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).
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.
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.
inotify | while spawns a subshell for the tail of the pipeline, so
two bash processes (the script itself and the while-loop subshell)
showed up under /usr/libexec/udev/journal-relay in ps aux. Enable
lastpipe so the while loop runs in the main shell — ps now shows
one bash plus the inotify child, matching a simple udev helper.
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.
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.
fuser and /proc fd walks race scp/wget/sftp — by close_write the writer
has already closed the fd, so pid-chain attribution always resolved to
unknown for non-interactive drops. Fall back to the ss snapshot: one
established session → ss-only, multiple → ss-ambiguous (still record
src_ip from the first, analysts cross-check concurrent_sessions).
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.
