The Distributed Denial-of-service (DDoS) attack is considered one of the largest threats to the availability of cloud computing services which is used to deny access for legitimate users of an online service. But, Economic Denial of Sustainability (EDoS) attack is a special breed of DDoS attack that targets cloud’s pay-as-you-go model. EDoS attack exploits auto scaling feature of cloud. The attacker generates malicious HTTP requests for web application. The Cloud Service Provider (CSP) scales the architecture automatically to service those requests for which cloud consumer is charged. This causes a sustainable decline in the economy of the consumer. The malicious HTTP traffic mimics to be legitimate and hence go undetected. As EDoS attack is carried over extended period of time, the security mechanisms against DDoS attack are not applicable to overcome EDoS attack. This paper presents an overview of detection and mitigation methodologies implemented so far against EDoS attack and it also points out research challenges in this field.