Cyrene
aa0bb45633
Three independent root causes, all found by measuring instead of assuming:
1. SSH failed on 10/16 challenges while state.json looked perfect.
Only the 6 native GEMASTIK XVIII images provision 'ctfuser'; every imported
XVI/XVII image does 'echo root:${PASSWORD} | chpasswd' and logs in as root.
set_ssh_passwords() hardcoded ctfuser, so chpasswd set a password nobody
used -> 'Permission denied' on every team. Registry gains a per-challenge
'ssh_user'; chpasswd targets the real login and reports failures loudly.
2. phew SLA timed out on a healthy service, four bugs stacked:
- chall.py block-buffers stdout through the exec pipe (PYTHONUNBUFFERED now
set) and does a fresh Pailier keygen (~12 s) before printing its menu;
- _read_until read a TEXT pipe, so read(1) pulled 8 KB into Python's
TextIOWrapper buffer and select() then blocked on data already in memory;
- its buffer was per-call, so the read satisfying 'pt (hex)' also swallowed
the '> ' the next call waited for -> a race that failed intermittently;
- reaping killed chall.py it did not own: a blanket pkill -f, a
snapshot-diff (concurrent sessions diff against the same pre-spawn set),
and a class-level _children shared across uvicorn's thread pool. The child
now prints its own pid so exactly one session is reaped.
Also: ONE interactive session per check instead of five spawns (Paillier is
randomized per ciphertext, not per process) - 5 keygens were the CPU load
that starved the checks. And the 6 orphan single-node containers from the
original deploy were removed; one held 58 leaked chall.py and drove load
average 76 on 2 CPUs.
3. missing_sidecars() matched compose-generated names (teamN-<svc>-1) while
every service sets an explicit container_name, so it reported all 16 running
challenges as missing and hid the one real gap (anti-alchemy-db, which has
no container_name). Now reads container_name when present and falls back to
the compose default otherwise.
Verified: 64/64 SLA across 4 teams; 64/64 real SSH logins succeed with
correct <chall>_teamN hostnames; phew 3/3 sequential with no process leak.
Adds panel/verify_ssh_creds.py, audit_ssh_users.sh, reset_runtime.sh,
sla_sweep.sh, fix_sidecars.sh, phew_concurrency_test.sh, exec_probe_i.py.
Gemastik XVIII Cybersecurity Final Round - Attack Defense Repository
challenges
| challenges | author | category |
|---|---|---|
| blogpost | keii | web |
| cdn | keii | foren |
| phew | itoid | crypto |
| sheesh | itoid | crypto |
| carbeat | rui | pwn |
| warmup | hanz0 | warmup |
how-to-run
sudo python3 starter.py