The surging popularity of Docker technology is primarily due to the fact that Docker Inc., in collaboration with other interested parties, has introduced an open and industry-strength image format for efficiently packaging, distribution, and running of software applications. However, stuffing many applications into a system opens up definite worries and vulnerabilities:

• Exploiting host kernels: Containers share the same host kernel and this sharing may turn out to be a single point of failure for the containerization paradigm. A flaw in the host kernel could allow a process within a container to break out to bring down the host machine. Thus the domain of Docker security is about exploring various options toward limiting and controlling the attack surface on the kernel. Security administrators and architects have to meticulously leverage the security features of the host operating system to secure the kernel.
• Denial-of-service (DoS) attacks: All containers ought to share kernel resources. If one container can monopolize access to certain resources including memory and processing, other containers on the host are bound to starve for computing, storage, and networking resources. Ultimately, the enigma of DoS creeps in and legitimate users would struggle for accessing the services.
• Container breakouts: An attacker who gains access to a container should not be able to gain access to other containers or the host. By default, users are not namespaced and hence any process that breaks out of the container will have the same privileges on the host as it has in the container. That is, if a process has the root privilege, then it has the root privilege on the host machine also. This means that a user can gain the elevated and even root privileges through a bug in an application code. Then the result is simply irreparable damages. That is, we need to adhere to the least privilege: each process and container should run with the minimum set of access rights and resources.
• Poisoned images: Docker images also can be compromised and tampered resulting in bad containers and hosts. We wrote about the methods for thoroughly cleansing and curating Docker images while depositing in image repositories. Similarly, strong access control mechanisms are in place for mitigating the poisoning of images.

Thus, Docker images, containers, clusters, hosts, and clouds are bound to be impeded with a litany of viruses, malware, and other crucial threats. Thus, the domain of Docker security has become the most challenging area for both researchers and practitioners lately and we can expect a number of game-changing and security-enhancing algorithms, approaches, and articulations in the days ahead.