Common Container Manager Is Vulnerable to Dangerous Exploit

A vulnerability in the way a common container management component spawns a service called a "shim" could allow unauthorized third parties to initiate containers with arbitrary contents and arbitrary permission levels.

The vulnerability, discovered by researchers at NCC Group, lies in the way containerd -- a core container runtime -- and specifically containerd-shim listen to Unix domain sockets for messages relating to the container it is managing. This container manager vulnerability is one of several weaknesses and vulnerabilities recently disclosed for Docker and other container management systems.

Typically, containerd-shim would listen and create the container using an abstract Unix domain socket. These abstract Unix domain sockets are tied to the Unix namespace rather than a particular file path. And that broader binding is the source of the trouble.

Because of the namespace tie, containerd-shim will expose APIs that can escape from the container and execute privileged commands on the host server. This is why the vulnerability has been given a CVCC of 8.8.

NCC Group provides a number of recommendations for making containerd safer, and notes that the newest versions of containerd have patched for this vulnerability. CVE-2020-15257. 

For more, read here.