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Screen saver (.scr)

.scr file signature | application/octet-stream

Screen saver (SCR) is a Microsoft Windows file format for screen saver applications, maintained as part of the Windows executable ecosystem. It is used for animated idle displays, password-protected lock screens, and installer-distributed visual effects on legacy and current Windows systems. Because it is executable code rather than a passive media format, SCR files can carry the same security risks as other Windows programs and should be opened only from trusted sources.

High

Magic Bytes

Offset 0
4D 5A

Sources: Wikipedia, Gary Kessler

Extension

.scr

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

High

Validation Code

How to validate .scr files in Python

Python 
def is_scr(file_path: str) -> bool:
    """Check if file is a valid SCR by magic bytes."""
    signature = bytes([0x4D, 0x5A])
    with open(file_path, "rb") as f:
        return f.read(2) == signature

How to validate .scr files in Node.js

Node.js 
function isSCR(buffer: Buffer): boolean {
  const signature = Buffer.from([0x4D, 0x5A]);
  return buffer.subarray(0, 2).equals(signature);
}

How to validate .scr files in Go

Go 
func IsSCR(data []byte) bool {
    signature := []byte{0x4D, 0x5A}
    if len(data) < 2 {
        return false
    }
    return bytes.Equal(data[:2], signature)
}

API Endpoint

GET /api/v1/scr
curl https://filesignature.org/api/v1/scr

See the full API documentation for all endpoints and parameters.

Related Formats

.com .cpl .dll .exe .ocx .sys

Frequently Asked Questions

What is a .scr file?

A .scr file is a Screen saver file. Screen saver (SCR) is a Microsoft Windows file format for screen saver applications, maintained as part of the Windows executable ecosystem. It is used for animated idle displays, password-protected lock screens, and installer-distributed visual effects on legacy and current Windows systems. Because it is executable code rather than a passive media format, SCR files can carry the same security risks as other Windows programs and should be opened only from trusted sources.

What are the magic bytes for .scr files?

The magic bytes for Screen saver files are 4D 5A at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .scr file?

To validate a .scr file, read the first bytes of the file and compare them against the known magic bytes (4D 5A) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .scr files?

There is no officially registered MIME type for .scr files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .scr files?

Screen saver (.scr) files are high risk because they can contain executable code. Never open .scr files from untrusted sources. Always scan with antivirus software, verify the source, and consider running in a sandboxed environment.