runc container breakout through process.cwd trickery and leaked fds

Vulnerability Description

runc is a CLI tool for spawning and running containers on Linux according to the OCI specification. In runc 1.1.11 and earlier, due to an internal file descriptor leak, an attacker could cause a newly-spawned container process (from runc exec) to have a working directory in the host filesystem namespace, allowing for a container escape by giving access to the host filesystem ("attack 2"). The same attack could be used by a malicious image to allow a container process to gain access to the host filesystem through runc run ("attack 1"). Variants of attacks 1 and 2 could be also be used to overwrite semi-arbitrary host binaries, allowing for complete container escapes ("attack 3a" and "attack 3b"). runc 1.1.12 includes patches for this issue.

References

• https://github.com/opencontainers/runc/security/advisories/GHSA-xr7r-f8xq-vfvv
• https://github.com/opencontainers/runc/commit/02120488a4c0fc487d1ed2867e901eeed7ce8ecf
• https://github.com/opencontainers/runc/releases/tag/v1.1.12
• http://www.openwall.com/lists/oss-security/2024/02/01/1
• http://www.openwall.com/lists/oss-security/2024/02/02/3
• http://packetstormsecurity.com/files/176993/runc-1.1.11-File-Descriptor-Leak-Privilege-Escalation.html
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SYMO3BANINS6RGFQFKPRG4FIOJ7GWYTL/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2NLXNE23Q5ESQUAI22Z7A63JX2WMPJ2J/
• https://lists.debian.org/debian-lts-announce/2024/02/msg00005.html