Virtual Machines (VM) are very commonly used resources in a cloud environment. However, due to Distributed Denial of Service attacks, VM's became more vulnerable and its performance gets degraded. Hence, there is an inherent need for improving the security mechanism to detect and prevent the DDoS attacks in a VM. The crux for such mechanism is about guaranteeing that fast and early detection with minimal false alarm rate and ensures that the legitimate requests are not affected. At this end, a secure framework which includes cryptographic hash functions such as MD5 and SHA256 which are suggested and used in this work to create unique hash keys for each and every cloudlet (client request) into the virtual machines to identify illegitimate users in a VM. This work also conducts experimental comparisons on the computational overheads and it is proven that SHA-256 is more secure when compared to MD5. The obtained results show that the robustness and significance of the model towards mitigating the DDoS attacks in a virtual environment with maximum accuracy. © 2019-IOS Press and the authors. All rights reserved.