This paper examines how user communities and technological practices shaped distinctive conceptions of antivirus software in post-Socialist China from 1989 to 2010. Drawing on IT magazines, handbooks, journal articles, online forums, and official publications, we highlight three metaphors and meanings for antivirus software –a tool, a “doctor,” and a “hooligan” – arguing that these metaphors reflected evolving relations between the antivirus industry and computer users. This paper contributes to two understudied areas of the history of computing. First, we build upon a small but crucial body of scholarship on the history of the computer security industry, which to date has focused primarily on the United States. Second, by centering our analysis on user communities in China, we broaden the dominant focus of computing historiography in China and East Asia, which has instead emphasized the achievements and activities of state institutions.