4D5A Security is named after the hexadecimal representation of the two ASCII characters “MZ”, initials for Mark Zbikowski, who lead development of MS-DOS and the “magic number” seen in the header of any executable file on Windows. If you’re a threat hunter you’re looking for “MZ” in ASCII or “4D 5A” in ‘hex’ to confirm its an executable as part of content inspection when looking for hostile executables like that of malware.

The 4D5A logo is composed of two letters, M and Z, manipulated within an image program to create the image you see today: