Merge pull request #370 from Nomadu27/feat/insaits-security-hook

feat: add InsAIts PostToolUse security monitoring hook
This commit is contained in:
Affaan Mustafa
2026-03-10 20:51:09 -07:00
committed by GitHub
6 changed files with 414 additions and 0 deletions

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@@ -25,6 +25,7 @@ User request → Claude picks a tool → PreToolUse hook runs → Tool executes
| **Git push reminder** | `Bash` | Reminds to review changes before `git push` | 0 (warns) |
| **Doc file warning** | `Write` | Warns about non-standard `.md`/`.txt` files (allows README, CLAUDE, CONTRIBUTING, CHANGELOG, LICENSE, SKILL, docs/, skills/); cross-platform path handling | 0 (warns) |
| **Strategic compact** | `Edit\|Write` | Suggests manual `/compact` at logical intervals (every ~50 tool calls) | 0 (warns) |
| **InsAIts security monitor (opt-in)** | `Bash\|Write\|Edit\|MultiEdit` | Optional security scan for high-signal tool inputs. Disabled unless `ECC_ENABLE_INSAITS=1`. Blocks on critical findings, warns on non-critical, and writes audit log to `.insaits_audit_session.jsonl`. Requires `pip install insa-its`. [Details](../scripts/hooks/insaits-security-monitor.py) | 2 (blocks critical) / 0 (warns) |
### PostToolUse Hooks

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@@ -63,6 +63,17 @@
}
],
"description": "Capture tool use observations for continuous learning"
},
{
"matcher": "Bash|Write|Edit|MultiEdit",
"hooks": [
{
"type": "command",
"command": "node \"${CLAUDE_PLUGIN_ROOT}/scripts/hooks/run-with-flags.js\" \"pre:insaits-security\" \"scripts/hooks/insaits-security-wrapper.js\" \"standard,strict\"",
"timeout": 15
}
],
"description": "Optional InsAIts AI security monitor for Bash/Edit/Write flows. Enable with ECC_ENABLE_INSAITS=1. Requires: pip install insa-its"
}
],
"PreCompact": [

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@@ -88,6 +88,11 @@
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/your/projects"],
"description": "Filesystem operations (set your path)"
},
"insaits": {
"command": "python3",
"args": ["-m", "insa_its.mcp_server"],
"description": "AI-to-AI security monitoring — anomaly detection, credential exposure, hallucination checks, forensic tracing. 23 anomaly types, OWASP MCP Top 10 coverage. 100% local. Install: pip install insa-its"
}
},
"_comments": {

