Eliza (computer virus)

Eliza is a computer virus that surfaced in the early 1990s. It is a relatively simple virus that primarily infects DOS systems. Eliza is a file infector, meaning it attaches itself to executable files (typically .COM and .EXE files) and spreads when those infected files are executed.

The virus operates by appending its code to the end of the host file. When an infected program is run, Eliza's code is executed first. This code then attempts to infect other executable files in the current directory or on the system's path. After attempting to spread, the virus typically passes control back to the original host program, allowing it to execute as intended, making the infection less obvious to the user.

Eliza is not considered particularly destructive. Its primary function is to replicate itself. However, like any virus, its presence can lead to instability due to the altered file sizes and potential conflicts with other software. Infected files may also exhibit slower performance due to the additional code being executed. Furthermore, its replication process can consume system resources, although this is generally minimal with Eliza.

Variants of the Eliza virus have been identified, sometimes exhibiting slight variations in their infection methods or the messages they may display. While once prevalent, Eliza has largely faded from prominence due to the obsolescence of DOS and the widespread adoption of more sophisticated anti-virus software. However, it remains a notable example of early file-infecting viruses.