hacktricks/forensics/basic-forensic-methodology/docker-forensics.md

# Docker Forensics

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## Container modification

There are suspicions that some docker container was compromised:

```bash
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:

```bash
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:

```bash
docker cp wordpress:/etc/shadow .
```

You can also **compare it with the original one** running a new container and extracting the file from it:

```bash
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:

```bash
docker exec -it wordpress bash
```

## Images modifications

When you are given an exported docker image (probably in `.tar` format) you can use [**container-diff**](https://github.com/GoogleContainerTools/container-diff/releases) to **extract a summary of the modifications**:

```bash
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:

```bash
tar -xf image.tar
```

### Basic Analysis

You can get **basic information** from the image running:

```bash
docker inspect <image> 
```

You can also get a summary **history of changes** with:

```bash
docker history --no-trunc <image>
```

You can also generate a **dockerfile from an image** with:

```bash
alias dfimage="docker run -v /var/run/docker.sock:/var/run/docker.sock --rm alpine/dfimage"
dfimage -sV=1.36 madhuakula/k8s-goat-hidden-in-layers>
```

### Dive

In order to find added/modified files in docker images you can also use the [**dive**](https://github.com/wagoodman/dive) (download it from [**releases**](https://github.com/wagoodman/dive/releases/tag/v0.10.0)) utility:

```bash
#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:

```bash
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**](../../linux-hardening/privilege-escalation/#process-memory).

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