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>
122 lines
3.9 KiB
Python
122 lines
3.9 KiB
Python
# SPDX-License-Identifier: GPL-3.0-or-later
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"""Runtime configuration.
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Defaults live here; overrides come from a TOML file (default
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``/etc/enodia-sentinel.toml``, or ``$ENODIA_CONFIG``) and a couple of env vars
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useful for testing without root (``$ENODIA_LOG_DIR``).
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"""
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from __future__ import annotations
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import os
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import tomllib
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from dataclasses import dataclass, field, fields
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from pathlib import Path
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_DEFAULT_INTERPRETERS = (
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"bash sh dash zsh ksh ash nc ncat netcat socat telnet "
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"python python2 python3 perl ruby php lua awk"
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).split()
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_DEFAULT_WATCH = (
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"/etc/cron.d", "/etc/crontab", "/etc/cron.daily", "/etc/cron.hourly",
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"/etc/cron.weekly", "/var/spool/cron", "/etc/systemd/system",
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"/etc/ld.so.preload", "/etc/passwd", "/etc/sudoers", "/etc/sudoers.d",
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"/root/.ssh/authorized_keys", "/root/.bashrc", "/root/.profile",
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)
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_ALL_DETECTORS = (
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"reverse_shell", "ld_preload", "deleted_exe",
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"new_listener", "new_suid", "persistence", "egress",
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)
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@dataclass
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class Config:
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# timing
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sample_interval: float = 4.0
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cooldown: int = 60
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baseline_grace: int = 10
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suid_refresh: int = 3600
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suid_scan_interval: int = 60
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# detector toggles
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detectors: frozenset[str] = frozenset(_ALL_DETECTORS)
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# tuning
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interpreters: frozenset[str] = frozenset(_DEFAULT_INTERPRETERS)
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egress_allow_cidrs: tuple[str, ...] = ()
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listener_allow_ports: frozenset[str] = frozenset()
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suid_hot_dirs: tuple[str, ...] = (
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"/tmp", "/dev/shm", "/var/tmp", "/home", "/run/user",
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)
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# Writable dirs always scanned for SUID even if on a separate filesystem
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# (tmpfs /tmp etc.). Kept small so the gated scan stays cheap.
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suid_scan_extra_dirs: tuple[str, ...] = (
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"/tmp", "/dev/shm", "/var/tmp", "/run/user",
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)
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watch_persistence: tuple[str, ...] = _DEFAULT_WATCH
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# eBPF on-ramp
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capture_execve_bpftrace: bool = False
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# Event-driven eBPF execve monitor (catches short-lived processes the poll
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# loop misses). Degrades gracefully to polling if bcc/root/BTF unavailable.
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ebpf_exec_monitor: bool = True
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exec_rules_file: str = "" # optional extra Snort-style rules (TOML)
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# retention
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max_snapshots: int = 300
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max_snapshot_age_days: int = 60
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# notifications
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notify_users: tuple[str, ...] = ()
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notify_urgency: str = "critical"
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# paths
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log_dir: Path = Path("/var/log/enodia-sentinel")
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# ---- derived paths ---------------------------------------------------
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@property
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def events_log(self) -> Path:
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return self.log_dir / "events.log"
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@property
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def listener_baseline(self) -> Path:
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return self.log_dir / "listener-baseline.json"
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@property
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def suid_baseline(self) -> Path:
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return self.log_dir / "suid-baseline.json"
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# ---- loading ---------------------------------------------------------
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@classmethod
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def load(cls, path: str | os.PathLike | None = None) -> "Config":
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cfg = cls()
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env_log = os.environ.get("ENODIA_LOG_DIR")
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if env_log:
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cfg.log_dir = Path(env_log)
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cfg_path = Path(path or os.environ.get("ENODIA_CONFIG")
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or "/etc/enodia-sentinel.toml")
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if cfg_path.is_file():
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cfg._apply_toml(cfg_path)
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return cfg
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def _apply_toml(self, path: Path) -> None:
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with open(path, "rb") as fh:
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data = tomllib.load(fh)
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known = {f.name for f in fields(self)}
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for key, value in data.items():
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if key not in known:
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continue
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current = getattr(self, key)
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if isinstance(current, frozenset):
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value = frozenset(value)
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elif isinstance(current, tuple):
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value = tuple(value)
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elif isinstance(current, Path):
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value = Path(value)
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setattr(self, key, value)
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def enabled(self, detector: str) -> bool:
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return detector in self.detectors
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