docker container root user

This user will need to be created manually, and any required files should be chown-d to match this user. That way your container is run in a (more) secure way. Whether a quick hack, or just a PoC that you want to get running - sometimes you do want to install into a container, and that can be more difficult without root. This means the entry point script is still run as root, but in much the same way applications like nginx change user, this isnt for very long. root is needed to configure certain container aspects needed to function correctly. A container is just a single process. So its logical that Docker security is an important subject. The image will run and it will prepare environment for the node app. The server gets the data and attacker can use this data for his evil purposes. It gives the ability to specify a uid that is the owner of a Docker container process. Unlock the hidden potential of data to drive tangible business results. By default, Docker containers run as root. For applications like this, changing the user is probably not what you want, and should be handled in the application configuration itself. We promise that you wont see any ads on our site! We went through kernel guid and uid mechanisms and how it maps between Docker container and kernel. So he has full privileges. On the kernel level, only the uid/gid matter. You can check what user your container is running with: Using the --user root argument when launching the Docker exec command you can override the containers user: Now, installing into Docker containers is not The Right Way - you should amend the Docker image to install whats needed before invocation as a container. So when you run a docker process, it gets the privileges of the root. The / from the host was mounted in the Docker container as /home/notImportantDir/ directory. Most base images have the current user set to root because theyre used as a base to build on and install needed packages, for which root privileges are often needed. Ill illustrate this with an example of user used in a Dockerfile. The output of this file is then stored in the stolenEnv.txt file by the cmd.sh script. The root user of that host machine is making the best avocado toast ever and youd like to know her secret which she stored in /home/vlatka/recipes/secret_ingredient.txt file. In this case, the docker process that runs as root. After having appended those lines to the existing Dockerfile, we build the image, run its container in the same way as before and try to access the avocado toast secret: As we can see, the new container is running with toto_user and that user cant read the root-owned files from the host machine. This script iterates through all the processes and it prints all the environment variables. An introduction to multithreading in the browser. Raise an issue! This is the same command as the one that we used when we ran the container in the first example. Neoteric sp. #self-hosting. To sum up, always change the user from root to a non-privileged user in your Dockerfile when you no longer need root privileges. In this article, well look under the hood of Docker container privileges. #containers Its concept of containerization has made it easy to set up, share and deploy software projects. This is the file that is the most important. Some applications, like nginx, already handle changing user as part of normal operation. Most commercial container hosting offerings just run your containers in VMs, to massively reduce inter-client security issues. Tech companies care about the security of their data and applications. That can be done with two simple instructions which create a user in the container and set it as the current user. As you are root now, you can access root-owned files and finally get the avocado toast secret: And to be able to run sudo without a password, you do: When you exit the container, you can do all the damage you want to the host machine because you have the root privilege even though youre not root. We build the image with Dockerfile from the current directory and we specify a friendly name with the -t option. That root user is the same root user of the host machine, with UID 0. But, when inside a container, which user does the process run as. Another lesson we can draw from this is that we should avoid adding users to docker user group unless we really trust them. dockerd (the docker daemon) runs as root, and this is normal. With this, an attacker can not only mess with the application, but potentially install additional tools to help pivot to other devices or containers. Inside the container, the user is root, and so can do whatever they want in the container. Googled, found the the --user flag for Docker, tried that: Evidently, the Docker image tries to change directory to the Oracle home folder which Dockers not happy doing as another user (even though its root?). When root executes this command, that is the point when things can get really bad. For details on how this impacts security in your system, see Docker Daemon Attack Surface. This strategy works very well as itll make sure the application file permissions match the process user, so applications will always have access to their files. An alternative approach is to change user at startup. P.S. Now the fun part. https://docs.docker.com/engine/security/security/, Backing up and restoring Docker containers. Well a lot of things. Lets prepare some docker image for this scenario. He likes writing about himself in the third person, eating good breakfasts, and drinking good beer. Not all containers will just deal with it. z o.o. Here is the Dockerfile with environment for node app and with some bash commands