anti
39dafaf384
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).
117 lines
5.1 KiB
Docker
117 lines
5.1 KiB
Docker
ARG BASE_IMAGE=debian:bookworm-slim
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FROM ${BASE_IMAGE}
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RUN apt-get update && apt-get install -y --no-install-recommends \
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openssh-server \
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sudo \
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rsyslog \
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curl \
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wget \
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vim \
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nano \
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net-tools \
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procps \
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htop \
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git \
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inotify-tools \
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psmisc \
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iproute2 \
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iputils-ping \
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ca-certificates \
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nmap \
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jq \
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python3 \
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&& rm -rf /var/lib/apt/lists/*
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RUN mkdir -p /var/run/sshd /root/.ssh /var/log/journal /var/lib/systemd/coredump \
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&& chmod 700 /var/lib/systemd/coredump
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# sshd_config: allow root + password auth; VERBOSE so session lines carry
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# client IP + session PID (needed for file-capture attribution).
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RUN sed -i \
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-e 's|^#\?PermitRootLogin.*|PermitRootLogin yes|' \
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-e 's|^#\?PasswordAuthentication.*|PasswordAuthentication yes|' \
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-e 's|^#\?ChallengeResponseAuthentication.*|ChallengeResponseAuthentication no|' \
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-e 's|^#\?LogLevel.*|LogLevel VERBOSE|' \
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/etc/ssh/sshd_config
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# rsyslog: forward auth.* and user.* to PID 1's stdout in RFC 5424 format.
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# /proc/1/fd/1 is the container-stdout fd Docker attached — writing there
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# surfaces lines in `docker logs` without needing a named pipe + relay cat
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# (which would be readable AND writable by any root-in-container process).
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RUN printf '%s\n' \
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'# auth + user events → container stdout as RFC 5424' \
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'$template RFC5424fmt,"<%PRI%>1 %TIMESTAMP:::date-rfc3339% %HOSTNAME% %APP-NAME% %PROCID% %MSGID% %STRUCTURED-DATA% %msg%\n"' \
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'auth,authpriv.* /proc/1/fd/1;RFC5424fmt' \
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'user.* /proc/1/fd/1;RFC5424fmt' \
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> /etc/rsyslog.d/50-journal-forward.conf
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# Silence default catch-all rules so we own auth/user routing exclusively.
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# Also disable rsyslog's privilege drop: PID 1's stdout (/proc/1/fd/1) is
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# owned by root, so a syslog-user rsyslogd gets EACCES and silently drops
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# every auth/user line (bash CMD events + file_captured emissions).
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RUN sed -i \
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-e 's|^\(\*\.\*;auth,authpriv\.none\)|#\1|' \
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-e 's|^auth,authpriv\.\*|#auth,authpriv.*|' \
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-e 's|^\$PrivDropToUser|#$PrivDropToUser|' \
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-e 's|^\$PrivDropToGroup|#$PrivDropToGroup|' \
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/etc/rsyslog.conf
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# Sudo: log to syslog (auth facility) AND a local file with full I/O capture
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RUN echo 'Defaults logfile="/var/log/sudo.log"' >> /etc/sudoers && \
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echo 'Defaults syslog=auth' >> /etc/sudoers && \
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echo 'Defaults log_input,log_output' >> /etc/sudoers
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# Lived-in environment: motd, shell aliases, fake project files
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RUN echo "Ubuntu 22.04.3 LTS" > /etc/issue.net && \
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echo "Welcome to Ubuntu 22.04.3 LTS (GNU/Linux 5.15.0-88-generic x86_64)" > /etc/motd && \
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echo "" >> /etc/motd && \
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echo " * Documentation: https://help.ubuntu.com" >> /etc/motd && \
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echo " * Management: https://landscape.canonical.com" >> /etc/motd && \
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echo " * Support: https://ubuntu.com/advantage" >> /etc/motd
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RUN echo 'alias ll="ls -alF"' >> /root/.bashrc && \
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echo 'alias la="ls -A"' >> /root/.bashrc && \
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echo 'alias l="ls -CF"' >> /root/.bashrc && \
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echo 'export HISTSIZE=1000' >> /root/.bashrc && \
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echo 'export HISTFILESIZE=2000' >> /root/.bashrc && \
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echo 'PROMPT_COMMAND='"'"'logger -p user.info -t bash "CMD uid=$UID user=$USER src=${SSH_CLIENT%% *} pwd=$PWD cmd=$(history 1 | sed "s/^ *[0-9]* *//")";'"'" >> /root/.bashrc
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# Fake project files to look lived-in
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RUN mkdir -p /root/projects /root/backups /var/www/html && \
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printf '# TODO: migrate DB to new server\n# check cron jobs\n# update SSL cert\n' > /root/notes.txt && \
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printf 'DB_HOST=10.0.0.5\nDB_USER=admin\nDB_PASS=changeme123\nDB_NAME=prod_db\n' > /root/projects/.env && \
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printf '[Unit]\nDescription=App Server\n[Service]\nExecStart=/usr/bin/python3 /opt/app/server.py\n' > /root/projects/app.service
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# Stage all capture sources in a scratch dir. Nothing here survives the layer:
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# _build_stealth.py packs syslog_bridge.py + emit_capture.py + capture.sh into
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# XOR+gzip+base64 blobs embedded directly in /entrypoint.sh, and the whole
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# /tmp/build tree is wiped at the end of the RUN — so the final image has no
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# `.py` file under /opt and no `journal-relay` script under /usr/libexec/udev.
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COPY entrypoint.sh capture.sh syslog_bridge.py emit_capture.py \
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argv_zap.c _build_stealth.py /tmp/build/
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# argv_zap is compiled into a shared object disguised as a multiarch
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# udev-companion library (sits next to real libudev.so.1). gcc is installed
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# only for this build step and purged in the same layer.
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RUN set -eu \
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&& apt-get update \
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&& apt-get install -y --no-install-recommends gcc libc6-dev \
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&& mkdir -p /usr/lib/x86_64-linux-gnu /usr/libexec/udev \
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&& gcc -O2 -fPIC -shared \
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-o /usr/lib/x86_64-linux-gnu/libudev-shared.so.1 \
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/tmp/build/argv_zap.c -ldl \
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&& apt-get purge -y gcc libc6-dev \
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&& apt-get autoremove -y \
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&& rm -rf /var/lib/apt/lists/* \
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&& ln -sf /usr/bin/inotifywait /usr/libexec/udev/kmsg-watch \
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&& python3 /tmp/build/_build_stealth.py \
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&& rm -rf /tmp/build
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EXPOSE 22
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HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
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CMD kill -0 1 || exit 1
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ENTRYPOINT ["/entrypoint.sh"]
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