  Currently, different forms of ransomware are increasingly threatening
Internet users. Modern ransomware encrypts important user data and it is only
possible to recover it once a ransom has been paid. In this paper we show how
Software-Defined Networking (SDN) can be utilized to improve ransomware
mitigation. In more detail, we analyze the behavior of popular ransomware -
CryptoWall - and, based on this knowledge, we propose two real-time mitigation
methods. Then we designed the SDN-based system, implemented using OpenFlow,
which facilitates a timely reaction to this threat, and is a crucial factor in
the case of crypto ransomware. What is important is that such a design does not
significantly affect overall network performance. Experimental results confirm
that the proposed approach is feasible and efficient.
