rkt enter lacks isolation features about rkt HOT 2 OPEN

Consider the following scenario:

• An attacker who compromised a rkt pod wishes to compromise the host
• The attacker substitutes /bin/bash inside the container with a malicious binary
• A rkt user runs rkt enter ${pod-id} bash
• The malicious binary is executed inside the container, but without several necessary isolation features (seccomp, cgroups, all capabilities). Thus the malicious binary can break out of the container and the attacker can run arbitrary code on the host as root.

To break out of the container, the malicious binary can run the following commands:

stat / | grep "Device" | awk '{print $2}' # get the  minor and major numbers of the root fs device
mknod --mode 0600 /dev/host_root_fs_device b ${major-num} ${minor-num}
mkdir /host_root
mount  /dev/host_root_fs_device /host_root

See this POC video. For more details see this post.

from rkt.

I do not understand how this is a vulnerability. rkt enter is an interactive root-only command (requires sudo or root access). IMHO interactive root session started by admin (e.g. to enter container for inspection, etc.) should not be restricted.

from rkt.