Windows Installer Patch magic bytes (.msp)
.msp file signature: D0 CF 11 E0 A1 B1 1A E1 | application/x-ms-installer
Windows Installer Patch (MSP) is a patch package format created and maintained by Microsoft for updating software installed through Windows Installer. It is used to apply fixes, feature updates, and administrative changes to existing applications, commonly alongside enterprise deployment and software maintenance tools. Because patches can modify installed programs and may run with elevated privileges, files from untrusted sources should be handled cautiously; the format remains in use but is largely associated with legacy Windows deployment workflows.
High Risk Format
This file type can contain executable code. Always validate the source and scan with antivirus before opening.
Magic Bytes
Offset 0
D0 CF 11 E0 A1 B1 1A E1
Sources: Gary Kessler
Validation Code
How to validate .msp files in Python
def is_msp(file_path: str) -> bool:
"""Check if file is a valid MSP by magic bytes."""
signature = bytes([0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1])
with open(file_path, "rb") as f:
return f.read(8) == signatureHow to validate .msp files in Node.js
function isMSP(buffer: Buffer): boolean {
const signature = Buffer.from([0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1]);
return buffer.subarray(0, 8).equals(signature);
}How to validate .msp files in Go
func IsMSP(data []byte) bool {
signature := []byte{0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1}
if len(data) < 8 {
return false
}
return bytes.Equal(data[:8], signature)
}API Endpoint
/api/v1/msp
curl https://filesignature.org/api/v1/msp
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .msp file?
A .msp file is a Windows Installer Patch file. Windows Installer Patch (MSP) is a patch package format created and maintained by Microsoft for updating software installed through Windows Installer. It is used to apply fixes, feature updates, and administrative changes to existing applications, commonly alongside enterprise deployment and software maintenance tools. Because patches can modify installed programs and may run with elevated privileges, files from untrusted sources should be handled cautiously; the format remains in use but is largely associated with legacy Windows deployment workflows.
What are the magic bytes for .msp files?
The magic bytes for Windows Installer Patch (.msp) files are D0 CF 11 E0 A1 B1 1A E1 at byte offset 0. These bytes identify the file format more reliably than the extension alone.
How do I validate a .msp file?
To validate a .msp file, read the first bytes of the file and compare them against the known magic bytes (D0 CF 11 E0 A1 B1 1A E1) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .msp files?
The primary MIME type for .msp files is application/x-ms-installer.
Is it safe to open .msp files?
Windows Installer Patch (.msp) files are high risk because they can contain executable code. Never open .msp files from untrusted sources. Always scan with antivirus software, verify the source, and consider running in a sandboxed environment.