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@@ -0,0 +1,269 @@
#!/usr/bin/env python3
"""
InsAIts Security Monitor -- PreToolUse Hook for Claude Code
============================================================
Real-time security monitoring for Claude Code tool inputs.
Detects credential exposure, prompt injection, behavioral anomalies,
hallucination chains, and 20+ other anomaly types -- runs 100% locally.
Writes audit events to .insaits_audit_session.jsonl for forensic tracing.
Setup:
pip install insa-its
export ECC_ENABLE_INSAITS=1
Add to .claude/settings.json:
{
"hooks": {
"PreToolUse": [
{
"matcher": "Bash|Write|Edit|MultiEdit",
"hooks": [
{
"type": "command",
"command": "node scripts/hooks/insaits-security-wrapper.js"
}
]
}
]
}
}
How it works:
Claude Code passes tool input as JSON on stdin.
This script runs InsAIts anomaly detection on the content.
Exit code 0 = clean (pass through).
Exit code 2 = critical issue found (blocks tool execution).
Stderr output = non-blocking warning shown to Claude.
Environment variables:
INSAITS_DEV_MODE Set to "true" to enable dev mode (no API key needed).
Defaults to "false" (strict mode).
INSAITS_MODEL LLM model identifier for fingerprinting. Default: claude-opus.
INSAITS_FAIL_MODE "open" (default) = continue on SDK errors.
"closed" = block tool execution on SDK errors.
INSAITS_VERBOSE Set to any value to enable debug logging.
Detections include:
- Credential exposure (API keys, tokens, passwords)
- Prompt injection patterns
- Hallucination indicators (phantom citations, fact contradictions)
- Behavioral anomalies (context loss, semantic drift)
- Tool description divergence
- Shorthand emergence / jargon drift
All processing is local -- no data leaves your machine.
Author: Cristi Bogdan -- YuyAI (https://github.com/Nomadu27/InsAIts)
License: Apache 2.0
"""
from __future__ import annotations
import hashlib
import json
import logging
import os
import sys
import time
from typing import Any, Dict, List, Tuple
# Configure logging to stderr so it does not interfere with stdout protocol
logging.basicConfig(
stream=sys.stderr,
format="[InsAIts] %(message)s",
level=logging.DEBUG if os.environ.get("INSAITS_VERBOSE") else logging.WARNING,
)
log = logging.getLogger("insaits-hook")
# Try importing InsAIts SDK
try:
from insa_its import insAItsMonitor
INSAITS_AVAILABLE: bool = True
except ImportError:
INSAITS_AVAILABLE = False
# --- Constants ---
AUDIT_FILE: str = ".insaits_audit_session.jsonl"
MIN_CONTENT_LENGTH: int = 10
MAX_SCAN_LENGTH: int = 4000
DEFAULT_MODEL: str = "claude-opus"
BLOCKING_SEVERITIES: frozenset = frozenset({"CRITICAL"})
def extract_content(data: Dict[str, Any]) -> Tuple[str, str]:
"""Extract inspectable text from a Claude Code tool input payload.
Returns:
A (text, context) tuple where *text* is the content to scan and
*context* is a short label for the audit log.
"""
tool_name: str = data.get("tool_name", "")
tool_input: Dict[str, Any] = data.get("tool_input", {})
text: str = ""
context: str = ""
if tool_name in ("Write", "Edit", "MultiEdit"):
text = tool_input.get("content", "") or tool_input.get("new_string", "")
context = "file:" + str(tool_input.get("file_path", ""))[:80]
elif tool_name == "Bash":
# PreToolUse: the tool hasn't executed yet, inspect the command
command: str = str(tool_input.get("command", ""))
text = command
context = "bash:" + command[:80]
elif "content" in data:
content: Any = data["content"]
if isinstance(content, list):
text = "\n".join(
b.get("text", "") for b in content if b.get("type") == "text"
)
elif isinstance(content, str):
text = content
context = str(data.get("task", ""))
return text, context
def write_audit(event: Dict[str, Any]) -> None:
"""Append an audit event to the JSONL audit log.
Creates a new dict to avoid mutating the caller's *event*.
"""
try:
enriched: Dict[str, Any] = {
**event,
"timestamp": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
}
enriched["hash"] = hashlib.sha256(
json.dumps(enriched, sort_keys=True).encode()
).hexdigest()[:16]
with open(AUDIT_FILE, "a", encoding="utf-8") as f:
f.write(json.dumps(enriched) + "\n")
except OSError as exc:
log.warning("Failed to write audit log %s: %s", AUDIT_FILE, exc)
def get_anomaly_attr(anomaly: Any, key: str, default: str = "") -> str:
"""Get a field from an anomaly that may be a dict or an object.
The SDK's ``send_message()`` returns anomalies as dicts, while
other code paths may return dataclass/object instances. This
helper handles both transparently.
"""
if isinstance(anomaly, dict):
return str(anomaly.get(key, default))
return str(getattr(anomaly, key, default))
def format_feedback(anomalies: List[Any]) -> str:
"""Format detected anomalies as feedback for Claude Code.
Returns:
A human-readable multi-line string describing each finding.
"""
lines: List[str] = [
"== InsAIts Security Monitor -- Issues Detected ==",
"",
]
for i, a in enumerate(anomalies, 1):
sev: str = get_anomaly_attr(a, "severity", "MEDIUM")
atype: str = get_anomaly_attr(a, "type", "UNKNOWN")
detail: str = get_anomaly_attr(a, "details", "")
lines.extend([
f"{i}. [{sev}] {atype}",
f" {detail[:120]}",
"",
])
lines.extend([
"-" * 56,
"Fix the issues above before continuing.",
"Audit log: " + AUDIT_FILE,
])
return "\n".join(lines)
def main() -> None:
"""Entry point for the Claude Code PreToolUse hook."""
raw: str = sys.stdin.read().strip()
if not raw:
sys.exit(0)
try:
data: Dict[str, Any] = json.loads(raw)
except json.JSONDecodeError:
data = {"content": raw}
text, context = extract_content(data)
# Skip very short content (e.g. "OK", empty bash results)
if len(text.strip()) < MIN_CONTENT_LENGTH:
sys.exit(0)
if not INSAITS_AVAILABLE:
log.warning("Not installed. Run: pip install insa-its")
sys.exit(0)
# Wrap SDK calls so an internal error does not crash the hook
try:
monitor: insAItsMonitor = insAItsMonitor(
session_name="claude-code-hook",
dev_mode=os.environ.get(
"INSAITS_DEV_MODE", "false"
).lower() in ("1", "true", "yes"),
)
result: Dict[str, Any] = monitor.send_message(
text=text[:MAX_SCAN_LENGTH],
sender_id="claude-code",
llm_id=os.environ.get("INSAITS_MODEL", DEFAULT_MODEL),
)
except Exception as exc: # Broad catch intentional: unknown SDK internals
fail_mode: str = os.environ.get("INSAITS_FAIL_MODE", "open").lower()
if fail_mode == "closed":
sys.stdout.write(
f"InsAIts SDK error ({type(exc).__name__}); "
"blocking execution to avoid unscanned input.\n"
)
sys.exit(2)
log.warning(
"SDK error (%s), skipping security scan: %s",
type(exc).__name__, exc,
)
sys.exit(0)
anomalies: List[Any] = result.get("anomalies", [])
# Write audit event regardless of findings
write_audit({
"tool": data.get("tool_name", "unknown"),
"context": context,
"anomaly_count": len(anomalies),
"anomaly_types": [get_anomaly_attr(a, "type") for a in anomalies],
"text_length": len(text),
})
if not anomalies:
log.debug("Clean -- no anomalies detected.")
sys.exit(0)
# Determine maximum severity
has_critical: bool = any(
get_anomaly_attr(a, "severity").upper() in BLOCKING_SEVERITIES
for a in anomalies
)
feedback: str = format_feedback(anomalies)
if has_critical:
# stdout feedback -> Claude Code shows to the model
sys.stdout.write(feedback + "\n")
sys.exit(2) # PreToolUse exit 2 = block tool execution
else:
# Non-critical: warn via stderr (non-blocking)
log.warning("\n%s", feedback)
sys.exit(0)
if __name__ == "__main__":
main()

