  The integration of Voice Control Systems (VCS) into smart devices and their
growing presence in daily life accentuate the importance of their security.
Current research has uncovered numerous vulnerabilities in VCS, presenting
significant risks to user privacy and security. However, a cohesive and
systematic examination of these vulnerabilities and the corresponding solutions
is still absent. This lack of comprehensive analysis presents a challenge for
VCS designers in fully understanding and mitigating the security issues within
these systems.
  Addressing this gap, our study introduces a hierarchical model structure for
VCS, providing a novel lens for categorizing and analyzing existing literature
in a systematic manner. We classify attacks based on their technical principles
and thoroughly evaluate various attributes, such as their methods, targets,
vectors, and behaviors. Furthermore, we consolidate and assess the defense
mechanisms proposed in current research, offering actionable recommendations
for enhancing VCS security. Our work makes a significant contribution by
simplifying the complexity inherent in VCS security, aiding designers in
effectively identifying and countering potential threats, and setting a
foundation for future advancements in VCS security research.
