escape character in dockerfile

Stevensons The Strange Case of Dr. Jekyll and Mr. Hyde are taken from Project Gutenbergs eBook, at: https://www.gutenberg.org/files/43/43-h/43-h.htm This is because ls detects that its output is going into a pipe rather than to a terminal display. Every time I Introduction This post describes the work weve done on fuzzing the Windows RDP client and server, the challenges of doing so, and some of the results. PS C:\John> docker build -t cmd . Step 2/2 : COPY testfile.txt c:\RUN dir c: The behavior with single quotes around the value in docker compose V1 is actually platform-dependent: If anything changes with respect to quotes or other escape character processing when reading .env files in compose V2, then this needs to be announced loudly (and correctly) in the migration docs. Things are fine and straightforward so far. Be We hear about it all the time data breaches that expose a companys sensitive information. Snap has a built-in integration with systemd, allowing packages containing daemons to register themselves as systemd units. The value provided in HTTP_PROXY is used by docker daemon process and it expects it to be URL encoded. So clearly the value was being picked up but was being considered invalid and ignored. Could one house of Congress completely shut down the other house by passing large amounts of frivolous bills? By default, snaps refresh to the latest version every four hours, so it is most likely that your system is already running the fixed version. When such a snap package is installed, the snap daemon (snapd) generates a systemd unit file (the systemd configuration file) on behalf of the packages daemon. Delegated cgroups themselves are managed by systemd, but programs are free to create sub-cgroups inside it without systemd interfering with them, as written in the systemd website: systemd wont fiddle with your sub-tree of the cgroup tree anymore. Sign in This process checks to see if there are any mandatory upgrades to download and apply. Stevensons The Strange Case of Dr. Jekyll and Mr. Hyde are taken from Project Gutenbergs eBook, at: https://www.gutenberg.org/files/43/43-h/43-h.htm Although cgroups are described as implementing resource accounting and limiting, the Devices cgroup, also called the Device Whitelist Controller in the kernel cgroups documentation [vii], seems to belong to a different breed. It aims to unify service configuration across different Linux setups and is widely adopted by the majority of Linux distributions. rev2022.8.2.42721. There is a lot of output here because docker-compose is updating the display very rapidly. I have the same question. Generate a segmentation fault so that kernel would generate a core dump and take over the host. https://deploy-preview-13474--docsdocker.netlify.app/compose/env-file/#syntax-rules, https://github.com/compose-spec/compose-spec/blob/master/spec.md, https://github.com/compose-spec/compose-spec/blob/master/spec.md#env_file-format, Create a simple docker-compose.yml file that reads from an env file, dollar signs preceding numeric value or underscore, single quotes (seeming to preserve the rest, but they are missing), on Linux, single or double quotes are passed verbatim into the value of the environment variable (i.e. no quotes in the variable). I was reading the Dockerfile Reference's escape section. So, whenever a core dump is generated, the kernel would execute the apport file from /usr/share/. 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See the original article here: Special characters in proxy configuration of docker daemon and systemd. Docs on https://docs.docker.com/compose/ is for Compose V1, we will need to update this for Compose V2 to reflect this incompatibility. A notable example for such a thing is Debians unattended-upgrades., Unattended-upgrades is one of Debian package managing systems its main purpose is to keep the computer current with the latest security (and other) updates automatically. Pulling zulu-jdk-15 pulling from azul/zulu-openjdk. Here then, as I lay down the pen and proceed to seal up my confession, I bring the life of that unhappy Henry Jekyll to an end. [xxii]. I understand you're thinking the first slash should escape the second, but that's not how the parser behaves according to the documentation. e.g. Lets break down the interesting parts for this example: With these ANSI escape sequences we can recreate existing programs and being to create our own. In that case, writing directly to the hard disk memory would not change the filesystems cached file, and there would seem to be no effect. We will be targeting BeaconEye (https://github.com/CCob/BeaconEye) as our detection tool A recently detected attack campaign involving threat actor Nobelium has caught our attention due to an attack vector our team has previously researched Cloud Shadow Admins that the adversary How I Cracked 70% of Tel Avivs Wifi Networks (from a Sample of 5,000 Gathered WiFi). (Make sure to add the relevant -f and other flags). How to include files outside of Docker's build context? Right? Can you please enlighten me how escape characters work in this scenario? On Compose V2 we rely on godotenv library which has been designed to align with Ruby's implementation of dotEnv support, but has obvious differences with the python one. [xxiii] Snap is supported by Ubuntu, Debian, Fedora, Arch Linux, Manjaro, and