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@@ -0,0 +1,88 @@
#!/usr/bin/env node
/**
* InsAIts Security Monitor — wrapper for run-with-flags compatibility.
*
* This thin wrapper receives stdin from the hooks infrastructure and
* delegates to the Python-based insaits-security-monitor.py script.
*
* The wrapper exists because run-with-flags.js spawns child scripts
* via `node`, so a JS entry point is needed to bridge to Python.
*/
'use strict';
const path = require('path');
const { spawnSync } = require('child_process');
const MAX_STDIN = 1024 * 1024;
function isEnabled(value) {
return ['1', 'true', 'yes', 'on'].includes(String(value || '').toLowerCase());
}
let raw = '';
process.stdin.setEncoding('utf8');
process.stdin.on('data', chunk => {
if (raw.length < MAX_STDIN) {
raw += chunk.substring(0, MAX_STDIN - raw.length);
}
});
process.stdin.on('end', () => {
if (!isEnabled(process.env.ECC_ENABLE_INSAITS)) {
process.stdout.write(raw);
process.exit(0);
}
const scriptDir = __dirname;
const pyScript = path.join(scriptDir, 'insaits-security-monitor.py');
// Try python3 first (macOS/Linux), fall back to python (Windows)
const pythonCandidates = ['python3', 'python'];
let result;
for (const pythonBin of pythonCandidates) {
result = spawnSync(pythonBin, [pyScript], {
input: raw,
encoding: 'utf8',
env: process.env,
cwd: process.cwd(),
timeout: 14000,
});
// ENOENT means binary not found — try next candidate
if (result.error && result.error.code === 'ENOENT') {
continue;
}
break;
}
if (!result || (result.error && result.error.code === 'ENOENT')) {
process.stderr.write('[InsAIts] python3/python not found. Install Python 3.9+ and: pip install insa-its\n');
process.stdout.write(raw);
process.exit(0);
}
// Log non-ENOENT spawn errors (timeout, signal kill, etc.) so users
// know the security monitor did not run — fail-open with a warning.
if (result.error) {
process.stderr.write(`[InsAIts] Security monitor failed to run: ${result.error.message}\n`);
process.stdout.write(raw);
process.exit(0);
}
// result.status is null when the process was killed by a signal or
// timed out. Check BEFORE writing stdout to avoid leaking partial
// or corrupt monitor output. Pass through original raw input instead.
if (!Number.isInteger(result.status)) {
const signal = result.signal || 'unknown';
process.stderr.write(`[InsAIts] Security monitor killed (signal: ${signal}). Tool execution continues.\n`);
process.stdout.write(raw);
process.exit(0);
}
if (result.stdout) process.stdout.write(result.stdout);
if (result.stderr) process.stderr.write(result.stderr);
process.exit(result.status);
});

