what is zip bomb

A Zip Bomb, also known as Zip of Death or Decompression Bomb,
 is a malicious archive file. When uncompressed, it expands dangerously,
 requiring large amounts of time, disk space and memory,
 causing the system to crash.

zip bomb

 Usually it's a small file, only up to a few hundred kylobytes,
 in the form of a loop,
which will continuosly unpack itself until all system resources are exhausted.
It's designed in order to disable the antivirus software,
 so that a more traditional virus sent afterwards could get into the system
wihtout being detected.