Explanation: The type of attack that embedded systems may be prone to without proper signal protection is information disclosure. Information disclosure is a type of attack that exposes or reveals sensitive or confidential information to unauthorized parties, such as attackers, competitors, or the public. Information disclosure can occur through various means, such as interception, leakage, or theft of the information. Embedded systems are systems that are integrated into other devices or machines, such as cars, medical devices, or industrial controllers, and perform specific functions or tasks. Embedded systems may communicate with other systems or devices through signals, such as radio frequency, infrared, or sound waves. Without proper signal protection, such as encryption, authentication, or shielding, embedded systems may be vulnerable to information disclosure, as the signals may be captured, analyzed, or modified by attackers, and the information contained in the signals may be compromised. Brute force, tampering, and denial of service are not the types of attack that embedded systems may be prone to without proper signal protection, as they are related to the guessing, alteration, or prevention of the access or functionality of the systems, not the exposure or revelation of the information. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 3, Security Architecture and Engineering, page 311. Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 3, Security Architecture and Engineering, page 327.