Modernized information systems (IS) have brought enterprises not only enormous benefits, but also linked information threats. Most enterprises solve their IS security-related problems using technical means alone, and focus on technical rather than managerial controls, which may imply potential crises. This study examines whether the security preparation of Taiwan's firms matches the severity of IS threats they perceive, especially in issues concerning 'people' and 'administration'. The empirical data was provided by 109 Taiwan's enterprises from four industries. The analytical results revealed differences in both the IS threats concerned and the security scopes prepared among the four sectors. Moreover, the preparation scopes were not commensurate with the perceived severity of threats. All four industries rated the network as posing the strongest threat, followed by regulation and personnel issues, while among the countermeasures in use, these three issues have larger application deficiencies. This study concludes that firms do not well prepare themselves against IS threats entailed to non-technical administration issues and discusses appropriate threat mitigation strategies for an firm in the four sectors and with the three levels of computerization. Specifically, firms should be aware of IS threats to their business and prepare suitable security protections.