to execute. JobTeaser's Engineering Team sharing tips and thoughts about programming, software engineer @ Swile && food blogger @ cuisinehacker.herokuapp.com, Creating AWS Lambda Layer with Terraform in 3min, Linux Hard Disk Format Partitions / fdisk, DATABASE MANAGEMENT SYSTEMINTRODUCTION: 2, Model-Driven to Domain-Driven Lets take a look, Visual Studio Code 101 #8: 10+ Docker and kubernetes container extension in recommendation, Creating a Lightweight Local Windows K8S & Docker Development Environment, Jenkins multibranch pipeline scan logs throwing git exception errorPossible scenarios, Use Jenkins to Automate Project Versioning, docker run -v /:/host -it avocado_secret_theft, echo "vlatka ALL=(ALL) NOPASSWD: ALL" > /host/etc/sudoers.d/toto, a lot of Dockerfiles contain vulnerabilities, they can copy sensitive files from the host to the container and access them, if some sensitive root-owned file is mounted to the container, they can access it from the container as theyre root. However, a lot of Dockerfiles contain vulnerabilities. Going forward, when we run docker, it requires root privileges. Its not a good idea to have containers running as root, for the same reasons its not a good idea to run all your processes as root. Whether that be a web server like Nginx, database like PostgreSQL or an init system like s6 to spawn and handle even more processes. There was a little bit about user privileges and how to force the container to run as a specific user. Unlike VMs, containers run closer to the host operating system, so close they use the same kernel, meaning its even more important to protect it. LinuxServer.io, the makers of a bunch of high-quality containers, use the $PUID and $PGID environment variables to configure the user and group of the process and related files. As a result, the docker container process grants root privileges. The great part of the Docker is that it is lightweight, but what does it entail? Googled some more, found the --workdir flag to override the WORKDIR setting of the Dockerfile from which the image is built: Robin Moffatt is a Principal Developer Advocate at Confluent, and an Oracle ACE Director (Alumnus). The Docker container does not have its own kernel. Lets see how you can do this with the help of Docker. 13 Node.js safety enhancing practices, How to start working with Protractor and run your first E2E test, A start-smart guide to successful AI adoption, Dos and donts of building online fitness applications, Data science, machine learning, and AI in fitness now and next. Many containers, if configured incorrectly, will stop functioning entirely if you try to change the user without them expecting it. Keep the above examples in the back of your head when you run any Docker image. This fact can enable hackers to perform various types of attacks on your app if they get hold of your vulnerable container: Imagine that you have access a machine that has Docker installed and your current user is a non-root user named vlatka that belongs to the docker group. How to make your web app mobile with Cordova, 50+ successful products for clients from 5 continents. See a container which runs as root? When async is just not enough. There are good reasons why running in a container as root is not a good idea, and thats why many images published nowadays avoid doing this. As a container maintainer, the USER keyword in the Dockerfile sets the running user. Learn from the industry leaders and experts, Join the discussions, enjoy the networking. The -v flag gives us the ability to mount a volume, so we mount / volume from the host and we specify that it will be available at /home/notImportantDir/. | VAT-ID: PL 957-107-23-74 | Marynarki Polskiej 163, 80-868 Gdask, Poland. To do that, here are some articles I found useful: Also, I suggest using a linter like Hadolint that can warn you before merging new unsafe Docker code. Once in the container, by doing ls you can see that you have the whole host file system in the host directory. It relies on the host kernel, so the user inside of the docker container with uuid=0 is the same user on the host system with uuid=0. This file executes the readEnv.sh script and puts the output in stolenEnv.txt, then executes the node app. By default, containers are run as root. Please feel free to share and lets discuss it! during the writing of this article, twelve ubuntu VMs were harmed. Docker is quite a viral technology. Basically, the command removes everything from the / directory on host system. I hope this example illustrates how important it is to get acquainted with the Docker best practices. This argument takes the user id of the user to change the process to. All rights reserved. There may be ways of running without root, but its fine as it is. Note that this doesnt change anything else about the container. What can possibly go wrong? If theres a vulnerability in the application, then an attacker can gain root access into the container. Just because the process is in a container, doesnt mean its completely protected, nor that these reasons dont apply. An introduction to multithreading in the browser, Is Node safe? If theres a vulnerability in docker, or the kernel itself, allowing a process inside the container to break out, then they now have a process running on your host as root. 2020-08-18 4 minutes Such Dockerfile creates an image that will be run as a basic user. When we install the docker, we go through docker post-install. The docker process runs the docker container process. Selenium IDE Integrated Development Environment is a Firefox plugin which makes testers life easier. Is Node.js safe? access to additional resources) may not be available. Bare with me as we go through