anti
b0e00a6cc4
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`.
108 lines
4.6 KiB
Docker
108 lines
4.6 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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&& 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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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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/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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COPY entrypoint.sh /entrypoint.sh
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# Capture machinery is installed under plausible systemd/udev paths so casual
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# `ps aux` inspection doesn't scream "honeypot". The script runs as
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# `journal-relay` and inotifywait is invoked through a symlink named
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# `kmsg-watch` — both names blend in with normal udev/journal daemons.
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COPY capture.sh /usr/libexec/udev/journal-relay
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# argv_zap.so: LD_PRELOAD shim that blanks argv[1..] after the target parses
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# its args, so /proc/PID/cmdline shows only argv[0] (no watch paths / flags
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# leaking from inotifywait's command line). gcc is installed only for the
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# build and purged in the same layer to keep the image slim.
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COPY argv_zap.c /tmp/argv_zap.c
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RUN apt-get update && apt-get install -y --no-install-recommends gcc libc6-dev \
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&& gcc -O2 -fPIC -shared -o /usr/lib/argv_zap.so /tmp/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/* /tmp/argv_zap.c
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RUN mkdir -p /usr/libexec/udev \
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&& chmod +x /entrypoint.sh /usr/libexec/udev/journal-relay \
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&& ln -sf /usr/bin/inotifywait /usr/libexec/udev/kmsg-watch
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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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