According to Aleksa Sarai, a SUSE container senior software engineer and a runC maintainer, security researchers Adam Iwaniuk and Borys Popawski discovered a vulnerability, which “allows a malicious container to (with minimal user interaction) overwrite the host runc binary and thus gain root-level code execution on the host. The level of user interaction is being able to run any command (it doesn’t matter if the command is not attacker-controlled) as root.” To do this, an attacker has to place a malicious container within your system. But, this is not that difficult. Lazy sysadmins often use the first container that comes to hand without checking to see if the software within that container is what it purports to be.Red Hat technical product manager for containers, Scott McCarty, warned: “The disclosure of a security flaw (CVE-2019-5736) in runc and docker illustrates a bad scenario for many IT administrators, managers, and CxOs. Containers represent a move back toward shared systems where applications from many different users all run on the same Linux host. Exploiting this vulnerability means that malicious code could potentially break containment, impacting not just a single container, but the entire container host, ultimately compromising the hundreds-to-thousands of other containers running on it. While there are very few incidents that could qualify as a doomsday scenario for enterprise IT, a cascading set of exploits affecting a wide range of interconnected production systems qualifies…and that’s exactly what this vulnerability represents.”
An anonymous reader quotes a report from ZDNet: One of the great security fears about containers is that an attacker could infect a container with a malicious program, which could escape and attack the host system. Well, we now have a security hole that could be used by such an attack: RunC container breakout, CVE-2019-5736. RunC is the underlying container runtime for Docker, Kubernetes, and other container-dependent programs. It’s an open-source command-line tool for spawning and running containers. Docker originally created it. Today, it’s an Open Container Initiative (OCI) specification. It’s widely used. Chance are, if you’re using containers, you’re running them on runC.