It uses recursive compression . The main file contains 16 zipped files; each of those contains another 16, and so on, through five layers. The final layer contains a single 4.3 GB file filled entirely with zeros.
The legendary is a classic example of a zip bomb (or "decompression bomb"), a malicious archive designed to crash or disable a system by overloading its resources during extraction. What is 42.zip? 42.zip
Traditionally, zip bombs were used to target antivirus software . When a scanner tries to "look inside" the archive to check for viruses, it might attempt to decompress the layers, exhausting the system's memory or CPU. Useful Blog Posts & Resources It uses recursive compression