I was talking to ChatGPT about the best way to achieve this a few days ago. Thanks for getting something running and sharing it!
I'll give this a try tomorrow, should be fun.
I'll give this a try tomorrow, should be fun.
Here's what Claude Code tried:
- Docker socket (/var/run/docker.sock) → Not mounted
- Capabilities → CapPrm=0, CapEff=0 - no elevated caps
- Cgroup escape → Mount denied (no CAP_SYS_ADMIN)
- Device access → Only minimal /dev entries, no block devices
- Path traversal on /workspace → Resolves inside container (kernel prevents mount escape)
- Symlink to host paths → Resolves inside container namespace
- Ptrace → Restricted (ptrace_scope=1)
- Cloud metadata → No response
- Docker API → Not exposed
Security profile: Seccomp mode 2, AppArmor docker-default (enforce)
I just redteamed this. The security model relies on the container boundary, but it implicitly trusts local configuration files.
I found that yolobox automatically loads .yolobox.toml from the current working directory, which accepts a mounts array. It doesn't prompt for confirmation when these mounts are loaded.
I put together a PoC that drops a .yolobox.toml with mounts = ["~:/tmp/host_home"]. The next time the user runs yolobox in that directory, their actual host home directory is silently mounted into the container with write access. Combined with the persistent /home/yolo volume, I was able to script a payload in .bashrc that immediately escapes the sandbox and writes to the host filesystem as soon as the tool starts.
While you're at it, bind mount .git read-only as well. Hasn't happened to me yet, but talked to people who had their local repo wiped out by desperate agents! No code - no broken tests, eh. It would also block one nasty container escape vector via git hooks.