Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ariana-dot-dev/cloud-sandbox-vm-skills --skill run-untrusted-codegit clone --depth 1 https://github.com/ariana-dot-dev/cloud-sandbox-vm-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ariana-dot-dev/cloud-sandbox-vm-skills/run-untrusted-code)<a href="https://agentmods.dev/skills/ariana-dot-dev/cloud-sandbox-vm-skills/run-untrusted-code"><img src="https://agentmods.dev/badge/skills/ariana-dot-dev/cloud-sandbox-vm-skills/run-untrusted-code/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ariana-dot-dev/cloud-sandbox-vm-skills/run-untrusted-code"><img src="https://agentmods.dev/badge/skills/ariana-dot-dev/cloud-sandbox-vm-skills/run-untrusted-code.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00061 | $0.00375 |
| Opus 5.5 | $0.00024 | $0.00150 |
| Sonnet 5.5 | $0.00012 | $0.00075 |
| Haiku 4.5 | $0.00006 | $0.00038 |
Grade C, and why
run-untrusted-code scanned grade C with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Downloads and executes remote codehighSupply chain
curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.
`curl -fsSL https://box.ascii.dev/install | sh`, then `box login "$BOX_API_KEY" --json`. Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
`curl -fsSL https://box.ascii.dev/install | sh`, then `box login "$BOX_API_KEY" --json`. What it actually says
Run untrusted code (Box)
Use this right before executing code you generated or fetched when running it locally would be risky: shell scripts, scraped snippets, dependency installs, anything with side effects. Pattern: create → run → delete, so nothing touches the host.
Why Box
- Isolation — a separate VM; the host filesystem and network are never exposed.
- Disposable & cheap —
box deletewhen done; per-second billing, a run costs cents. - Real machine — generated code that needs
pip install, subprocesses, or Docker actually works.
Prefer another tool for: thousands of tiny <500 ms runs (E2B/Modal microVMs).
Prereqs
curl -fsSL https://box.ascii.dev/install | sh, then box login "$BOX_API_KEY" --json.
Recipe
box_id="$(box new --json | jq -r 'select(.event == "ready") | .id')"
trap 'box delete "$box_id" --json' EXIT # never leak a VM
box ssh "$box_id" -- "mkdir -p /run && cat > /run/main.sh" < ./main.sh
box ssh "$box_id" -- "cd /run && timeout 120 bash main.sh"
Always wrap in timeout and delete in a trap/finally.
Limits
EU-only; disk-level snapshots; 100 active VMs soft cap.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 36 lines · 61 tokens per session scan C d06e6ce5e5d2
run-untrusted-code is a skill published in the GitHub repository ariana-dot-dev/cloud-sandbox-vm-skills (3 stars, last pushed 1mo ago), licensed MIT. It adds 61 tokens to every session and 375 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it C with 2 findings (downloads and executes remote code, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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