02/13/2019

High Severity RunC Vulnerability Exposes Docker And Kubernetes Hosts

The State of Security

Often claimed as a worst-case scenario, a container breakout vulnerability has been discovered in RunC, the universal container runtime used by Docker, Kubernetes and other containerization systems.

Further research has discovered that a similar version of the same vulnerability affects the LXC and Apache Mesos packages. Identified as CVE-2019-5736, this vulnerability grants root access to host systems running all of the most popular containerization technologies.

A container breakout occurs when a malicious Docker image or container exploits a vulnerability in order to achieve a level of access on the host system. While extremely rare, it has been years since a container breakout vulnerability has been disclosed in a core component of Docker – that streak has now ended.

This vulnerability allows a container to overwrite the RunC binary and gain root level code execution access with minimal user interaction.  This vulnerability can be exploited in the following ways:

• Creating a new container based on a malicious attacker controlled image
• Attaching to an existing container which an attacker had previous write access to

Since a large portion of containers are based on images created by third-parties, it is vital to patch systems immediately as most users will have exposure to images and containers created by unknown parties.

Read more...