The Whale virus is a computer virus

Computer virus

A computer virus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly but erroneously used to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability...

 discovered on July 1, 1990. The file size, at 9,216 byte

Byte

The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...

s, was for its time the largest virus ever discovered. It was written by German programmer R. Horner. It is known for using several advanced "stealth" methods.

After the file becomes resident in the system memory below the 640k DOS boundary, the operator will experience total system slow down as a result of the virus' polymorphic code

Polymorphic code

In computer terminology, polymorphic code is code that uses a polymorphic engine to mutate while keeping the original algorithm intact. That is, the code changes itself each time it runs, but the function of the code will not change at all...

. Symptoms include video flicker to the screen writing very slowly. Files may seem to "hang" even though they will eventually execute correctly. This is just a product of the total system slow down within the system's memory.

It was reported that one infected program displayed the following message when run:

THE WHALE IN SEARCH OF THE 8 FISH

I AM '~knzyvo}' IN HAMBURG addr error D9EB,02