Antivirus upgrade
An antivirus upgrade was a program upgrade designed to help a starship combat a computer virus.
In 2384, after the USS Protostar rendezvoused with the USS Voyager-A, Starfleet was able to render the living construct ineffective against their ships by using an antivirus upgrade developed with Starfleet's previous experience fighting the weapon and the chance to study it while the device was inactive. (PRO: "Ascension, Part I")