README.md

Docker Explorer

This project helps a forensics analyst explore offline Docker filesystems.

Overview

When analyzing a system where a Docker container has been compromised, it can be useful to have the same view of the filesystem as the container's.

Docker uses layered backend filesystems like AuFS or OverlayFS.

Each layer is actually stored on the host's filesystem as multiple folders, and some JSON files are used by Docker to know what is what;

Usage

For the forensicator, this usually goes:

1. find the interesting container ID
2. mount the container's filesystem in /mnt/aufs
3. log2timeline.py /tmp/container.plaso /mnt/aufs

List the running containers

On the live host:

# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED         STATUS              PORTS               NAMES
7b02fb3e8a66        busybox             "sleep 10d"         19 hours ago    Up 19 hours                             dreamy_snyder

On a disk image mounted in /mnt/root:

# de.py -r /mnt/root/var/lib/docker list running_containers
Container id: 7b02fb3e8a665a63e32b909af5babb7d6ba0b64e10003b2d9534c7d5f2af8966 / Labels :
    Start date: 2017-02-13T16:45:05.785658046Z
    Image ID: 7968321274dc6b6171697c33df7815310468e694ac5be0ec03ff053bb135e768
    Image Name: busybox

Mount the container's filesystem:

On the live host:

# find ID of your running container:
docker ps

# create image (snapshot) from container filesystem
docker commit 12345678904b5 mysnapshot

# explore this filesystem using bash (for example)
docker run -t -i mysnapshot /bin/bash

On a disk image mounted in /mnt/root:

# de.py -r /tmp/ mount 7b02fb3e8a665a63e32b909af5babb7d6ba0b64e10003b2d9534c7d5f2af8966 /tmp
You'll needs the aufs-tools package. If you install aufs-tools, I can run these for you.

Whoops... Let's try again

# apt-get install aufs-tools
# de.py -r /tmp/ mount 7b02fb3e8a665a63e32b909af5babb7d6ba0b64e10003b2d9534c7d5f2af8966 /tmp/test
mount -t aufs -o ro,br=/tmp/docker/aufs/diff/b16a494082bba0091e572b58ff80af1b7b5d28737a3eedbe01e73cd7f4e01d23=ro+wh none /tmp/test
mount -t aufs -o ro,remount,append:/tmp/docker/aufs/diff/b16a494082bba0091e572b58ff80af1b7b5d28737a3eedbe01e73cd7f4e01d23-init=ro+wh none /tmp/test
mount -t aufs -o ro,remount,append:/tmp/docker/aufs/diff/d1c54c46d331de21587a16397e8bd95bdbb1015e1a04797c76de128107da83ae=ro+wh none /tmp/test
Do you want to mount this container Id: /tmp/docker/aufs/diff/b16a494082bba0091e572b58ff80af1b7b5d28737a3eedbe01e73cd7f4e01d23 on /tmp/test?
      (ie: run these commands) [Y/n]

root@test-VirtualBox:~# ls /tmp/test
bin  dev  etc  home  proc  root  sys  tmp  usr  var

List the available images

On the live host:

# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED       SIZE
busybox             latest              7968321274dc        4 weeks ago   1.11 MB

On a disk image mounted in /mnt/root:

# de.py -r /mnt/root/var/lib/docker list repositories
Listing repositories from file /tmp/docker/image/aufs/repositories.json
{
    "Repositories": {
        "busybox": {
            "busybox:latest": "sha256:7968321274dc6b6171697c33df7815310468e694ac5be0ec03ff053bb135e768"
        }
    }
}

Show a container's image history

On the live host:

# docker history 7968321274dc6b6171697c33df7815310468e694ac5be0ec03ff053bb135e768
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
7968321274dc        4 weeks ago         /bin/sh -c #(nop)  CMD ["sh"]                   0 B
<missing>           4 weeks ago         /bin/sh -c #(nop) ADD file:707e63805c0be1a226   1.11 MB

On a disk image mounted in /mnt/root:

# de.py -r /mnt/root/var/lib/docker history 7b02fb3e8a665a63e32b909af5babb7d6ba0b64e10003b2d9534c7d5f2af8966
--------------------------------------------------------------
sha256:7968321274dc6b6171697c33df7815310468e694ac5be0ec03ff053bb135e768
        size : 0
        created at : 2017/01/13 22:13:54
        with command : /bin/sh \
-c \
#(nop)  \
CMD ["sh"]

Troubleshooting

If on your Ubuntu system you get the errors:

mount: unknown filesystem type 'aufs'
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
/sbin/mount.aufs:proc_mnt.c:96: /mnt/aufs: Invalid argument
....

Try this:

sudo apt-get install linux-image-extra-$(uname -r)