claude
389ac2e460
Apply the no-ai-slop standard (now binding in AGENTS.md): the em-dash character is banned outright (restructured, not blind-replaced), plus the banned word/phrase list (delve, leverage, robust, seamless, truly, unlock, etc.). 0 em-dashes remain in modules + capstone; the only "robust" left is the planted M10 ai-change.patch trap. Module H1 titles use a colon separator. All deliberate teaching devices preserved; labs compile/parse (py/sh/yaml/json); no junk. AGENTS.md updated with the hard no-slop rules. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TfzV5QvtPDz8LJS3Pu5VLT
98 lines
4.1 KiB
Bash
Executable File
98 lines
4.1 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Module 19 lab: what a CI job could see if it ran on THIS machine.
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#
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# Run this on any machine you'd consider turning into a self-hosted runner (your laptop is fine for
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# the exercise). It does NOT change anything; it only LOOKS. The point is to make concrete what is
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# otherwise abstract: a "workflow step" is just a shell command, so whatever this read-only script
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# can see, a malicious workflow step (e.g. from a pull request) running on this runner can see too.
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#
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# bash inspect-runner.sh
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#
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# Then paste the output into your AI and ask it to rank, worst-first, what a malicious PR could
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# steal or reach if this were your runner. That conversation IS the security tradeoff for this module.
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set -u
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line() { printf '\n=== %s ===\n' "$1"; }
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# Try a TCP connect to host:port with a ~2s deadline, portably.
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# GNU `timeout` (Linux) or Homebrew's `gtimeout` are used when present; otherwise a bash-native
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# background-and-kill fallback keeps this working on stock macOS, which ships no GNU `timeout`.
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tcp_probe() {
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host="$1"; port="$2"
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if command -v timeout >/dev/null 2>&1; then
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timeout 2 bash -c ">/dev/tcp/${host}/${port}" 2>/dev/null
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elif command -v gtimeout >/dev/null 2>&1; then
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gtimeout 2 bash -c ">/dev/tcp/${host}/${port}" 2>/dev/null
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else
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bash -c ">/dev/tcp/${host}/${port}" 2>/dev/null &
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probe_pid=$!
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( sleep 2; kill "$probe_pid" 2>/dev/null ) >/dev/null 2>&1 &
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killer_pid=$!
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rc=0; wait "$probe_pid" 2>/dev/null || rc=$?
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kill "$killer_pid" 2>/dev/null
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return "$rc"
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fi
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}
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line "WHO AND WHERE"
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echo "hostname : $(hostname 2>/dev/null)"
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echo "user : $(whoami 2>/dev/null) (root? $( [ "$(id -u 2>/dev/null)" = 0 ] && echo YES || echo no ))"
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echo "os : $(uname -srm 2>/dev/null)"
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echo " >> A runner should run as a dedicated low-privilege user, never root, never your login."
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line "SECRETS SITTING IN THE ENVIRONMENT"
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# Don't print values, just the names. Seeing the NAMES is enough to make the point.
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env | grep -iE 'token|secret|key|password|passwd|credential|aws|gcp|azure|api' | cut -d= -f1 | sort -u \
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| sed 's/^/ exposed env var: /' || true
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echo " >> Any of these is readable by every job step. Scope runner secrets to the absolute minimum."
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line "CREDENTIAL FILES ON DISK"
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for p in \
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"$HOME/.aws/credentials" \
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"$HOME/.config/gcloud" \
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"$HOME/.azure" \
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"$HOME/.docker/config.json" \
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"$HOME/.kube/config" \
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"$HOME/.netrc" \
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"$HOME/.git-credentials" ; do
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[ -e "$p" ] && echo " FOUND: $p"
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done
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echo " (nothing listed above = none of those common credential stores are present here)"
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line "SSH KEYS (pivot material)"
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if [ -d "$HOME/.ssh" ]; then
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ls -1 "$HOME/.ssh" 2>/dev/null | sed 's/^/ ~\/.ssh\//'
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echo " >> Private keys here let a compromised job hop to every host you can SSH to."
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else
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echo " no ~/.ssh directory"
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fi
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line "DOCKER SOCKET (root-equivalent if present)"
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if [ -S /var/run/docker.sock ]; then
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echo " /var/run/docker.sock EXISTS and is reachable."
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echo " >> Access to the Docker socket is effectively root on the host. Big deal."
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else
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echo " no reachable docker socket"
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fi
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line "PRIVATE NETWORK REACH (the reason you self-host, and the reason it's dangerous)"
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# Probe a few common private ranges' gateways and any hosts you care about.
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# Edit these to match your network for a sharper result.
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PROBES=( "192.168.0.1:80" "192.168.1.1:80" "10.0.0.1:80" )
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for hp in "${PROBES[@]}"; do
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host="${hp%%:*}"; port="${hp##*:}"
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if tcp_probe "$host" "$port"; then
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echo " REACHABLE: ${host}:${port}"
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fi
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done
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echo " (edit the PROBES list above to test your real internal hosts: databases, deploy targets)"
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echo " >> Every reachable internal host is something a compromised runner can attack or exfiltrate."
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line "BOTTOM LINE"
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echo "Everything listed above is what a self-hosted runner on this box would hand to ANY job it runs,"
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echo "including a job defined by a pull request you haven't merged. That is the tradeoff. Mitigate with:"
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echo " - ephemeral runners (fresh environment per job)"
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echo " - a dedicated low-priv user on an isolated network segment"
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echo " - least-privilege secrets, and NEVER attach this to a public repo without fork-PR approval"
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