The /opt/emit_capture.py, /opt/syslog_bridge.py, and
/usr/libexec/udev/journal-relay files were plaintext and world-readable
to any attacker root-shelled into the SSH honeypot — revealing the full
capture logic on a single cat.
Pack all three into /entrypoint.sh as XOR+gzip+base64 blobs at build
time (_build_stealth.py), then decode in-memory at container start and
exec the capture loop from a bash -c string. No .py files under /opt,
no journal-relay file under /usr/libexec/udev, no argv_zap name
anywhere. The LD_PRELOAD shim is installed as
/usr/lib/x86_64-linux-gnu/libudev-shared.so.1 — sits next to the real
libudev.so.1 and blends into the multiarch layout.
A 1-byte random XOR key is chosen at image build so a bare
'base64 -d | gunzip' probe on the visible entrypoint returns binary
noise instead of readable Python.
Docker-dependent tests live under tests/docker/ behind a new 'docker'
pytest marker (excluded from the default run, same pattern as fuzz /
live / bench).
The named pipe at /run/systemd/journal/syslog-relay had two problems
beyond its argv leak: any root-in-container process could (a) `cat`
the pipe and watch the live SIEM feed, and (b) write to it and inject
forged log lines. Since an attacker with a shell is already root
inside the honeypot, file permissions can't fix it.
Point rsyslog's auth/user actions directly at /proc/1/fd/1 — the
container-stdout fd Docker attached to PID 1 — and delete the
mkfifo + cat relay from the entrypoint. No pipe on disk, nothing to
read, nothing to inject, and one fewer cloaked process in `ps`.
Two leaks remained after the inotifywait argv fix:
1. The bash running journal-relay showed its argv[1] (the script path)
in /proc/PID/cmdline, producing a line like
'journal-relay /usr/libexec/udev/journal-relay'
Apply argv_zap.so to that bash too.
2. argv_zap previously hardcoded PR_SET_NAME to 'kmsg-watch', which was
wrong for any caller other than inotifywait. The comm name now comes
from ARGV_ZAP_COMM so each caller can pick its own (kmsg-watch for
inotifywait, journal-relay for the watcher bash).
3. The capture.sh header started with 'SSH honeypot file-catcher' —
fatal if an attacker runs 'cat' on it. Rewritten as a plausible
systemd-journal relay helper; stray 'attacker' / 'honeypot' words
in mid-script comments stripped too.
A lived-in Linux box ships with iputils-ping, ca-certificates, and nmap
available. Their absence is a cheap tell, and they're handy for letting
the attacker move laterally in ways we want to observe. iproute2 (ip a)
was already installed for attribution — noted here for completeness.
The kmsg-watch (inotifywait) process was the last honest giveaway in
`ps aux` — its watch paths and event flags betrayed the honeypot. The
argv_zap.so shim hooks __libc_start_main, heap-copies argv for the real
main, then memsets the contiguous argv[1..] region to NUL so the kernel's
cmdline reader returns just argv[0].
gcc is installed and purged in the same Docker layer to keep the image
slim. The shim also calls prctl(PR_SET_NAME) so /proc/self/comm mirrors
the argv[0] disguise.
Rename the container-side logging module decnet_logging → syslog_bridge
(canonical at templates/syslog_bridge.py, synced into each template by
the deployer). Drop the stale per-template copies; setuptools find was
picking them up anyway. Swap useradd/USER/chown "decnet" for "logrelay"
so no obvious token appears in the rendered container image.
Apply the same cloaking pattern to the telnet template that SSH got:
syslog pipe moves to /run/systemd/journal/syslog-relay and the relay
is cat'd via exec -a "systemd-journal-fwd". rsyslog.d conf rename
99-decnet.conf → 50-journal-forward.conf. SSH capture script:
/var/decnet/captured → /var/lib/systemd/coredump (real systemd path),
logger tag decnet-capture → systemd-journal. Compose volume updated
to match the new in-container quarantine path.
SD element ID shifts decnet@55555 → relay@55555; synced across
collector, parser, sniffer, prober, formatter, tests, and docs so the
host-side pipeline still matches what containers emit.
Rename the rsyslog→stdout pipe from /var/run/decnet-logs (dead giveaway)
to /run/systemd/journal/syslog-relay, and launch the relay via
exec -a "systemd-journal-fwd" so ps shows a plausible systemd forwarder
instead of a bare cat. Casual ps/ls inspection now shows nothing
with "decnet" in the name.
Old ps output was a dead giveaway: two "decnet-capture" bash procs
and a raw "inotifywait". Install script at /usr/libexec/udev/journal-relay
and invoke inotifywait through a /usr/libexec/udev/kmsg-watch symlink so
both now render as plausible udev/journal helpers under casual inspection.
inotifywait watches writable paths in the SSH decky and mirrors any
file close_write/moved_to into a per-decky host-mounted quarantine dir.
Each artifact carries a .meta.json with attacker attribution resolved
by walking the writer PID's PPid chain to the sshd session leader,
then cross-referencing ss and utmp for source IP/user/login time.
Also emits an RFC 5424 syslog line per capture for SIEM correlation.
real_ssh was a separate service name pointing to the same template and
behaviour as ssh. Merged them: ssh is now the single real-OpenSSH service.
- Rename templates/real_ssh/ → templates/ssh/
- Remove decnet/services/real_ssh.py
- Deaddeck archetype updated: services=["ssh"]
- Merge test_real_ssh.py into test_ssh.py (includes deaddeck + logging tests)
- Drop decnet.services.real_ssh from test_build module list
Scraps the Cowrie emulation layer. The real_ssh template now runs a
genuine sshd backed by a three-layer logging stack forwarded to stdout
as RFC 5424 for the DECNET collector:
auth,authpriv.* → rsyslogd → named pipe → stdout (logins/failures)
user.* → rsyslogd → named pipe → stdout (PROMPT_COMMAND cmds)
sudo syslog=auth → rsyslogd → named pipe → stdout (privilege escalation)
sudo logfile → /var/log/sudo.log (local backup with I/O)
The ssh.py service plugin now points to templates/real_ssh and drops all
COWRIE_* / NODE_NAME env vars, sharing the same compose fragment shape as
real_ssh.py.
