If the intrusion causes the system processes to hang, the system availability has been affected. The system availability is the property or the characteristic of the system that ensures that the system is accessible and functional when needed by the authorized users or entities, and that the system is protected from the unauthorized or the malicious denial or disruption of service. The system availability can be affected when the system processes hang, as it can prevent or delay the system from responding to the requests or performing the tasks, and it can cause the system to crash or freeze. The system availability can also be affected by other factors, such as the network congestion, the hardware failure, the power outage, or the malicious attacks, such as the distributed denial-of-service (DDoS) attack. System integrity, system confidentiality, and system auditability are not the properties or the characteristics of the system that have been affected, if the intrusion causes the system processes to hang, as they are related to the accuracy, the secrecy, or the accountability of the system, not the accessibility or the functionality of the system. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 3, Security Architecture and Engineering, page 263. Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 3, Security Architecture and Engineering, page 279.