A Trojan is a program that gives the attacker full control over the infected computer, thus allowing the attacker to hijack, copy or alter information after authentication by the user. IP spoofing will not work because IP is not used as an authentication mechanism. Man-in-the-middle attacks are not possible if using SSL with client-side certificates. Repudiation is unlikely because client-side certificates authenticate the user.

Explanation
Server-based malware protection is not enforced is the issue that would be of GREATEST concern to an information security manager, as it exposes the web-based application and its data to potential threats from malicious software that can compromise the confidentiality, integrity, and availability of the information.
Server-based malware protection is a security control that monitors and blocks malicious activities on the server where the application runs, such as viruses, worms, trojans, ransomware, etc. Without server-based malware protection, the web-based application may be vulnerable to attacks that can damage or destroy the data stored on the server, or disrupt the normal functioning of the application. The other issues are also important, but not as critical as server-based malware protection. The application does not use a secure communications protocol may expose sensitive data in transit to eavesdropping or interception by unauthorized parties. The application is configured with restrictive access controls may limit the access rights of legitimate users to authorized resources, but it does not prevent unauthorized users from accessing them through other means. The business process has only one level of error checking may result in incorrect or inconsistent data entry or processing, but it does not guarantee data quality or accuracy. References = CISM Review Manual, 16th Edition, page 1751; CISM Review Questions, Answers & Explanations Manual, 10th Edition, page 812

Assigning a risk owner is the best way to ensure a risk response plan will be developed and executed in a timely manner, because a risk owner is responsible for monitoring, controlling, and reporting on the risk, as well as implementing the appropriate risk response actions. A risk owner should have the authority, accountability, and resources to manage the risk effectively. Establishing risk metrics, training on risk management procedures, and reporting on documented deficiencies are all important aspects of risk management, but they do not guarantee that a risk response plan will be executed promptly and properly. Risk metrics help to measure and communicate the risk level and performance, but they do not assign any responsibility or action. Training on risk management procedures helps to increase the awareness and competence of the staff involved in risk management, but it does not ensure that they will follow the procedures or have the authority to do so. Reporting on documented deficiencies helps to identify and communicate the gaps and weaknesses in the risk management process, but it does not provide any solutions or corrective actions. Reference = CISM Review Manual, 16th Edition, ISACA, 2021, pages 125-126, 136-137.