some of the dark scenarios of malicious Docker images. There are so many reasons not to run all your processes as root. Over the past few years, Docker has become a quintessential technology used in software development. Protractor is a E2E testing framework that runs tests by sending requests to the Webdriver via Selenium Server. Moreover, well tackle the uid and gid mechanism in linux kernel. This node app reads the stolenEnv.txt file and makes a post request with the environment variables to http://theaftDomain.com/stolen-env. VMs are a much better understood technology, and have a lot more isolation. Yes, the user with uuid=0 is a root. Unfortunately, your ad blocker blocks more than the ads so if you dont turn it off, some functions of the site (e.g. A significant part of the IT world relies on Docker containers as they are easy to use and portable. As we have root access we can think of stealing some confidential data. It means that the container will not have root privileges and wont be able to do any harm to the host system. at https://rmoff.net/2021/01/13/running-as-root-on-docker-images-that-dont-use-root/, the Dockerfile from which the image is built. Therefore its used by a lot of tech companies (to name a few: PayPal, Uber, Spotify, VISA). Some containers still run as root, but perhaps this is for good reason (or theyre not fussed). Docker containers, and containers as a whole, are really just a regular program wrapped in some extra protections provided by the kernel (namely cgroups etc) to create isolation, and other interesting features. Confluent Platforms Docker images changed to using appuser with the 6.0 release. Lets run this very innocent docker image and give the container / directory as volume. A lot of them are written without keeping the best practices in mind. There is a little warning there: The docker group grants privileges equivalent to the root user. Also, youd like to have root privileges on the host, by not having to type the password when running sudo. Docker itself supports changing the user using the --user argument (or user key in docker-compose.yml). But the result will differ now it will not erase all system files as the container does not have privileges of root. AI in business: What are the benefits of artificial intelligence? The Docker container with every run creates a new group with gid=1000 and adds the user with uid=1000 to this group. The best solution is to use the user option. When a user wants to perform some action on a file, the kernel checks if the uid has enough privileges to proceed. In this article, we walked through some of the malicious Docker images examples. For example, we can steal some environment variables (env) of processes. Whats the difference between quality assurance and testing in the software industry? Nginx requires root access to bind to port 80, but the processes handling user requests or executing further scripts (PHP etc) is configured inside nginx itself. Of course, a lot more can be done to secure your Docker containers, so wed be happy to learn some of your go-to techniques. You can use the same approach as above (--user root): Using Oracles Docker database image I wanted to install some additional apps, without modifying the Dockerfile. A basic user can execute this command, but it will not harm the system, as he has no rights to delete core files of the system. Using the user option, you have to remember that it will override the user specified in Dockerfile. #docker The username is assigned to a specific uid thanks to external tools. Node.js is executing the "JavaScript everywhere" doctrine. On the machine there are some Dockerfiles, namely one that is used for a Python project: You build it as an image called avocado_secret_theft: Then you mount the whole root filesystem of your host machine to the avocado_secret_theft container and run it in interactive mode. #security z o.o. The first one is when we run a docker image from an untrusted source. 2022. Neoteric sp. That process inherits the privileges form the parent process. The second case is when we want to build an image and want the container to run with ordinary users permissions. Read also: When async is just not enough. We can think of two cases. The Docker container executes the rm -rf /home/notImportantDir command inside of the container. You can more about container security at https://docs.docker.com/engine/security/security/. Changing the user running prevents the previous issues. And that presents a serious threat to the security of the app thats using Docker. Create web applications that will support your business goals. Game Over. Yep, long story short, you got no system. We want to use the debian:stretch base image, and then execute therm -rf /home/notImportantDir command. BUT sometimes needs must. However, it is up to the creator of the Dockerfile to override that root user when its no longer needed so that the container is run with a less-privileged user. Design digital products that support your business goals. It is a standard approach to keep confidential data like API keys, app settings or secret passphrases in env, so it can be a precious piece of data for the attacker. As a container user, youre at the mercy of the container maintainers as to the quality of the support for changing user. Wait What? We will consider some scenarios of malicious Docker images and how to protect your host machine from that. Its crucial to understand that kernel does not recognize usernames. Tools like s6-overlay make this very easy to manage (this is the same tool LSIO use). Best AI and ML Company in 2021 according to. Oops, something went wrong?

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