MUI
application/octet-stream
Magic Bytes
Offset: 0
4D 5A
Multilingual User Interface (MUI) is a resource file format developed and maintained by Microsoft for the Windows operating system. These files store localized strings, icons, and menus separately from the application code, allowing for the dynamic switching of interface languages without modifying core binaries. While technically structured as executable binaries, they are generally considered safe because they contain non-executable data and are verified by the system's resource management framework.
Validation Code
How to validate .mui files in Python
Python
def is_mui(file_path: str) -> bool:
"""Check if file is a valid MUI by magic bytes."""
signature = bytes([0x4D, 0x5A])
with open(file_path, "rb") as f:
return f.read(2) == signatureHow to validate .mui files in Node.js
Node.js
function isMUI(buffer: Buffer): boolean {
const signature = Buffer.from([0x4D, 0x5A]);
return buffer.subarray(0, 2).equals(signature);
}
Go
func IsMUI(data []byte) bool {
signature := []byte{0x4D, 0x5A}
if len(data) < 2 {
return false
}
return bytes.Equal(data[:2], signature)
}API Endpoint
GET
/api/v1/mui
curl https://filesignature.org/api/v1/mui