Fixes#9590: Block explicit sudo -S (stdin password mode) commands
when the SUDO_PASSWORD environment variable is not configured.
The attack vector: the LLM constructs 'echo guessedpass | sudo -S cmd'
to brute-force sudo passwords, iterates based on sudo's error output
('Sorry, try again'). The existing _transform_sudo_command only
injects -S when SUDO_PASSWORD exists; without it, the LLM's explicit
sudo -S must be treated as a guessing attempt.
Changes:
- Add _check_sudo_stdin_guard() in approval.py: detects sudo -S when
SUDO_PASSWORD is absent, anchored to command-start positions
(^ ; && || | etc.) to avoid false positives on literal text
- Integrate into check_all_command_guards() above yolo/mode=off so
the block is unconditional (like the hardline floor)
- Add 6 tests covering: detection, allow-list, SUDO_PASSWORD bypass,
integration with check_all_command_guards, yolo non-bypass,
container backend bypass
Adds a floor below --yolo: a tiny set of commands so catastrophic they
should never run via the agent, regardless of --yolo, gateway /yolo,
approvals.mode=off, or cron approve mode. Opting into yolo is trusting
the agent with your files and services — not trusting it to wipe the
disk or power the box off.
The list is deliberately small (12 patterns), covering only
unrecoverable ops:
- rm -rf targeting /, /home, /etc, /usr, /var, /boot, /bin, /sbin,
/lib, ~, $HOME
- mkfs (any variant)
- dd + redirection to raw block devices (/dev/sd*, /dev/nvme*, etc.)
- fork bomb
- kill -1 / kill -9 -1
- shutdown, reboot, halt, poweroff, init 0/6, telinit 0/6,
systemctl poweroff/reboot/halt/kexec
Recoverable-but-costly commands (git reset --hard, rm -rf /tmp/x,
chmod -R 777, curl | sh) stay in DANGEROUS_PATTERNS where yolo can
still pass them through — that's what yolo is for.
Container backends (docker/singularity/modal/daytona) continue to
bypass both hardline and dangerous checks, since nothing they do can
touch the host.
Inspired by Mercury Agent's permission-hardened blocklist.
