There is no denying that file upload is an essential operation. It is a feature that all your users want to have access to. However, file upload can pose serious security threats and dangers to your system.
What Are The Top Security Hazards Of File Upload?
Here are some of the top security hazards of file upload:
1. Are There Specific File Types That Pose A Threat?
If you are building your server, you should be wary of different file types and their potential risk to the security of your system.
For example, many files with extensions such as .exe, .bat, .cmd, and more can contain executable scripts. An attacker can upload such a file with malicious content and easily execute that script on your system.
Hence, an attacker can upload a dangerous executable file to your system and gain access to your server. A decent way to circumvent this problem is to block all files with such extensions.
However, there is always the danger that you may not have an exhaustive list of such extensions. Missing out on them can lead to a security breach.
2. Is There A Way For An Attacker To Launch A Server-Side Attack Through File Upload And Overwriting An Existing File?
Indeed, yes. Suppose there is an essential file for the normal operations of a server. Next, an attacker comes and successfully uploads a file with the same name and extension. Finally, you would overwrite the file.
The above scenario can lead to dangerous consequences, allowing the attacker to gain complete control of the server. For example, the attacker can overwrite other files on the server, change its security settings, delete existing data, access critical information, and more. This way, the entire website can collapse.
3. How Does File Size Pose A Denial of Service (DoS) Attack Threaten The System?
The Denial of Service (DoS) attack is intended to make a server, machine, or website inaccessible to its users. One way of accomplishing this is by simultaneously uploading many large files to the server.
This can overwhelm the server with high volumes of traffic, leading to the inability of the server to handle requests from genuine users. Therefore, the users will be unable to access the server or the corresponding website.
4. Can Anyone Access My File Containing Sensitive Data Through A Snooping Attack?
A snooping attack, among other things, can also involve an eavesdropper listening to communication between two machines.
If you have a file containing sensitive information, such as your credit card information or personal data, it can be accessed during file upload through a snooping attack. This can lead to a dangerous situation, as all your data can fall into the wrong hands.
5. Can MIME Sniffing Lead To XSS Attacks?
XSS stands for cross-site scripting. In an XSS attack, a hacker injects malicious code into a resource and executes this code at the client end. MIME sniffing is a method through which web browsers determine the type of file or resource by analyzing and examining its contents.
Let’s say a website allows its users to upload files or data to the website. An attacker can hide malicious code in an allowed file type.
Once this file is uploaded, the server starts the process of MIME sniffing to analyze its contents. The hidden code can be executed due to MIME sniffing, making the site vulnerable to a potential XSS attack.
How Do I Prevent Security Hazards Posed By File Upload?
There are several ways to prevent security hazards posed by file uploads. Some of them are listed below:
- You must keep an updated copy of an antivirus program running on your system.
- Always authenticate users and validate their identities. Two-factor authentication can help prevent potential threats.
- Maintain a list of file types you allow for upload and block the rest. This prevents attackers from uploading malicious files to your server.
- Set a maximum length for filenames and a maximum limit on the file size a user can try to upload to a server.
- Ensure you store files containing sensitive data in directories that can access through secure passwords. You should keep all other files outside the web root folders. Allow users to upload files to a website’s public directory.
- Ensure all file exchanges take place over a secure connection to prevent snooping attacks. This is essential when transmitting files that contain sensitive data. Also, make sure you have up-to-date software that encrypts these files.
- Verify all file types to ensure you are not allowing files containing malicious executable script or code.
If you are a developer, you already know the value of reusing code that eliminates the need for reinventing the wheel. Take, for example, professionally written, tried, and tested APIs for file uploads.
What Are The Key Takeaways Regarding File Upload Hazards?
File uploads can pose dangerous security risks to your system. For example, they can allow attackers to eavesdrop and access sensitive data. Additionally, in extreme circumstances, hackers can disrupt your website’s services or take complete control of your server.
You can take a few steps to prevent significant security hazards from file uploads.
These include authenticating users, using anti-virus software, keeping your admin and data-sensitive directories secure, allowing certain file types and blocking others, and more.
Apart from this, it is best to use professionally written, tried, and tested APIs for secure JS file uploads and to keep your system safe.