This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.
Indication of Infection
If the script is launched on the 17th day of the month a message box appears which reads, "Manuela|by Manuela/Tiers".
Methods of Infection
Executing the script overwrites all files in the same directory as the script.