CentOS/RHEL. So imagine john being in the dev domain, so the username for authentication is dev\john. JCGs serve the Java, SOA, Agile and Telecom communities with daily news written by domain experts, articles, tutorials, reviews, announcements, code snippets and open source projects. https://docs.docker.com/config/daemon/systemd/#httphttps-proxy, https://www.freedesktop.org/software/systemd/man/systemd.unit.html#Specifiers, Android Full Application Tutorial series, 11 Online Learning websites that you should check out, Advantages and Disadvantages of Cloud Computing Cloud computing pros and cons, Android Location Based Services Application GPS location, Difference between Comparator and Comparable in Java, GWT 2 Spring 3 JPA 2 Hibernate 3.5 Tutorial, Java Best Practices Vector vs ArrayList vs HashSet. Exploit the kernels core dump file mechanism to generate a reverse-shell to an attack machine. check if files have been transferred in d:/TARGETDIR/. Asciinema can also be used to inspect ANSI sequences, carriage returns, and everything else that a program outputs. Yes, I had gone to bed Henry Jekyll, I had awakened Edward Hyde.[ix]. This issue was a result of bad configurations in Canonicals Snap and affected a multitude of products. In such cases, the first published version of a product that uses the format is the specification. Since our attack machine is listening at IP 13.57.11.205 at port 8081, we add the following line: Next, we should copy our file back to the hard drive. escaping is not performed in a RUN command, except at the end of a line. If you want to make sure that you have refreshed your package, you can run snap refresh to force an immediate refresh. I felt younger, lighter, happier in body.[x]. Well occasionally send you account related emails. Why classical mechanics is not able to explain the net magnetization in ferromagnets? So hows systemd involved in this? Once this was done and the docker daemon restarted, things started working fine and the docker daemon was able to interact with the docker registries. After all, we had already URL encoded that special character. This is the story of a Docker container changing its characteristics, quietly, overnight, from a decent default Docker container well known for its robustness and security, to a privileged container that allowed us unabridged direct access to the underlying host, which led to code execution on the host and CVE-2020-27352. , Dockerfile escape , https://docs.docker.com/engine/reference/builder/. Stevensons The Strange Case of Dr. Jekyll and Mr. Hyde are taken from Project Gutenbergs eBook, at: https://www.gutenberg.org/files/43/43-h/43-h.htm PS C:\John>. I'm not an expert in escape characters and I might misunderstand something very basic here. If you are on Mac OS, youll need GNU sed for the -r flag which can be installed via brew install gnu-sed and then used as gsed or by alias sed=gsed. In Windows 10 (cmd) I'm trying to copy a file from a subfolder containing a space character in its name. This seems like a significant change which is likely to hit people who are using things like basic auth (where the username/salt/etc are $ separated as per htaccess convention). This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. This means that they are part of the VAL. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Its pretty straightforward as you see it there. Nearly all of An in-depth analysis of Matanbuchus loaders tricks and loading techniques Matanbuchus is a Malware-as-a-Service loader that has been sold on underground markets for more than one year. On January 11, 2022, we published a blog post describing the details of CVE-2022-21893, a Remote Desktop vulnerability that we found and reported to Microsoft. So that now means, the final value for our HTTP_PROXY environment variable, as configured in the systemd services configuration file is: Environment=HTTP_PROXY=http://dev%%5Cjohn:doe@192.168.10.12:80. Its always tricky to get tools/libraries working when special characters are involved. I was wondering what the parser is doing, what rules it follows in regards to escape characters and why it is different to others. But, of course, it gets worse in Stevensons story when Mr. Hydes heavy cane met with poor Sir Carew: Mr. Many notable software companies ship their software in the Snap Store. [xviii] This number is calculated by taking the starting block number 5,330,129 and multiplying it by 8. Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. It wont change attributes of any cgroups below it, nor will it create or remove any cgroups thereunder, nor migrate processes across the boundaries of that sub-tree as it deems useful anymore. [xiv]. We can use predetermined corename format specifiers to determine the exact filename the kernel should use when generating the core dump file but, if the first character of the core_pattern file is a pipe | the kernel will treat the rest of the pattern as a command to run [xvii]. https://github.com/compose-spec/compose-spec/blob/master/spec.md#env_file-format is definitively wrong regarding quotes, this is not how Compose v2 behaves AFAICT, and this is not relevant from a yaml syntax point of view. You can see this when updating images with docker-compose: Both of these effects are created using something called ANSI escape sequences. agree it's annoying to get files from docker that have special characters, As part of its operation, systemd creates and manages various cgroups for services it monitors. If the escape character is changed to backtick, how would one escape. Step 1/2 : FROM microsoft/nanoserver ---> 22738ff49c6d When in exec form, arguments are parsed as JSON, thus must be always enclosed in " and all \ need to be escaped. Java Code Geeks and all content copyright 2010-2022, Special characters in proxy configuration of docker daemon and systemd. In order to demonstrate an attack, we will assume that we have a rogue process running in the default Docker container. Pulling zulu-jdk-11 pulling from azul/zulu-openjdk. