84 lines
4.8 KiB
Markdown
84 lines
4.8 KiB
Markdown
<!--[metadata]>
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+++
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title = "Docker Security Non-events"
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description = "Review of security vulnerabilities Docker mitigated"
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keywords = ["Docker, Docker documentation, security, security non-events"]
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[menu.main]
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parent = "smn_secure_docker"
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+++
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<![end-metadata]-->
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# Docker Security Non-events
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This page lists security vulnerabilities which Docker mitigated, such that
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processes run in Docker containers were never vulnerable to the bug—even before
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it was fixed. This assumes containers are run without adding extra capabilities
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or not run as `--privileged`.
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The list below is not even remotely complete. Rather, it is a sample of the few
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bugs we've actually noticed to have attracted security review and publicly
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disclosed vulnerabilities. In all likelihood, the bugs that haven't been
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reported far outnumber those that have. Luckily, since Docker's approach to
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secure by default through apparmor, seccomp, and dropping capabilities, it
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likely mitigates unknown bugs just as well as it does known ones.
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Bugs mitigated:
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* [CVE-2013-1956](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1956),
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[1957](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1957),
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[1958](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1958),
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[1959](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1959),
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[1979](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1979),
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[CVE-2014-4014](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-4014),
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[5206](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-5206),
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[5207](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-5207),
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[7970](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-7970),
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[7975](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-7975),
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[CVE-2015-2925](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-2925),
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[8543](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-8543),
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[CVE-2016-3134](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-3134),
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[3135](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-3135), etc.:
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The introduction of unprivileged user namespaces lead to a huge increase in the
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attack surface available to unprivileged users by giving such users legitimate
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access to previously root-only system calls like `mount()`. All of these CVEs
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are examples of security vulnerabilities due to introduction of user namespaces.
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Docker can use user namespaces to set up containers, but then disallows the
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process inside the container from creating its own nested namespaces through the
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default seccomp profile, rendering these vulnerabilities unexploitable.
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* [CVE-2014-0181](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0181),
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[CVE-2015-3339](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3339):
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These are bugs that require the presence of a setuid binary. Docker disables
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setuid binaries inside containers via the `NO_NEW_PRIVS` process flag and
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other mechanisms.
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* [CVE-2014-4699](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-4699):
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A bug in `ptrace()` could allow privilege escalation. Docker disables `ptrace()`
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inside the container using apparmor, seccomp and by dropping `CAP_PTRACE`.
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Three times the layers of protection there!
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* [CVE-2014-9529](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-9529):
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A series of crafted `keyctl()` calls could cause kernel DoS / memory corruption.
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Docker disables `keyctl()` inside containers using seccomp.
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* [CVE-2015-3214](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3214),
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[4036](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-4036): These are
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bugs in common virtualization drivers which could allow a guest OS user to
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execute code on the host OS. Exploiting them requires access to virtualization
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devices in the guest. Docker hides direct access to these devices when run
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without `--privileged`. Interestingly, these seem to be cases where containers
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are "more secure" than a VM, going against common wisdom that VMs are
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"more secure" than containers.
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* [CVE-2016-0728](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-0728):
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Use-after-free caused by crafted `keyctl()` calls could lead to privilege
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escalation. Docker disables `keyctl()` inside containers using the default
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seccomp profile.
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* [CVE-2016-2383](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2383):
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A bug in eBPF -- the special in-kernel DSL used to express things like seccomp
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filters -- allowed arbitrary reads of kernel memory. The `bpf()` system call
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is blocked inside Docker containers using (ironically) seccomp.
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Bugs *not* mitigated:
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* [CVE-2015-3290](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3290),
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[5157](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-5157): Bugs in
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the kernel's non-maskable interrupt handling allowed privilege escalation.
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Can be exploited in Docker containers because the `modify_ldt()` system call is
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not currently blocked using seccomp.
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