CVE-2024-45310: runc can be confused to create empty files/directories on the host
Impact runc 1.1.13 and earlier as well as 1.2.0-rc2 and earlier can be tricked into creating empty files or directories in arbitrary locations in the host filesystem by sharing a volume between two containers and exploiting a race with os.MkdirAll. While this can be used to create empty files, existing files will not be truncated.
An attacker must have the ability to start containers using some kind of custom volume configuration. Containers using user namespaces are still affected, but the scope of places an attacker can create inodes can be significantly reduced. Sufficiently strict LSM policies (SELinux/Apparmor) can also in principle block this attack -- we suspect the industry standard SELinux policy may restrict this attack's scope but the exact scope of protection hasn't been analysed.
This is exploitable using runc directly as well as through Docker and Kubernetes.
The CVSS score for this vulnerability is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N (Low severity, 3.6).
Workarounds Using user namespaces restricts this attack fairly significantly such that the attacker can only create inodes in directories that the remapped root user/group has write access to. Unless the root user is remapped to an actual user on the host (such as with rootless containers that don't use /etc/sub[ug]id), this in practice means that an attacker would only be able to create inodes in world-writable directories.
A strict enough SELinux or AppArmor policy could in principle also restrict the scope if a specific label is applied to the runc runtime, though we haven't thoroughly tested to what extent the standard existing policies block this attack nor what exact policies are needed to sufficiently restrict this attack.
Patches Fixed in runc v1.1.14 and v1.2.0-rc3.
main patches: https://github.com/opencontainers/runc/pull/4359 https://github.com/opencontainers/runc/commit/63c2908164f3a1daea455bf5bcd8d363d70328c7 release-1.1 patches: https://github.com/opencontainers/runc/commit/8781993968fd964ac723ff5f360b6f259e809a3e https://github.com/opencontainers/runc/commit/f0b652ea61ff6750a8fcc69865d45a7abf37accf
Credits Thanks to Rodrigo Campos Catelin (@rata) and Alban Crequy (@alban) from Microsoft for discovering and reporting this vulnerability.
Other sources
runc can be confused to create empty files/directories on the host
— Microsoft
runc is a CLI tool for spawning and running containers according to the OCI specification. runc 1.1.13 and earlier, as well as 1.2.0-rc2 and earlier, can be tricked into creating empty files or directories in arbitrary locations in the host filesystem by sharing a volume between two containers and exploiting a race with os.MkdirAll. While this could be used to create empty files, existing files would not be truncated. An attacker must have the ability to start containers using some kind of custom volume configuration. Containers using user namespaces are still affected, but the scope of places an attacker can create inodes can be significantly reduced. Sufficiently strict LSM policies (SELinux/Apparmor) can also in principle block this attack -- we suspect the industry standard SELinux policy may restrict this attack's scope but the exact scope of protection hasn't been analysed. This is exploitable using runc directly as well as through Docker and Kubernetes. The issue is fixed in runc v1.1.14 and v1.2.0-rc3.
Some workarounds are available. Using user namespaces restricts this attack fairly significantly such that the attacker can only create inodes in directories that the remapped root user/group has write access to. Unless the root user is remapped to an actual user on the host (such as with rootless containers that don't use /etc/sub[ug]id), this in practice means that an attacker would only be able to create inodes in world-writable directories. A strict enough SELinux or AppArmor policy could in principle also restrict the scope if a specific label is applied to the runc runtime, though neither the extent to which the standard existing policies block this attack nor what exact policies are needed to sufficiently restrict this attack have been thoroughly tested.
— MITRE
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2024-45310?
CVE-2024-45310 is classified as a medium severity vulnerability due to its potential impact on file system integrity.
How do I fix CVE-2024-45310?
To remediate CVE-2024-45310, upgrade to runc version 1.1.14 or 1.2.0-rc.3 or later.
What causes CVE-2024-45310?
CVE-2024-45310 is caused by a race condition in the handling of volume mounts between containers.
Which versions of runc are affected by CVE-2024-45310?
Both runc version 1.1.13 and earlier as well as 1.2.0-rc2 and earlier are affected by CVE-2024-45310.
How can CVE-2024-45310 be exploited?
CVE-2024-45310 can be exploited by attackers to create empty files or directories in arbitrary locations on the host filesystem.