Viruses are infections in a computer system, usually self-replicating and inclined to spread, which cause the system to malfunction in various ways. In the TRON Universe, virally infected programs have lemon-yellow or greenish-yellow circuitry.
TRON: Evolution featured a vicious, devastating virus called Abraxas. Abraxas was a former ISO named Jalen, who was reprogrammed by Clu in order to persuade Basics that the ISOs were a threat. Abraxas infected many programs, including Gibson; those programs became known as the Infected.
While most visible and widespread viral devastation in the TRON universe was caused by infected programs, viral (though non-self-replicating) behavior is also seen in the pathogenic code used in TRON: Uprising to infect programs with dormant personality changes, and in Cyrus's dummy identity disc, infected with a virus which electrocuted Beck when he tried to dock it and, despite a quarantine forcefield, managed to break free and compromise Tron's safehouse.
In TRON 2.0 continuity, a viral infection is caused by J.D. Thorne as a result of his digitizing without the correction algorithms. Thorne himself turned into a virus, and, calling himself a "Master User," he spread this corruption through the ENCOM systems by infecting programs.
TRON 2.0 also has other types of viruses:
- Z-Lots are simple viruses. They are usually easy to kill, but they swarm in the masses. They are either created by direct infection, or spawned in by Rector Scripts.
- Rector Scripts are more complex viruses. They are very hard to kill, but a headshot with a disc will derez them immediately. They can spawn in Z-Lots, making them even harder to attack.
The main weapons of viruses in TRON 2.0 are Balls. Balls are glowing, green blobs of data that have corrosive and infective properties. Through subroutines, different ball-based weaponry can be used, such as the Ball Launcher and Drunken Dims.