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>
45 lines
1.4 KiB
Python
45 lines
1.4 KiB
Python
# SPDX-License-Identifier: GPL-3.0-or-later
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"""persistence — modification of a watched persistence-relevant file.
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Persistence has to land somewhere that survives a reboot: cron, systemd units,
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``authorized_keys``, shell rc files. We watch a configurable set and alert on
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anything modified since the previous scan (``state.persist_since``).
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"""
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from __future__ import annotations
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import os
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from collections.abc import Iterator
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from ..alert import Alert, Severity
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from ..config import Config
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from ..system import SystemState
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def _iter_files(roots) -> Iterator[str]:
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for root in roots:
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if os.path.isdir(root):
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for dirpath, _dirs, files in os.walk(root, onerror=lambda e: None):
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for f in files:
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yield os.path.join(dirpath, f)
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elif os.path.lexists(root):
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yield root
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def detect(state: SystemState, cfg: Config) -> Iterator[Alert]:
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since = state.persist_since
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if since is None:
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return
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for path in _iter_files(cfg.watch_persistence):
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try:
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mtime = os.lstat(path).st_mtime
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except OSError:
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continue
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if mtime > since:
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yield Alert(
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severity=Severity.HIGH,
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signature="persistence",
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key=f"persist:{path}",
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detail=f"persistence file modified: {path}",
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sid=100015,
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classtype="persistence",
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)
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