Explanation/Reference:
Explanation:
The effectiveness of virus detection software depends on virus signatures which are stored in virus definition tables. Software upgrades are related to the periodic updating of the program code, which would not be as critical. Intrusion detection and packet filtering do not focus on virus detection.

Risk assessment first requires one to identify the business assets that need to be protected before identifying the threats. The next step is to establish whether those threats represent business risk by identifying the likelihood and effect of occurrence, followed by assessing the vulnerabilities that may affect the security of the asset. This process establishes the control objectives against which key controls can be evaluated.