Many organizations and service providers have started shifting from traditional server-cluster infrastructure to cloud-based infrastructure. The threat of Distributed Denial of Service (DDoS) attack continues to wreak havoc in these cloud infrastructures. In addition to DDoS attacks, a new form of attack known as Economic Denial of Sustainability (EDoS) attack has emerged in recent years. EDoS which is unique to cloud infrastructure may not be easily detected as with DDoS. Although EDoS attack is small at the moment, it is expected to grow in the near future in tandem with the growth in cloud usage. As EDoS has a major impact economically, it can considered to be more serious than DDoS and many defence and mitigation mechanisms have been proposed to combat these attacks. This paper introduces EDoS and how it differs from DDoS. The existing mitigation techniques are described and the drawbacks of these techniques are explained.

Abstract-Cloud computing (CC) is the next revolution in the Information and Communication Technology arena. CC is oftenprovided as a service comparable to utility services such as electricity, water, and telecommunications. Cloud service providers (CSP) offers tailored CC services which are delivered as subscription-based services, in which customers pay based on the usage. Many organizations and service providers have started shifting from traditional server-cluster infrastructure to cloudbased infrastructure. Nevertheless, security is one of the main factors that inhibit the proliferation of cloud computing. The threat of Distributed Denial of Service (DDoS) attack continues to wreak havoc in these cloud infrastructures. In addition to DDoS attacks, a new form of attack known as Economic Denial of Sustainability (EDoS) attack has emerged in recent years. DDoS attack in conventional computing setup usually disrupts the service, which affects the client reputation, and results in financial loss. In CC environment, service disruption is very rare due to the auto-scalability (Elasticity), capability, and availability of service level agreements (SLA). However, auto scalability utilize more computing resources in event of a DDoS attack, exceeding the economic bounds for service delivery, thereby triggering EDoS for the organization targeted. Although EDoS attacks are small at the moment, it is expected to grow in the near future in tandem with the growth in cloud usage. There are few EDoS detection and mitigation techniques available but they have weaknesses and are not efficient in mitigating EDoS. Hence, an enhanced EDoS mitigation mechanism (EDoS-EMM) has been proposed. The aim of this mechanism is to provide a realtime detection and effective mitigation of EDoS attack.