Visual Basic User-defined Control file
application/octet-stream
Magic Bytes
Offset: 0
56 65 72 73 69 6F 6E 20
The Visual Basic User-defined Control file is a proprietary source code format developed by Microsoft for the Visual Basic development environment. It defines the graphical layout and functional logic for reusable ActiveX components, allowing developers to create custom interface elements for Windows software. This text-based format is now considered legacy following the industry shift toward the .NET framework, though it remains relatively safe due to its non-executable source structure.
Validation Code
How to validate .ctl files in Python
Python
def is_ctl(file_path: str) -> bool:
"""Check if file is a valid CTL by magic bytes."""
signature = bytes([0x56, 0x65, 0x72, 0x73, 0x69, 0x6F, 0x6E, 0x20])
with open(file_path, "rb") as f:
return f.read(8) == signatureHow to validate .ctl files in Node.js
Node.js
function isCTL(buffer: Buffer): boolean {
const signature = Buffer.from([0x56, 0x65, 0x72, 0x73, 0x69, 0x6F, 0x6E, 0x20]);
return buffer.subarray(0, 8).equals(signature);
}
Go
func IsCTL(data []byte) bool {
signature := []byte{0x56, 0x65, 0x72, 0x73, 0x69, 0x6F, 0x6E, 0x20}
if len(data) < 8 {
return false
}
return bytes.Equal(data[:8], signature)
}API Endpoint
GET
/api/v1/ctl
curl https://filesignature.org/api/v1/ctl