๐ ๐ผ๐ฑ๐ฒ๐ฟ๐ป ๐๐ฟ๐ฎ๐บ๐ฒ๐๐ผ๐ฟ๐ธ๐ ๐๐ฟ๐ฒ ๐ก๐ผ๐ ๐๐บ๐บ๐๐ป๐ฒ ๐ง๐ผ ๐๐๐
You use a modern framework. You think it handles security. This is a lie.
Spring Boot and Django are great. They stop common attacks. But they only protect the paths they know.
They do not protect your custom code.
Local File Inclusion (LFI) is still a threat. It hides in your custom business logic. It lives in your file downloaders and module loaders.
LFI happens when your app uses user input to find a file. If you do not check the path, a hacker escapes the folder.
Example: Safe: /view?file=report.pdf Dangerous: /view?file=../../../../etc/passwd
The dots move up the folder tree. The hacker reads your system files.
The risks are high:
- Stolen passwords
- Leaked API keys
- Source code exposure
- Remote code execution
You write a custom controller. You use Paths.get(). You forget to normalize the path. You check for dots, but hackers use encoding to bypass you.
How to fix it:
- Use .toRealPath() in Java.
- Verify the file starts with your base folder.
- Use a whitelist of allowed files.
- Strip path parts from filenames.
Search your code for these:
- getParameter with file or path
- Paths.get() without normalization
- readAllBytes with user input
Professional code still has old bugs. Your architecture looks modern, but your flaw is ancient.
Check your filesystem calls now.