Runners, especially those of the Anarch persuasion, often infect corporate servers with malicious viruses. Noise, in particular, is known for his talent with viruses. Viruses can serve a variety of purposes, ranging from outright destruction, to information gathering, sabotage, and even as functional icebreakers.
The Parasite virus slowly degrades a targeted piece of ice over time, eventually reducing it to nothing. Meanwhile, Imp can instantly corrupt data that the Runner gains access to, immediately sending it to Archives.
Information Gathering VirusesEdit
Some viruses are designed for the 'harmless' task of collecting information. For example, Deep Thought infects R&D servers and sends information to the Runner regarding developing projects that are close to completion. Medium actively mines data from infected R&D servers (masking its activity as random packet loss), providing the Runner with a deeper look into future corporate projects when the Runner accesses the R&D server. Nerve Agent carries out a similar function to Medium except it is designed to infect HQ servers. Meanwhile, Datasucker is more versatile, able to collect network security information from central servers, providing critical information that can help the Runner overcome server defences during future attacks.
A few viruses are meant for outright sabotage. Pheremones undermines HQ server security, enabling easier access to the HQ server each time the Runner accesses it. The Hemorrhage virus bleeds data from the HQ network and into Archives. Meanwhile, Chakana sabotages R&D servers, slowing project development to a crawl. Inspired by Gus Gorman from the movie Superman III, the Gorman Drip v1 virus drains fractions of currency from corporate accounts into the Runner's. The Lamprey virus destroys financial data, potentially wrecking corporate bank accounts.
Known virus-based A.I. icebreakers are Crypsis and Darwin.