This can help determine if it's a known threat or a simple misunderstanding.

If you have already downloaded it, do not open it. Run a full system scan using your antivirus software (such as Windows Defender or other reputable security programs) specifically on that file.

If this file arrived via an unexpected email, chat message, or download, the safest action is to delete it immediately.

If you think the file might be legitimate, contact the sender through a different, trusted method (e.g., call them or email them directly) to confirm they sent it. Key Rule: Never trust unexpected attachments. If you can, tell me: How you received this file (email, chat, download)? What is the file size ?