Security is of paramount importance in cloud environments, particularly concerning scalability and elasticity. As organizations increasingly rely on cloud infrastructure to manage fluctuating workloads and dynamic demands, addressing security concerns is crucial to mitigate risks associated with unauthorized access, data breaches, and compliance violations. This paper explores the specific security requirements related to scalability and elasticity in cloud computing, examining the challenges, strategies, and best practices for maintaining a robust security posture during resource scaling and dynamic provisioning. This work discusses an adaptive security framework that integrates machine learning techniques, such as Isolation Forest, One-Class SVM, and RNNs—with the Zero Trust model to enhance protection in scalable infrastructures. For real-world threats like Yo-Yo attacks, this work introduces Trust-based Adversarial Scanner Delaying (TASD) to mitigate Yo-Yo attacks. The proposed approach provides a resilient and intelligent defense strategy tailored for modern, cloud-based systems.