Hackers frequently exploit file upload flaws to transmit malware, obtain access to web servers, launch attacks on website visitors, host illegal content, and more.
Existing important files can thus be replaced, with the. htaccess file implanted to run specified scripts. Inject phishing pages into the web application to make it look bad. Error messages containing vital internal information, such as server-specific paths, may be exposed during file uploads.
Make changes to the "php. ini" file.
Make sure the file doesn't already exist. We can now add some constraints.
Set a file size limit. "fileToUpload" is the name of the file input box in our HTML form above.
Set a file type limit.
Upload File PHP Script in Its Entirety
The majority of file uploads are designed to remain inert. Unless you're creating a very specific type of website, you're more likely to get photographs, videos, or document files instead of executable code. If this is the case, separating uploaded files from application code is a critical security factor.
When a web server lets users to upload files to its filesystem without properly validating things like their name, type, contents, or size, it creates file upload vulnerabilities.
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