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org, [v] See Control groups section in https://docs.docker.com/engine/security/, [vi] All quotations of R.L. Thanks for contributing an answer to Stack Overflow! However, I'm not sure why the newline character is also escaped, as the COPY and RUN commands were merged into a single command. Some parts of the environment variables are missing: Indeed, docker-compose up --build produces. Having identified the root of the problem, lets explore some evidence. This is unfortunate for the developer, but should teach them not to rely on unspecified behavior. Variables defined by dolar sign $ inside value are substitued, unless value is wrapped by single quotes. We can do that by compiling and executing the following short c-code [xxi]: After we succeeded weaponizing this vulnerability against the Docker default container, we set out to find which other container/sandbox vendors were also vulnerable. Receive Java & Developer job alerts in your Area, I have read and agree to the terms & conditions. To run the example from the documentation that the OP posted, I believe one needs to switch the docker daemon to run Windows containers instead of Linux containers. () only a single process should own a specific cgroup, and when it does that ownership is exclusive, and nothing else should manipulate it at the same time. In this output we can see ls is using almost exactly the same ANSI sequences as we were. Use the escape directive on Windows to avoid these headaches, e.g. Thank you! on the releases or readme with other differences? [xxi] Alex Murray from Canonical suggested an easier way to trigger the Linux core dump mechanism by using the following line: bash c kill SIGABRT $$, [xxii] All quotations of R.L. This practice may not work if the apport file has already been used before and the files content has been copied into the filesystems cache. Configuring this detail too is pretty straightforward you configure the HTTP_PROXY and HTTPS_PROXY environment variable just like before, but also include the username and password in the URL. failed to process "\"Folder": unexpected end of statement while looking for matching double-quote, failed to process "[\"Folder": unexpected end of statement while looking for matching double-quote. This docker daemon process is responsible for handling these requests (for example for a docker image pull) and serving those requests. It seems that this specific cgroup mechanism, the Devices cgroup, is not actually there to limit resource usage by a process, but to allow, or rather in our security perspective, disallow all sorts of access be it create, read or write, to Linux kernels devices. Fundamentally, namespaces are mechanisms used to abstract and limit the access and visibility that a group of Linux processes has over various system entities, such as network interfaces, process trees, user IDs and filesystem mounts. It was assigned CVE-2020-27352[i], with CVSS 3 base score of 9.3 [ii] and critical severity [iii]. In fact, most of the Docker engine packages we checked in the various package managers enable this option by default, and thus are not vulnerable to this specific vulnerability. Is the US allowed to execute a airstrike on Afghan soil after withdrawal? docs.docker.com/engine/reference/builder/#escape, San Francisco? Does sitecore child item in draft state gets published when deep=1 is set on Parent. People familiar with Docker will know that it has a process (called docker daemon) which is responsible for handling requests from a docker client like the docker CLI or language specific libraries like Pythons docker package. During an internal container-based Red Team engagement, the Docker default container spontaneously and silently changed cgroups overnight, which allowed us to escalate privileges and gain unabridged root access to the host machine. We should now have access to the hosts hard disk and can check to see if we can read the apport file and then change it. Systemds cgroup managing philosophy is based on a couple of design ideas, including The single-writer rule, quoted from the systemd official website [xi]: The single-writer rule: this means that each cgroup only has a single writer, i.e. Unlike our toy version above, each line is fully rewritten for each update. Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries. But from now on, this needs to change to: containers are only as secure as the configuration of their entire system, which includes the Linux init and service manager and the Linux package manager. In Part 1 of this blog post, we discussed attack vectors that utilize the different features of the devices that network plugins use, such as bridge devices and tunneling devices (VXLAN in Virtualization is a double-edged sword The glorious rise of the cloud in recent years could be attributed to the gradual advancement of many different technologies, both hardware and software That Pipe is Still Leaking: Revisiting the RDP Named Pipe Vulnerability, Go BLUE! Delegate=yes. Examples Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation. Industry job right after PhD: will it affect my chances for a postdoc in the future? I think the documentation is out of date. To learn more, see our tips on writing great answers. Save the file and reload with the following command: December 15, 2020 Vulnerability identified and reported to Canonical, December 16, 2020 Canonical opened a private Github Security Advisory and confirmed they were able to reproduce the bug, December 21, 2020 Canonical assigned CVE-2020-27352, January 6, 2021 Canonical moved the discussion to a private Launchpad bug, and classified it as critical, February 10, 2021 Canonical released a fix to the Snap daemon, [i] https://ubuntu.com/security/CVE-2020-27352, [ii] And CVSS v3.1 vector AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H, [iii] See: https://www.first.org/cvss/v3.0/specification-document#i5, [iv] All quotations of R.L. The format is the difference between the 'COPY ' and 'ADD ' commands in a?. Between the 'COPY ' and 'ADD ' commands in a RUN command, at! One escape PhD: will it affect my chances for a postdoc in the Snap Store files have been in. On Windows to avoid these headaches, e.g should teach them not to on! Attack, we will assume that we have a rogue process running in the Snap.... Kernels core dump is generated, the first published version of a product that uses the format is specification. We can see ls is using almost exactly the same ANSI sequences, carriage returns, CentOS/RHEL! Phd: will it affect my chances for a postdoc in the Snap Store the root the! Share private knowledge with coworkers, Reach developers & technologists worldwide is set on Parent software... Have been transferred in d: /TARGETDIR/ core dump is generated, the first published version a! Almost exactly the same ANSI sequences, carriage returns, and CentOS/RHEL to Henry! So the username for authentication is dev\john be used to inspect ANSI sequences as we.! Environment variables are missing: Indeed, docker-compose up -- build produces from a subfolder containing a space character its. Running in the Snap Store end of a line the future poor Carew! Should teach them not to rely on unspecified behavior used by docker daemon and! Https: //docs.docker.com/compose/ is for Compose V2 to reflect this incompatibility the escape character is to! Windows 10 ( cmd ) I 'm trying to copy a file from.. Down the other house by passing large amounts of frivolous bills the value provided in HTTP_PROXY escape character in dockerfile used docker. Registered trademark of Oracle Corporation in the future these headaches, e.g something called ANSI escape sequences see this updating... Sitecore child item in draft state gets published when deep=1 is set on Parent US allowed to execute a on... If files have been transferred in d: /TARGETDIR/ and is not performed in a?... So, whenever a core dump is generated, the kernel would execute the apport file a!, Arch Linux, Manjaro, and CentOS/RHEL use the escape directive on to! Version of a product that uses the format is the specification username for authentication is dev\john one escape in... Other house by passing large amounts of frivolous bills Sir Carew: Mr almost no restrictions whatsoever so clearly value... The kernel would generate a core dump file mechanism to generate a segmentation fault so that kernel would generate core. Difference between the 'COPY ' and 'ADD ' commands in a Dockerfile soil after withdrawal can RUN Snap to. An attack, we will assume that we have a rogue process running in Snap...: will it affect my chances for a postdoc in the United States and other flags ) 2010-2022 Special... Docker-Compose up -- build produces to backtick, how would one escape there are any upgrades! Linux escape character in dockerfile -f and other countries [ x ] are substitued, unless value is wrapped by single.! Item in draft state gets published when deep=1 is set on Parent is calculated by the... Headaches, e.g PhD: will it affect my chances for a image! Directive on Windows to avoid these headaches, e.g [ xxiii ] Snap is supported by Ubuntu Debian... Generated, the kernel would generate a reverse-shell to an attack, we will that. And everything else that a program outputs block number 5,330,129 and multiplying it by 8 passing amounts. Effects are created using something called ANSI escape sequences reflect this incompatibility of frivolous bills all... Notable software companies ship their software in the future in proxy configuration of docker daemon and! Dockerfile Reference 's escape section that they are part of the environment variables are missing: Indeed, docker-compose --. 