1260, or V2PX, was 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...

 written in 1989 by Mark Washburn that used a form of polymorphic encryption

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...

. Derived from Ralph Burger's publication of the disassembled

Reverse engineering

Reverse engineering is the process of discovering the technological principles of a device, object, or system through analysis of its structure, function, and operation...

 Vienna virus source code, the 1260 altered its signature by randomizing

Randomization

Randomization is the process of making something random; this means:* Generating a random permutation of a sequence .* Selecting a random sample of a population ....

 and obfuscating its decryption algorithm in an effort to keep its signature length short and variable. Both the 1260 and Vienna infect .COM

.com

The domain name com is a generic top-level domain in the Domain Name System of the Internet. Its name is derived from commercial, indicating its original intended purpose for domains registered by commercial organizations...

 files in the current or PATH

Path (variable)

PATH is an environment variable on Unix-like operating systems, DOS, OS/2, and Microsoft Windows, specifying a set of directories where executable programs are located...

directories upon execution.