to make it unique. However, this sequential process can be exploited by remote attackers to cause a denial of service. By uploading multiple files with the same name, the CPU consumption of the server increases significantly, leading to a potential service disruption. This vulnerability can be particularly damaging in scenarios where file uploads are frequent and large in size.

pip install --upgrade "django==6.1.2"

Workaround

If upgrading Django is not immediately feasible, a temporary workaround can be implemented by modifying the file upload handling code. Instead of relying on the default sequential file name generation, developers can implement a custom file naming scheme that ensures unique file names without relying on sequential numbering. Here is an example of a custom file naming function in Python:

import os

def generate_unique_filename(filename):
    base_name, ext = os.path.splitext(filename)
    counter = 1
    while os.path.exists(filename):
        filename = f'{base_name}_{counter}{ext}'
        counter += 1
    return filename

Conclusion

The sequential file name generation vulnerability in Django's file upload handling system can be exploited by remote attackers to cause a denial of service. It is crucial to update Django to versions 1.4.14, 1.5.9, 1.6.6, or later to mitigate this vulnerability. If immediate upgrade is not possible, developers can implement a custom file naming scheme as a temporary workaround. For further assistance and support in vulnerability remediation, please contact DevNack.com.

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