Getting out of the box¶
A container is a process with opinions about what it can see. The boundary is a set of kernel features rather than a hypervisor, so leaving it means finding the feature that was relaxed: a capability left in, a socket mounted through, a path from the container’s filesystem to the host’s. Most escapes are configuration rather than exploitation, and the configuration was usually deliberate, because something legitimate needed it.
The walls are options, and somebody turned one off.