In cloud computing resources like software and hardware are shared among multiple users by creating multiple instances of virtual machines (VMs). System cache is one of resource which is shared by Virtual machines in cloud environment. Such Virtual machines are targeted for abnormal activity like side channel attacks. Cache based side channel attack is one of the side channel attacks on cloud environments which leaks the private information of the client. The proposed approach includes the detection and prevention of cache based side channel attack in cloud infrastructure. The approach is based on two components: virtual machine status collection in the form of log files and use of fuzzy logic to detect and prevent the cache attack. Fuzzy logic defines set of fuzzy rules to identify the cache attack from the log file. The proposed approach could attain a maximum of 78.15%, 80.04%, and 82.16% of accuracy at 10, 20 and 30 sec. of time intervals.