The Risks Associated with Containerized Environments
Containerized environments have transformed application deployment by providing isolated runtime environments that encapsulate dependencies and ensure consistency. However, this isolation is often overstated, as containers share the host system’s kernel, leading to security vulnerabilities. Insights gained from providing Compromise Assessments, SOC Consulting, and Incident Response services highlight that many organizations struggle with inadequate container visibility. Frequently, monitoring focuses more on operational health than on security threats. Misconfigurations in logging may hinder effective visibility, complicating the tasks of threat hunters and incident responders who face challenges distinguishing processes running within containers from those executing on the host.
Understanding Container Operation
To effectively manage security within these environments, it’s crucial to grasp how containers function. Unlike virtual machines, which run entirely separate operating systems, containers share a host’s OS kernel and utilize Linux features like namespaces and control groups (cgroups) for resource management. Consequently, every process in a container operates on the host while existing in a separate namespace. Threat hunters often depend on host execution logs for insights into executed processes, but incomplete logging configurations may lack essential attributes such as namespaces or specific system calls.
Container Creation Workflow
Users interact with tools like Docker CLI and kubectl to create and manage containers. These tools communicate with high-level container runtimes such as containerd and CRI-O, which in turn rely on low-level runtimes like runc for direct interaction with the Linux kernel. Each container is established based on a bundle that contains configurations and a root filesystem defined by the Open Container Initiative (OCI) Runtime Specification.
Runc operates in two modes: foreground and detached. In foreground mode, a long-running runc process remains in the foreground, facilitating standard input/output interaction. Conversely, in detached mode, runc exits immediately after creation, allowing the container process to be managed by a shim process rather than PID 1, which is usually the systemd process. This shim process is critical for maintaining container independence, log management, and process cleanup.
Threat Hunting in Containers
Despite traditional shell processes, such as BusyBox, enhancing lightweight containers, they can also serve as indicators of suspicious activity. For instance, deploying BusyBox-based shells in non-standard environments (like Debian or RedHat) warrants further investigation. Inside containers, all commands executed by BusyBox occur either directly within that process or as child processes, maintaining isolation while still sharing the host’s kernel.
Threat hunters must be vigilant as benign activities in a host’s environment can indicate malicious intent within a container. For instance, installing Docker CLI within a running container, while acceptable on host systems, can signal a breach. By tracking process execution chains and leveraging logging strategies, investigators can discern origins of anomalies and respond accordingly.
Investigation Value and Security Tools
Security tools, including Kaspersky Container Security and Auditd, facilitate monitoring container activities and capturing critical logs. However, predefined rules for these tools are often not tailored for containerized environments, complicating the differentiation between host and container activities.
During investigations, the detection of suspicious commands or the presence of unusual binaries necessitates a comprehensive approach to process tracking. For instance, identifying a Docker container creation event can expose potentially malicious activities showcasing unusual command-line arguments. Monitoring these behaviors enhances threat detection capabilities, allowing teams to identify compromised containers promptly.
Conclusion
While containerized environments are integral to modern networks due to their operational efficiencies, they inherently possess risks that security teams often overlook. Misunderstandings about container isolation lead to vulnerabilities that can be exploited. Employing comprehensive monitoring solutions and following meticulous investigative procedures are essential for threat detection and mitigation. By understanding container architectures and leveraging effective logging practices, organizations can better navigate the complexities of security in containerized ecosystems.