PNG disguise is a form of file-type masquerading where malicious content is presented as a PNG image to look harmless. The trick may involve naming a payload with a .png extension, serving it with image-like metadata, or placing non-image data inside a container that resembles a normal picture file. The goal is to make users, browsers, and some security tools treat it as ordinary web content.
This matters because defenders often prioritize obvious executables, scripts, and attachments, while image files are usually low-risk in triage. In real attacks, PNG disguise can help payloads blend into browser cache, downloads, or content delivery paths, delaying inspection and reducing suspicion. Security teams counter it by checking file signatures, MIME type mismatches, unexpected script or archive content, and suspicious behavior after opening. The key lesson is that the filename alone does not prove a file is safe.