The 5 File Upload Vulnerability Mistakes You’re Making Right Now

November 18, 2021

Many industries and businesses allow – and even encourage – user-generated file uploads. Whether for health coverage, a mortgage, or an insurance policy, sometimes file uploads are essential. However, these file uploads must be treated with caution as they contain inherent risks. Read on to learn some of the file upload vulnerability mistakes you’re making, best practices for preventing attacks from file uploads, and why developing a secure file upload system is critical for avoiding costly data breaches.

Are You Making File Upload Vulnerability Mistakes?

Hackers have learned that it’s not always easy to breach the cyber-defenses of businesses. instead, they have found an easier way to inject malicious code into a target – by detecting a file upload vulnerability and embedding malicious content into the uploads. That means every time a customer, vendor, or other third-party uploads a file to your system, your entire network is at risk of being exploited. Hackers can easily identify organizations with file upload vulnerabilities. How? Here is a list of common mistakes.

Mistake 1: You Lack Authentication and Authorization

It’s all about permissions. Hackers can easily find a file upload vulnerability where there is no authentication or authorization check before a file can be uploaded, opening a door that allows malicious actors to unload any files they want. To avoid this scenario, ensure the user has been authenticated by signing in—preferably by using a user authentication protocol like two-factor authentication, which combines sign-in details with another security action like a security token.  This is so that it can be ensured the user has the correct permissions to upload a file to your system in the first place. 

Mistake 2: You’re Not True-Typing Your Files

Hackers can alter the file metadata to get the results they want. An altered file name or path can trick an application into changing the document’s security settings, overwriting a critical file, or executing malware on the network. Make sure you validate and sanitize a file’s metadata before allowing it to be uploaded. 

Mistake 3: You’re Not Checking the Contents of Your File

Checking the file’s name is not enough. You must investigate the content of the file as well. Uploaded file content can contain all kinds of malicious scripts that can wreak havoc on an organization.  Make sure that every single uploaded file is scanned with anti-malware tools. Note that not all tools are created equal. Antivirus scanners can miss new or zero-day threats that threat detection engines have not yet categorized. Some anti-malware tools can’t scan specific file types like PDFs or image files. Other anti-malware tools are unable to scan embedded objects that might be hiding in an uploaded file. Be sure to choose the best anti-malware tool for your needs. 

Mistake 4: You’re Storing Files in a Publicly Accessible Place

Many organizations make the common mistake of storing their files in a subsection of their website, such as in the Media directory. This makes it extremely easy for attackers to locate these files and target them. Uploaded files should be stored on external directories outside the website’s root, which will prevent hackers from accessing these files through a website URL.

Mistake 5: You’re Not Restricting Certain File Types

Certain file types should never be allowed to be uploaded to an organization’s network because they can execute commands and run malicious codes. For example, .php, .exe, and .bat files should be denylisted and rejected as a file upload. Even better, use an allowlist system that only allows certain file types to be uploaded, as the denylist risks missing an extension and being exploited. 

Prevent File Upload Vulnerabilities with Votiro

Unfortunately, even when these five file upload vulnerabilities are addressed, hackers may still have the upper hand when it comes to finding ways to sneak malicious code past your organization’s file security. Taking a zero-trust approach to file uploads – not trusting a single file or file element before it is uploaded to your environment – is the only answer.

Votiro’s API-first Content Disarm and Reconstruction solution, Secure File Gateway, first analyzes files for their true type, making sure that extensions and other signifiers match to what the file actually is. Then, the Secure File Gateway singles out only the safe elements of each file, rebuilding a new file with known safe content, and delivering that file to the end destination. Malicious code is proactively removed, with no scanning, no detection, and no blocking! Our Secure File Gateway analyzes all file types–from ppts, docs, PDFs, and image files, all the way to more complex formats like Autodesk files that antivirus scanners or other anti-malware tools could never detect.

To find out more about Votiro’s Secure File Gateway and its innovative approach to securing web uploads, schedule a demo with us today.