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@@ -290,6 +290,28 @@ async function runTests() {
passed++;
else failed++;
// insaits-security-wrapper.js tests
console.log('\ninsaits-security-wrapper.js:');
if (
await asyncTest('passes through input unchanged when integration is disabled', async () => {
const stdinData = JSON.stringify({
tool_name: 'Write',
tool_input: { file_path: 'src/index.ts', content: 'console.log("ok");' }
});
const result = await runScript(
path.join(scriptsDir, 'insaits-security-wrapper.js'),
stdinData,
{ ECC_ENABLE_INSAITS: '' }
);
assert.strictEqual(result.code, 0, `Exit code should be 0, got ${result.code}`);
assert.strictEqual(result.stdout, stdinData, 'Should pass stdin through unchanged');
assert.strictEqual(result.stderr, '', 'Should stay silent when integration is disabled');
})
)
passed++;
else failed++;
// check-console-log.js tests
console.log('\ncheck-console-log.js:');
@@ -1649,6 +1671,24 @@ async function runTests() {
passed++;
else failed++;
if (
test('InsAIts hook is opt-in and scoped to high-signal tool inputs', () => {
const hooksPath = path.join(__dirname, '..', '..', 'hooks', 'hooks.json');
const hooks = JSON.parse(fs.readFileSync(hooksPath, 'utf8'));
const insaitsHook = hooks.hooks.PreToolUse.find(entry => entry.description && entry.description.includes('InsAIts'));
assert.ok(insaitsHook, 'Should define an InsAIts PreToolUse hook');
assert.strictEqual(insaitsHook.matcher, 'Bash|Write|Edit|MultiEdit', 'InsAIts hook should avoid matching every tool');
assert.ok(insaitsHook.description.includes('ECC_ENABLE_INSAITS=1'), 'InsAIts hook should document explicit opt-in');
assert.ok(
insaitsHook.hooks[0].command.includes('insaits-security-wrapper.js'),
'InsAIts hook should execute through the JS wrapper'
);
})
)
passed++;
else failed++;
// plugin.json validation
console.log('\nplugin.json Validation:');