Cloud computing is becoming popular day-by-day as many enterprise applications and data are moving into cloud based platforms. With the increasing use and demand of cloud computing, security has become the major concern. Attack prevention measures such as authentication, encryption alone are not the solution for this; hence Intrusion Detection Systems have come into focus. The authors need a second wall of defense known as Intrusion Detection Systems (IDSs), to detect and produce responses if necessary. Since cloud computing is distributed in nature, supports multi-user and multi-domain platform, it is more prone to security threats.