File upload vulnerabilities occur when an application allows a user to upload a file, such as a picture or a document, to a server. If the application does not correctly validate the file, an attacker may be able to upload a malicious file that could compromise the server's security. This can allow the attacker to execute arbitrary code on the server, or to access sensitive information stored on the server.
Several types of attacks can be used to exploit file upload vulnerabilities. For example, an attacker may try to upload a file that contains malicious code, such as a PHP script or an executable file. The attacker could then access the file from the server and execute the code, potentially gaining access to sensitive data or taking control of the server.
Another type of attack that can be used to exploit file upload vulnerabilities are called "cross-site scripting" (XSS). This type of attack involves injecting malicious code into a website, which is then executed by the victim's web browser. If a user is tricked into uploading a file that contains XSS code, the code could be executed on the server and potentially compromise the security of the system.
Set up DVFU
Let's go straight to demonstrate file upload vulnerability using the Damn Vulnerable File Upload Lab web application. Damn Vulnerable File Upload Lab is designed to practice File Upload vulnerabilities. Before getting started, our first priority is to set up this web application within our local machine.
Follow the below steps to set up the server:
1. To set up the File Upload Lab web application, firstly, we have to clone it from GitHub.
2. Now, we will have to copy the DVFU directory to the web directory.
3. Now, let me run the apache2 service.
4. Once the Apache2 service starts, we can easily access the web application through any browser.
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If you have noticed, we are presented with various levels of an HTML form that asks us to upload a file.
