【File Upload Vulnerability】Impact and Prevention
Nov 16, 2022
9 min read
In this article:
One of the core features of modern web systems is file uploads that allow users to transmit files from client applications to the server machine. Although the feature is considered crucial for applications that operate on user-generated content, a file upload vulnerability causes a web server to accept user-submitted files without checking for attributes such as the type, size, name, or content. In such vulnerable servers, attackers can upload malicious files that can potentially affect the web application’s availability, functionality, and data integrity.
This article discusses a file upload vulnerability, its potential impacts on modern application delivery, and effective prevention strategies.
What Is File Upload Vulnerability?
A file upload vulnerability allows attackers to inject malicious content into the application server. Also known as an unrestricted file upload, an attack is triggered by either tricking a victim user into uploading an arbitrary file or by uploading it directly through a file upload service that does not validate the type of file used.
File upload vulnerabilities are categorized according to the file attribute the application fails to validate. These include:
Insufficient file type restrictions – If the web server fails to validate the content and file extension, attackers can upload files containing executable scripts that allow for remote code execution and