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MS Exchange 2007 extended configuration file (.ecf)

.ecf file signature | application/octet-stream

The ECF file format is an extended configuration file used by Microsoft Exchange Server 2007, created and maintained by Microsoft. It is used to store administrative settings and deployment-related configuration data for Exchange 2007 environments and associated tools. As a legacy format tied to an older Exchange release, it is primarily of historical interest and should be handled cautiously when opening files from untrusted sources.

Safe

Magic Bytes

Offset 0
5B 47 65 6E 65 72 61 6C 5D 0D 0A 44 69 73 70 6C 61 79 20 4E 61 6D 65 3D 3C 44 69 73 70 6C 61 79 4E 61 6D 65

Sources: Gary Kessler

Extension

.ecf

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .ecf files in Python

Python 
def is_ecf(file_path: str) -> bool:
    """Check if file is a valid ECF by magic bytes."""
    signature = bytes([0x5B, 0x47, 0x65, 0x6E, 0x65, 0x72, 0x61, 0x6C, 0x5D, 0x0D, 0x0A, 0x44, 0x69, 0x73, 0x70, 0x6C, 0x61, 0x79, 0x20, 0x4E, 0x61, 0x6D, 0x65, 0x3D, 0x3C, 0x44, 0x69, 0x73, 0x70, 0x6C, 0x61, 0x79, 0x4E, 0x61, 0x6D, 0x65])
    with open(file_path, "rb") as f:
        return f.read(36) == signature

How to validate .ecf files in Node.js

Node.js 
function isECF(buffer: Buffer): boolean {
  const signature = Buffer.from([0x5B, 0x47, 0x65, 0x6E, 0x65, 0x72, 0x61, 0x6C, 0x5D, 0x0D, 0x0A, 0x44, 0x69, 0x73, 0x70, 0x6C, 0x61, 0x79, 0x20, 0x4E, 0x61, 0x6D, 0x65, 0x3D, 0x3C, 0x44, 0x69, 0x73, 0x70, 0x6C, 0x61, 0x79, 0x4E, 0x61, 0x6D, 0x65]);
  return buffer.subarray(0, 36).equals(signature);
}

How to validate .ecf files in Go

Go 
func IsECF(data []byte) bool {
    signature := []byte{0x5B, 0x47, 0x65, 0x6E, 0x65, 0x72, 0x61, 0x6C, 0x5D, 0x0D, 0x0A, 0x44, 0x69, 0x73, 0x70, 0x6C, 0x61, 0x79, 0x20, 0x4E, 0x61, 0x6D, 0x65, 0x3D, 0x3C, 0x44, 0x69, 0x73, 0x70, 0x6C, 0x61, 0x79, 0x4E, 0x61, 0x6D, 0x65}
    if len(data) < 36 {
        return false
    }
    return bytes.Equal(data[:36], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .ecf file?

A .ecf file is a MS Exchange 2007 extended configuration file file. The ECF file format is an extended configuration file used by Microsoft Exchange Server 2007, created and maintained by Microsoft. It is used to store administrative settings and deployment-related configuration data for Exchange 2007 environments and associated tools. As a legacy format tied to an older Exchange release, it is primarily of historical interest and should be handled cautiously when opening files from untrusted sources.

What are the magic bytes for .ecf files?

The magic bytes for MS Exchange 2007 extended configuration file files are 5B 47 65 6E 65 72 61 6C 5D 0D 0A 44 69 73 70 6C 61 79 20 4E 61 6D 65 3D 3C 44 69 73 70 6C 61 79 4E 61 6D 65 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .ecf file?

To validate a .ecf file, read the first bytes of the file and compare them against the known magic bytes (5B 47 65 6E 65 72 61 6C 5D 0D 0A 44 69 73 70 6C 61 79 20 4E 61 6D 65 3D 3C 44 69 73 70 6C 61 79 4E 61 6D 65) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .ecf files?

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

Is it safe to open .ecf files?

MS Exchange 2007 extended configuration file (.ecf) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.