embedded file signatures

• PK: ZIP
• MZ: Windows Executable (PE format)
• GIF87a / GIF89a: GIF images
• 89 50 4E 47 0D 0A 1A 0A: PNG header. \x89PNG
• JFIF: often seen inside JPEG files, although JPEGs tend to have lots of other headers that vary
• 52 61 72 21: RAR archive signature for RAR 1.5 tp 4.0. different for newer versions
• 37 7A BC AF 27 1C: 7z file header
• ID3: MP3 files sometimes have this tag at the start