How zip files can hide risky files on macOS

What can hide inside a zip file?

• Shell scripts (.sh, .command) that run when opened.
• Compiled executables disguised with document icons.
• Nested archives, a zip inside a zip, that are easy to overlook.
• Symbolic links pointing to sensitive locations.
• Misleading extensions, such as report.pdf.app.

Why macOS does not always protect you

macOS has built-in protections such as Gatekeeper, but they do not cover everything:

• Gatekeeper checks apps, not every file type inside an archive.
• Quick Look previews may not reveal a file's true type.
• Finder hides extensions by default, which makes disguised files harder to spot.

How to handle archives safely

• Inspect the contents before extracting.
• Check file types and extensions carefully.
• Be cautious with archives from sources you do not know.
• Use a tool that shows you what is inside first.