  Distributed Denial of Service (DDoS) attacks are serious cyber attacks and
mitigating DDoS attacks in cloud is a topic of ongoing research interest which
remains a major security challenge. Fog computing is an extension of cloud
computing which has been used to secure cloud. Moving Target Defense (MTD) is a
newly recognized, proactive security defense that can be used to mitigate DDoS
attacks on cloud. MTD intends to make a system dynamic in nature and uncertain
by changing attack surface continuously to confuse attackers. In this paper, a
novel DDoS mitigation framework is presented to support Cloud-Fog Platform
using MTD technique (CFPM). CFPM applies migration MTD technique at fog layer
to mitigate DDoS attacks in cloud. It detects attacker among all the legitimate
clients proactively at the fog layer and isolate it from innocent clients. CFPM
uses an effective request handling procedure for load balancing and attacker
isolation procedure which aims to minimize disruption to cloud server as well
as serving fog servers. In addition, effectiveness of CFPM is evaluated by
analyzing the behavior of the system before and after attack, considering
different possible scenarios. This approach is effective as it uses the
advantage of both MTD technique and Fog computing paradigm supporting cloud
environment.
