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UCAS (.ucas)

.ucas file signature | application/octet-stream

UCAS is an Unreal Engine compressed asset storage format developed and maintained by Epic Games for packaging game content. It is used with Unreal Engine projects to store assets such as textures, sounds, and other runtime data in distributable game builds and editor-managed packages. The format is generally safe, though files from untrusted sources should be handled cautiously because they may contain large binary assets used by modded or modified games.

Safe

Magic Bytes

Offset 0
8C 0A 00

Sources: Wikipedia

Extension

.ucas

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .ucas files in Python

Python 
def is_ucas(file_path: str) -> bool:
    """Check if file is a valid UCAS by magic bytes."""
    signature = bytes([0x8C, 0x0A, 0x00])
    with open(file_path, "rb") as f:
        return f.read(3) == signature

How to validate .ucas files in Node.js

Node.js 
function isUCAS(buffer: Buffer): boolean {
  const signature = Buffer.from([0x8C, 0x0A, 0x00]);
  return buffer.subarray(0, 3).equals(signature);
}

How to validate .ucas files in Go

Go 
func IsUCAS(data []byte) bool {
    signature := []byte{0x8C, 0x0A, 0x00}
    if len(data) < 3 {
        return false
    }
    return bytes.Equal(data[:3], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .ucas file?

A .ucas file is identified by the magic bytes 8C 0A 00 at byte offset 0. UCAS is an Unreal Engine compressed asset storage format developed and maintained by Epic Games for packaging game content. It is used with Unreal Engine projects to store assets such as textures, sounds, and other runtime data in distributable game builds and editor-managed packages. The format is generally safe, though files from untrusted sources should be handled cautiously because they may contain large binary assets used by modded or modified games.

What are the magic bytes for .ucas files?

The magic bytes for UCAS files are 8C 0A 00 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .ucas file?

To validate a .ucas file, read the first bytes of the file and compare them against the known magic bytes (8C 0A 00) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .ucas files?

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

Is it safe to open .ucas files?

UCAS (.ucas) 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.