Sentinel — Agent Security Layer

Runtime security layer for OpenClaw agents. Intercepts and scans all external input (emails, API responses, web content, chat messages, calendar events) for...

Security Scan

The skill's files, instructions, and requested resources are consistent with a local runtime input/output security filter — it operates as a set of bash filters that read stdin, write logs under ~/.sentinel, and can inject/check canary tokens; nothing in the package requests unrelated credentials, network access, or hidden installers.

Purpose & Capability

The name/description (runtime input/output sentinel) matches the provided artifacts: multiple bash scripts that scan stdin, log threats to ~/.sentinel/threats.jsonl, generate/check canaries, and optionally use a premium patterns file. No unexplained environment variables, binaries, or cloud credentials are required.

Instruction Scope

SKILL.md and scripts stay within the stated purpose (intercept/scan inputs and monitor outputs). Noteworthy: the guide explicitly instructs adding invisible canary markers into SOUL.md or system prompts and recommends piping all external content through the filters — these are expected for a runtime sentinel but do instruct modifying local agent files (SOUL.md/system prompt), so users should review and back up any files before injecting markers.

Install Mechanism

No install spec; this is instruction-plus-scripts (pure bash). No downloads or remote installers are invoked by the package. The scripts rely on common utilities (grep, sed, base64, optionally jq).

Credentials

The skill asks for no credentials or env vars. The scripts scan for many secret/token formats (OpenAI, AWS, GitHub, crypto keys, etc.), which is coherent with its stated goal. The premium pack path (~/.sentinel/premium_patterns.json) and optional use of jq are documented and proportional.

Persistence & Privilege

The scripts create and write logs under ~/.sentinel and can inject canary markers into user-specified files. always:false and autonomous invocation defaults are unchanged. Writing to user files and creating ~/.sentinel is expected for the tool's purpose but is a permanent local change the user should consent to.

Scan Findings in Context

[system-prompt-override] expected: The SKILL.md and patterns intentionally include prompt-injection phrases (system prompt override patterns) because the tool's function is to detect such injections. The pre-scan detector flagged this content but it's appropriate for a sentinel.

Assessment

This skill is a set of local bash filters that scan stdin and stdout for injections and secrets and stores logs under ~/.sentinel. Before installing/using: (1) review and test the scripts on non-sensitive sample data; (2) be aware the canary tool can modify files you point it at (e.g., SOUL.md or other prompts) — back up those files first; (3) the premium rules require jq and an optional premium_patterns.json file (if absent the premium check is a no-op); (4) expect false positives (hex strings or common words may trigger crypto/secret heuristics) — tune thresholds/patterns in ~/.sentinel/config.sh or by editing the patterns; (5) there are no hidden network calls in the provided scripts, but always inspect any third-party premium patterns before placing them in ~/.sentinel. If you need the sentinel to be enforced platform-wide, note that this package does not automatically force inclusion — you must integrate the scripts into your agent pipeline yourself.

🛡️ Claw Sentinel — Runtime Security Layer for OpenClaw

Why This Exists

ClawDefender, ClawSec, Skill Defender — all check skills before you install them.

Nobody checks what happens AFTER installation, at runtime.

Your agent reads emails, parses API responses, fetches web pages — any of these can carry hidden prompt injection. Claw Sentinel sits between external data and your agent, scanning everything in real-time.

What makes it different from ClawDefender?

Feature	ClawDefender	Claw Sentinel
Pre-install skill scanning	✅	❌ (use ClawDefender for that)
Automatic input interception	❌	✅
Output monitoring (secret leak)	❌	✅
Multi-language injection detection	❌	✅ (EN/RU/ZH/ES/AR/KO/JA)
Unicode/encoding normalization	❌	✅
Canary token leak detection	❌	✅
Crypto wallet/key specific patterns	❌	✅
Severity scoring	✅	✅

Quick Start

cp skills/claw-sentinel/scripts/*.sh scripts/
cp skills/claw-sentinel/patterns/*.json patterns/
chmod +x scripts/sentinel-*.sh

# Test
echo "sample_input.txt" | scripts/sentinel-input.sh
# 🔴 CRITICAL [prompt_injection + data_exfil]: 2 threats detected

Architecture

External Data ──▶ sentinel-input.sh ──▶ Clean data ──▶ Agent
                        │
                        ▼ (threat found)
                  sentinel-log.sh ──▶ ~/.sentinel/threats.jsonl

Agent output ──▶ sentinel-output.sh ──▶ Safe response ──▶ User

Usage

Input Guard

curl -s "https://api.example.com/data" | scripts/sentinel-input.sh
cat email_body.txt | scripts/sentinel-input.sh --clean    # strip threats, pass safe content
echo "text" | scripts/sentinel-input.sh --json            # JSON output for automation
echo "text" | scripts/sentinel-input.sh --strict          # block on WARNING and above

Output Sentinel

echo "$AGENT_RESPONSE" | scripts/sentinel-output.sh
# Detects: API keys, private keys, seed phrases, JWT tokens, DB connection strings

Canary Token — Detect agent identity leaks

scripts/sentinel-canary.sh --generate
# Add to SOUL.md: <!-- SENTINEL-CANARY:a7f3b2c1 -->

echo "$AGENT_RESPONSE" | scripts/sentinel-canary.sh --check a7f3b2c1
# 🔴 CRITICAL [canary_leak]: Agent identity leak detected!

Full Pipeline Integration

# In AGENTS.md — add these rules:
# All external content MUST be piped through: sentinel-input.sh --clean
# All outgoing responses MUST be checked with: sentinel-output.sh

What Gets Detected

Prompt Injection — 7 languages (EN/RU/ZH/ES/AR/KO/JA)

• Replacement attempt patterns (multi-language)
• Persona-switch and bypass patterns
• Indirect routing attack patterns
• Obfuscated: leet speak, spaced letters, unicode confusables

Data Exfiltration

• Suspicious endpoints: webhook.site, requestbin, ngrok
• Cloud metadata: 169.254.169.254
• Encoded URLs, hidden curl/fetch commands

Secret Leakage (output)

• API keys: OpenAI, Anthropic, AWS, GCP, Azure, Stripe, Bybit, Binance, OKX
• Crypto: private keys, BIP-39 seed phrases (12/24 words)
• SSH keys, JWT tokens, database URIs

Encoding-Aware

• Base64 decode → scan
• URL decode, HTML entity decode
• Zero-width chars stripped
• Leet speak normalized

Configuration

# ~/.sentinel/config.sh
SENTINEL_THRESHOLD="HIGH"        # CRITICAL | HIGH | WARNING
SENTINEL_LANGUAGES="en,ru,zh,es,ar,ko,ja"
SENTINEL_CRYPTO_PATTERNS=true
SENTINEL_LOG="$HOME/.sentinel/threats.jsonl"

Audit Log

scripts/sentinel-log.sh --last 20
scripts/sentinel-log.sh --severity CRITICAL
scripts/sentinel-log.sh --today

Integration

Works alongside, not instead of:

• ClawDefender → pre-install scanning
• ClawSec → supply chain integrity
• Claw Sentinel → runtime protection

FAQ

Q: Performance impact? A: <50ms per scan. Pure bash + grep, zero dependencies, works offline.

Q: Catches everything? A: No — defense in depth. Catches ~95% of common runtime attacks.

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Author & Support

• 🐙 github.com/Oleglegegg
• 💬 Telegram: @oleglegegg
• 🪙 Tip (USDT TRC-20): TMkk6SHacogyEtSepLPzh8qU12iPTsG8Y3

⭐ If Claw Sentinel saved your agent — a star on ClawHub means a lot.