4 ms·

If the container is running in privileged mode you can just talk to the docker socket to the daemon on the host, spawn a new container with direct access to the

If the container is running in privileged mode you can just talk to the docker socket to the daemon on the host, spawn a new container with direct access to the root filesystem, and then change anything you want as root.

CGamesPlay 10mo ago
Notably, if you run docker-in-docker, Docker is probably not a security boundary. Try this inside any dind container (especially devcontainers): docker run -it --rm --pid=host --privileged -v /:/mnt alpine sh I disagree with other commenters here that Docker is not a security boundary. It's a fine one, as long as you don't disable the boundary, which is as easy as running a container with `--privileged`. I wrote about secure alternatives for devcontainers here: https://cgamesplay.com/recipes/devcontainers/#docker-in-devcontainer https://cgamesplay.com/recipes/devcontainers/#docker-in-devc...
- flaminHotSpeedo 10mo ago
  Containers are never a security boundary. If you configure them correctly, avoid all the footguns, and pray that there's no container escape vulnerabilities that affect "correctly" configured containers then they can be a crude approximation of a security boundary that may be enough for your use case, but they aren't a suitable substitute for hardware backed virtualization. The only serious company that I'm aware of which doesn't understand that is Microsoft, and the reason I know that is because they've been embarrassed again and again by vulnerabilities that only exist because they run multitenant systems with only containers for isolation
  - vel0city 10mo ago
    Virtual machines are never a security boundary. If you configure them correctly, avoid all the footguns, and pray that there's no VM escape vulnerabilities that affect "correctly" configured VMs then they can be a crude approximation of a security boundary that may be enough for your use case, but they aren't a suitable substitute for entirely separate hardware. Its all turtles, all the way down.
    - flaminHotSpeedo 10mo ago
      Yeah, in some (rare) situations physical isolation is a more appropriate level of security. Or if you want to land somewhere in between, you can use VM's with single tenant NUMA nodes. But for a typical case, VM's are the bare minimum to say you have a _secure_ isolation boundary because the attack surface is way smaller.
      - vel0city 10mo ago
        Yeah, so secure. https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/25390 https://support.broadcom.com/web/ecx/support-content-notific... https://nvd.nist.gov/vuln/detail/CVE-2019-5183 https://nvd.nist.gov/vuln/detail/CVE-2019-5183 https://nvd.nist.gov/vuln/detail/CVE-2018-12130 https://nvd.nist.gov/vuln/detail/CVE-2018-12130 https://nvd.nist.gov/vuln/detail/CVE-2018-2698 https://nvd.nist.gov/vuln/detail/CVE-2018-2698 https://nvd.nist.gov/vuln/detail/CVE-2017-4936 https://nvd.nist.gov/vuln/detail/CVE-2017-4936 In the end you need to configure it properly and pray there's no escape vulnerabilities. The same standard you applied to containers to say they're definitely never a security boundary. Seems like you're drawing some pretty arbitrary lines here.

CGamesPlay 10mo ago

Notably, if you run docker-in-docker, Docker is probably not a security boundary. Try this inside any dind container (especially devcontainers): docker run -it --rm --pid=host --privileged -v /:/mnt alpine sh I disagree with other commenters here that Docker is not a security boundary. It's a fine one, as long as you don't disable the boundary, which is as easy as running a container with `--privileged`. I wrote about secure alternatives for devcontainers here: https://cgamesplay.com/recipes/devcontainers/#docker-in-devcontainer https://cgamesplay.com/recipes/devcontainers/#docker-in-devc...

flaminHotSpeedo 10mo ago
Containers are never a security boundary. If you configure them correctly, avoid all the footguns, and pray that there's no container escape vulnerabilities that affect "correctly" configured containers then they can be a crude approximation of a security boundary that may be enough for your use case, but they aren't a suitable substitute for hardware backed virtualization. The only serious company that I'm aware of which doesn't understand that is Microsoft, and the reason I know that is because they've been embarrassed again and again by vulnerabilities that only exist because they run multitenant systems with only containers for isolation
- vel0city 10mo ago
  Virtual machines are never a security boundary. If you configure them correctly, avoid all the footguns, and pray that there's no VM escape vulnerabilities that affect "correctly" configured VMs then they can be a crude approximation of a security boundary that may be enough for your use case, but they aren't a suitable substitute for entirely separate hardware. Its all turtles, all the way down.
  - flaminHotSpeedo 10mo ago
    Yeah, in some (rare) situations physical isolation is a more appropriate level of security. Or if you want to land somewhere in between, you can use VM's with single tenant NUMA nodes. But for a typical case, VM's are the bare minimum to say you have a _secure_ isolation boundary because the attack surface is way smaller.
    - vel0city 10mo ago
      Yeah, so secure. https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/25390 https://support.broadcom.com/web/ecx/support-content-notific... https://nvd.nist.gov/vuln/detail/CVE-2019-5183 https://nvd.nist.gov/vuln/detail/CVE-2019-5183 https://nvd.nist.gov/vuln/detail/CVE-2018-12130 https://nvd.nist.gov/vuln/detail/CVE-2018-12130 https://nvd.nist.gov/vuln/detail/CVE-2018-2698 https://nvd.nist.gov/vuln/detail/CVE-2018-2698 https://nvd.nist.gov/vuln/detail/CVE-2017-4936 https://nvd.nist.gov/vuln/detail/CVE-2017-4936 In the end you need to configure it properly and pray there's no escape vulnerabilities. The same standard you applied to containers to say they're definitely never a security boundary. Seems like you're drawing some pretty arbitrary lines here.