Residual risk is the risk that remains after the risk mitigation plans have been implemented. Residual risk reflects the effectiveness of the risk response in reducing the likelihood or impact of the risk. The best evidence that risk mitigation plans have been implemented effectively is the change in the level of residual risk. A change in the level of residual risk can be measured by comparing the risk level before and after the risk mitigation plans have been executed. A change in the level of residual risk can also be evaluated by comparing the actual residual risk with the target or acceptable residual risk. A change in the level of residual risk can demonstrate how well the risk mitigation plans have achieved the risk objectives and met the risk criteria. A change in the level of residual risk can also provide feedback and lessons learned for future risk management activities. References = Residual Risk: Definition, Formula & Management, Residual Risk:
What It Is and How to Manage It, Residual Risk: How to Calculate and Manage It.

A managed security service provider (MSSP) is a third-party entity that offers network security services to an organization, such as firewall operation, administration, monitoring, and maintenance1. A firewall is a device or software that controls the incoming and outgoing network traffic based on predefined rules2. A firewall administrator is a person or entity that manages and maintains the firewall configuration, rules, and policies3. When an organization uses an MSSP as a firewall administrator, the greatest concern is the exposure of log data, because log data contains sensitive and valuable information about the organization's network activity, such as source and destination IP addresses, ports, protocols, timestamps, and user identities4. If the log data is not protected properly by the MSSP, it could be accessed, modified, or stolen by unauthorized parties, such as hackers, competitors, or regulators, which could result in data breaches, compliance violations, reputational damage, or legal liabilities for the organization5. The other options are not as concerning as the exposure of log data, because they do not pose a direct and immediate threat to the organization's data security and privacy, but rather affect the quality and efficiency of the firewall management, as explained below:
* B. Lack of governance is a concern when an organization uses an MSSP as a firewall administrator, because it could lead to misalignment or inconsistency between the organization's and the MSSP's objectives, policies, and standards for firewall management. However, this concern can be mitigated by establishing a clear and comprehensive service level agreement (SLA) with the MSSP, which defines the roles, responsibilities, expectations, and performance indicators for the firewall management service6.
* C. Increased number of firewall rules is a concern when an organization uses an MSSP as a firewall administrator, because it could create complexity, confusion, or duplication in the firewall configuration, which could affect the firewall performance and security. However, this concern can be mitigated by conducting regular firewall audits and reviews with the MSSP, which can help to rationalize, optimize, and update the firewall rules, and to ensure that they are relevant, effective, and efficient for the organization's network environment.
* D. Lack of agreed-upon standards is a concern when an organization uses an MSSP as a firewall administrator, because it could result in gaps or weaknesses in the firewall design and implementation, which could compromise the firewall functionality and security. However, this concern can be mitigated by adopting and following industry best practices, norms, and expectations for firewall management, such as the National Institute of Standards and Technology (NIST) guidelines, the Center for Internet Security (CIS) benchmarks, or the Payment Card Industry Data Security Standard (PCI DSS) requirements . References = Risk and Information Systems Control Study Manual, Chapter 4, Section 4.2.1, page 115. What Is A Managed Security Service Provider (MSSP)? - Fortinet, What is a Firewall? - Definition from Techopedia, Firewall Administrator Job Description - Betterteam, What is a Firewall Log? - Definition from Techopedia, Firewall Log Management: Why It's Important and How to Do It Right, How to Write a Service Level Agreement (SLA) for an MSSP, [Firewall Auditing: Best Practices for Security and Compliance], [Guidelines on Firewalls and Firewall Policy | CSRC], [CIS Firewall Benchmark - CIS], [PCI DSS and Firewalls - PCI Security Standards Council]

The risk treatment response that should be reflected in the risk register when an IT department decides to keep the data center in-house instead of outsourcing it to an overseas location is risk avoidance. Risk avoidance is a risk response strategy that involves eliminating the source of the risk, or changing the plan or scope of the activity, to avoid the risk altogether. Risk avoidance can help to reduce the risk exposure and impact to zero, by removing the possibility of the risk occurrence. In this case, the IT department avoids the risk of outsourcing the data center to an overseas location, which could involve various threats, vulnerabilities, and uncertainties, such as data security, legal compliance, service quality, communication, or cultural issues. By keeping the data center in-house, the IT department maintains the control and ownership of the data center, and eliminates the potential risk associated with the outsourcing. Risk mitigation, risk acceptance, and risk transfer are not the correct risk treatment responses, as they do not reflect the actual decision and action taken by the IT department, and they do not eliminate the risk source or occurrence. References = CRISC Review Manual, 6th Edition, ISACA, 2015, page 51.

The first step to reduce the likelihood of infection from the attack is to identify systems that are vulnerable to being exploited by the attack. This would help the organization to assess the scope and severity of the risk, and to prioritize the systems that need immediate protection. Identifying systems that are vulnerable to being exploited by the attack would also help the organization to apply the appropriate patches, updates, or configurations to prevent or mitigate the attack, and to isolate or disconnect the systems that are already infected or compromised. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 2, Section 2.1.2, page 60123

Accepting residual risk is the most important responsibility of a risk owner, as it implies that the risk owner is accountable for the risk and its impact on the enterprise's objectives and operations. Residual risk is the risk that remains after the implementation of controls, and it should be aligned with the risk appetite and tolerance of the enterprise. The risk owner is responsible for implementing the risk response strategies and monitoring the risk status and outcomes, as well as for reporting and escalating the risk issues and incidents. Testing control design, establishing business information criteria, and establishing the risk register are not the most important responsibilities of a risk owner, but rather the tasks or activities that the risk owner may perform or delegate as part of the risk management process. References = CRISC Certified in Risk and Information Systems Control - Question218; ISACA Certified in Risk and Information Systems Control (CRISC) Certification Exam Question and Answers, question 218.