3.6 KiB
Docker Forensics
Container modification
There are suspicions that some docker container was compromised:
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
cc03e43a052a lamp-wordpress "./run.sh" 2 minutes ago Up 2 minutes 80/tcp wordpress
You can easily find the modifications done to this container respecting to the image with:
docker diff wordpress
C /var
C /var/lib
C /var/lib/mysql
A /var/lib/mysql/ib_logfile0
A /var/lib/mysql/ib_logfile1
A /var/lib/mysql/ibdata1
A /var/lib/mysql/mysql
A /var/lib/mysql/mysql/time_zone_leap_second.MYI
A /var/lib/mysql/mysql/general_log.CSV
...
In the previous command **C **means **Changed **and A, Added.
If you find that some interesting file like /etc/shadow was modified you can download it from the container to check for malicious activity with:
docker cp wordpress:/etc/shadow .
You can also compare it with the original one running a new container and extracting the file from it:
docker run -d lamp-wordpress
docker cp b5d53e8b468e:/etc/shadow original_shadow #Get the file from the newly created container
diff original_shadow shadow
If you find that some suspicious file was added you can access the container and check it:
docker exec -it wordpress bash
Images modifications
When you are given an exported docker image (probably in .tar format) you can use container-diff to extract a summary of the modifications:
docker save <image> > image.tar #Export the image to a .tar file
container-diff analyze -t sizelayer image.tar
container-diff analyze -t history image.tar
container-diff analyze -t metadata image.tar
Then, you can **decompress **the image and access the blobs to search for suspicious files you may have found in the changes history:
tar -xf image.tar
In order to find added/modified files in docker images you can also use the dive** **(download it from releases) utility:
#First you need to load the image in your docker repo
sudo docker load < image.tar 1 ⨯
Loaded image: flask:latest
#And then open it with dive:
sudo dive flask:latest
This allow you to navigate through the different blobs of docker images and check which files were modified/added. **Red **means added and **yellow **means modified. Use **tab **to move to the other view and **space **to to collapse/open folders.
With die you won't be able to access the content of the different stages of the image. To do so you will need to decompress each layer and access it.
You can decompress all the layers from an image from the directory where the image was decompressed executing:
tar -xf image.tar
for d in `find * -maxdepth 0 -type d`; do cd $d; tar -xf ./layer.tar; cd ..; done
Credentials from memory
Note that when you run a docker container inside a host you can see the processes running on the container from the host just running ps -ef
Therefore (as root) you can dump the memory of the processes from the host and search for **credentials **just like in the following example.