0eb5077551
Closes polling's blind spot (processes that exit between sweeps) with a real
eBPF probe and a declarative, data-driven detection engine — inspired by Snort
(rule language, signature IDs) and OSSEC (host-IDS framing).
New events/ subpackage:
- bcc_source.py : eBPF C tracing execve (filename, argv[1..2], ppid, uid,
parent comm) over a perf buffer, loaded via bcc; lazy import
+ available()/try-except so it fails closed to poll-only when
bcc/root/BTF are absent — a broken probe never downs the daemon
- exec_event.py : the ExecEvent type
- rules.py : ExecRule (sid/msg/severity/classtype + path/exec/parent/argv
conditions) and ExecRuleEngine; 4 shipped rules (fileless exec
100001, reverse-shell argv 100002, web/DB→shell RCE 100003,
curl|sh 100004); operators add more via exec_rules_file TOML
- monitor.py : runs the source on a thread, routes events through the engine
Integration:
- daemon starts the monitor, shares a lock-guarded cooldown with the sweep
loop, and feeds event alerts into the same snapshot pipeline
- Alert gains Snort-style sid + classtype; retrofitted onto all 7 poll
detectors; snapshots and JSON now carry them
- config: ebpf_exec_monitor (default on, degrades), exec_rules_file
- systemd: opt-in ebpf.conf drop-in (relaxes MemoryDenyWriteExecute + widens
caps for bcc's JIT) so the base unit stays hardened for poll-only
- sentinel-redteam: ebpf_exec drill (short-lived /tmp exec + /dev/tcp argv the
poller can't see); footer now uses the Python CLI
Tests: +14 cases for the rule engine (each default rule match/non-match, rule
validation, parent-exclude). 39/39 pass. Graceful non-root degradation verified.
NOTE: the eBPF C follows bcc's execsnoop pattern but could not be run here
(BPF needs root); it wants a root smoke-test on a real host.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
55 lines
1.8 KiB
Python
55 lines
1.8 KiB
Python
# SPDX-License-Identifier: GPL-3.0-or-later
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"""Runs the eBPF exec source on a thread and routes events through the engine."""
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from __future__ import annotations
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import threading
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from collections.abc import Callable
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from ..alert import Alert
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from ..config import Config
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from . import bcc_source
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from .exec_event import ExecEvent
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from .rules import ExecRuleEngine
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class ExecMonitor:
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"""Owns the event source + rule engine; emits Alerts via ``on_alert``.
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``start()`` is best-effort: it returns a (started, reason) pair and never
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raises, so the daemon can log the reason and carry on with polling.
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"""
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def __init__(self, cfg: Config, on_alert: Callable[[Alert], None]) -> None:
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self.cfg = cfg
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self._on_alert = on_alert
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self.engine = ExecRuleEngine.load(cfg.exec_rules_file)
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self._source = bcc_source.BccExecSource(self._on_event)
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self._thread: threading.Thread | None = None
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self._stop = threading.Event()
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def start(self) -> tuple[bool, str]:
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ok, reason = bcc_source.available()
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if not ok:
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return False, reason
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try:
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self._source.start()
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except Exception as exc: # compilation/attach/permission failure
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return False, f"probe load failed: {exc!r}"
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self._thread = threading.Thread(target=self._run, daemon=True)
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self._thread.start()
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return True, "ok"
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def _run(self) -> None:
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while not self._stop.is_set():
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try:
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self._source.poll(timeout_ms=200)
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except Exception:
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break
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def _on_event(self, ev: ExecEvent) -> None:
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for alert in self.engine.match(ev):
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self._on_alert(alert)
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def stop(self) -> None:
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self._stop.set()
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self._source.stop()
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