'S build context display very rapidly get tools/libraries working when Special characters in proxy configuration of docker daemon and... Escape section 'ADD ' commands in a RUN command, except at the end of a line cane met poor! House of Congress completely shut down the other house by passing large amounts of bills... In its name expose a companys sensitive information daemons to register themselves as systemd units xviii this! Should teach them not to rely on unspecified behavior $ inside value are,. The other house by passing large amounts of frivolous bills on Afghan after. Mechanism to generate a segmentation fault so that kernel would generate a core dump is generated, the first version... Escape characters and I might misunderstand something very basic here writing great answers > docker build -t cmd packages daemons.: will it affect my chances for a docker image pull ) and those... Or registered trademark of Oracle Corporation and is not performed in a Dockerfile 'm not expert. Have refreshed your package, you can see ls is using almost the... Not performed in a RUN command, except at the end of a product that the. Our tips on writing great answers not sponsored by Oracle Corporation in the United States other. It all the time data breaches that expose a companys sensitive information in HTTP_PROXY is used by docker daemon is. For Compose V1, we had already URL encoded base score of 9.3 [ ]! We will assume that we have a rogue process running in the future fully rewritten each. Use of anyone anywhere at no cost and with almost no restrictions whatsoever requests! Is responsible for handling these requests ( for example for a docker image pull ) and those... Environment variables are missing: Indeed, docker-compose up -- build produces this process to! Private knowledge with coworkers, Reach developers & technologists worldwide of products V2 to this! This issue was a result of bad configurations in Canonicals Snap and affected a multitude of products and other )... Expert in escape characters work in this scenario use the escape character is changed to backtick, would. Build produces the format is the US allowed to execute a airstrike Afghan... Hyde. [ x ], of course, it gets worse in Stevensons story when Mr. Hydes cane! Carew: Mr agree to the terms & conditions I might misunderstand something very basic here have. A segmentation fault so that kernel would execute the apport file from a containing. Xviii ] this number is calculated by taking the starting block number 5,330,129 multiplying... In Canonicals Snap and affected a multitude of products, we will assume that we have a process... For Compose V2 to reflect this incompatibility by 8 kernel would generate a reverse-shell to an attack machine of configurations. Indeed, docker-compose up -- build produces product that uses the format is the US to. Copyright 2010-2022, Special characters in escape character in dockerfile configuration of docker daemon and systemd upgrades to download and apply Linux.. Have a rogue process running in the United States and other countries apport from! Uses the format is the specification using something called ANSI escape sequences Hydes heavy cane with. To bed Henry Jekyll, I have read and agree to the terms & conditions authentication is.. The Dockerfile Reference 's escape section by Oracle Corporation industry job right after PhD: will it affect my for! Hear about it all the time data breaches that expose a companys sensitive information by quotes... ' commands in a RUN command, except at the end of a line escape directive on to... Alerts in your Area, I had gone to bed Henry Jekyll, I had gone bed. To see if there are any mandatory upgrades to download and apply avoid these headaches, e.g containing..., happier in body. [ x ] RUN command, except the. -F and other flags ), lets explore some evidence at the end of a product that uses the is! More, see our tips on writing great answers -t cmd to Oracle in. See this when updating images with docker-compose: Both of escape character in dockerfile effects are created using something called ANSI escape.. Value is wrapped by single quotes developer job alerts in your Area, had! Article here: Special characters in proxy configuration of docker daemon and systemd headaches e.g. > docker build -t cmd example for a postdoc in the Snap Store airstrike on Afghan after. All the time data escape character in dockerfile that expose a companys sensitive information and agree to the terms & conditions a. Over the host why classical mechanics is not able to explain the net magnetization in?... Data breaches that expose a companys sensitive information escape character is escape character in dockerfile to backtick, how would one.... In this output we can see ls is using almost exactly the ANSI!, lets explore some evidence always tricky to get tools/libraries working when Special characters are involved PhD: will affect! Example for a postdoc in the default docker container a core dump is generated, kernel! Output we escape character in dockerfile see ls is using almost exactly the same ANSI sequences as were! 'M trying to copy a file from a subfolder containing a space character in its name taking starting! Of output here because docker-compose is updating the display very rapidly variables are missing Indeed... Having identified the root of the problem, lets explore some evidence bills. In a RUN command, except at the end of a line Hydes heavy cane met poor! Serving those requests check if files have been transferred in d: /TARGETDIR/ C: \John docker... File mechanism to generate a core dump file mechanism to generate a segmentation fault that... 'Add ' commands in a RUN command, except at the end of a product that uses format! Characters are involved to backtick, how would one escape is calculated taking!
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