Dependency Vetting Skill

Purpose

Prevent supply chain attacks by vetting packages before installation:

• Detect typosquatting (e.g.,

  reqeusts

  instead of

  requests

  )
• Check for known vulnerabilities (CVEs)
• Verify package legitimacy (download counts, age, maintainer)
• Warn on low adoption or suspicious patterns

---

When to Trigger

Auto-trigger when detecting:

• pip install <package>

• pip3 install <package>

• npm install <package>

• yarn add <package>

• Modifications to

  requirements.txt

  ,

  package.json

  ,

  pyproject.toml

---

Vetting Protocol

Step 1: Parse Package Name

# Extract package name and version from command
# Examples:
#   pip install requests==2.28.0  → requests, 2.28.0
#   npm install lodash@4.17.21    → lodash, 4.17.21
#   pip install -r requirements.txt → parse file

Step 2: Typosquatting Check

Popular packages to check against:

Python:

requests, numpy, pandas, flask, django, fastapi, pydantic,
sqlalchemy, pytest, black, mypy, ruff, httpx, aiohttp,
beautifulsoup4, pillow, scipy, matplotlib, tensorflow, torch

JavaScript:

react, vue, angular, express, lodash, axios, moment,
webpack, babel, eslint, prettier, typescript, jest, mocha,
next, gatsby, tailwindcss, styled-components

Typosquatting detection:

def is_typosquat(package_name: str, known_packages: list[str]) -> tuple[bool, str]:
    """Check if package name is suspiciously similar to a known package."""
    import difflib

    for known in known_packages:
        # Exact match is fine
        if package_name == known:
            return False, ""

        # Check similarity ratio
        ratio = difflib.SequenceMatcher(None, package_name, known).ratio()
        if ratio > 0.85 and package_name != known:
            return True, f"Suspiciously similar to '{known}' (similarity: {ratio:.0%})"

        # Common typosquatting patterns
        patterns = [
            package_name.replace('-', ''),      # request vs requests
            package_name.replace('_', '-'),     # python_dateutil
            package_name + 's',                 # request → requests
            package_name[:-1] if len(package_name) > 3 else package_name,  # requests → request
        ]
        if known in patterns:
            return True, f"Possible typosquat of '{known}'"

    return False, ""

Step 3: Package Existence Verification

Python (PyPI):

# Check if package exists
pip index versions $PACKAGE_NAME 2>&1

# Or use API
curl -s "https://pypi.org/pypi/$PACKAGE_NAME/json" | jq '.info'

JavaScript (npm):

npm view $PACKAGE_NAME --json 2>&1

If package doesn't exist: BLOCK - likely typo or malicious attempt

Step 4: Metadata Analysis

Extract and analyze:

{
  "name": "package-name",
  "version": "1.2.3",
  "author": "author-name",
  "maintainers": ["maintainer1", "maintainer2"],
  "downloads_last_month": 1500000,
  "first_published": "2015-03-15",
  "last_updated": "2024-01-10",
  "repository_url": "https://github.com/org/repo",
  "license": "MIT"
}

Red flags:

• ⚠️ Package < 6 months old with low downloads
• ⚠️ No repository URL
• ⚠️ Author name similar to popular package author
• ⚠️ Recently changed maintainer
• ⚠️ No license specified
• ⚠️ Unusual install scripts

Step 5: Vulnerability Check

Python:

# Using pip-audit
pip-audit --requirement requirements.txt

# Or check specific package
pip-audit $PACKAGE_NAME

JavaScript:

# Using npm audit
npm audit --json

# Or check specific package
npm audit $PACKAGE_NAME

Severity levels:

• Critical: Known RCE, SQL injection, etc. → BLOCK
• High: Serious vulnerabilities → WARN (require acknowledgment)
• Medium/Low: → WARN (inform user)

---

Decision Matrix

Condition	Action	Message
Typosquat detected	BLOCK	"Package '$name' appears to be a typosquat of '$real'. Did you mean '$real'?"
Package doesn't exist	BLOCK	"Package '$name' not found. Check spelling."
Critical vulnerability	BLOCK	"Package has critical vulnerability CVE-XXXX. Use alternative or pin older version."
High vulnerability	WARN	"Package has high-severity vulnerability. Proceed with caution?"
Low downloads (<1000/month)	WARN	"Package has very low adoption. Verify it's legitimate."
New package (<3 months)	WARN	"Package is very new. Verify maintainer reputation."
No repository	WARN	"Package has no linked repository. Cannot verify source."
Clean	ALLOW	"Package vetted: [summary of checks passed]"

---

Output Format

{
  "package": "requests",
  "version": "2.28.0",
  "verdict": "ALLOW | WARN | BLOCK",
  "reason": "Brief explanation",

  "checks": {
    "typosquatting": {"passed": true, "details": null},
    "exists": {"passed": true, "details": "Found on PyPI"},
    "vulnerabilities": {"passed": true, "details": "No known CVEs"},
    "adoption": {"passed": true, "details": "51M downloads/month"},
    "age": {"passed": true, "details": "First published 2011-02-14"},
    "repository": {"passed": true, "details": "https://github.com/psf/requests"}
  },

  "recommendation": "Safe to install" | "Review warnings before proceeding" | "Do not install"
}

---

Example Interactions

Typosquat blocked:

User: pip install reqeusts

Skill output:
⛔ BLOCKED: Package 'reqeusts' appears to be a typosquat of 'requests'

Did you mean: pip install requests

This is a common supply chain attack vector. The legitimate package
is 'requests' (with correct spelling).

Low adoption warning:

User: pip install obscure-tool-xyz

Skill output:
⚠️ WARNING: Package 'obscure-tool-xyz' has low adoption

- Downloads last month: 47
- First published: 2024-11-01 (2 months ago)
- No linked repository

This package has very limited community validation.
Proceed with installation? [yes/no]

Critical vulnerability blocked:

User: pip install vulnerable-lib==1.0.0

Skill output:
⛔ BLOCKED: Package has critical vulnerability

CVE-2024-12345: Remote Code Execution
Affected versions: < 1.2.0
Fixed in: 1.2.0

Recommendation: pip install vulnerable-lib>=1.2.0

---

Remember

• Block typosquats aggressively - These are almost always malicious
• Warn on low adoption - But allow if user confirms
• Check vulnerabilities - Critical = block, High = warn
• Provide alternatives - When blocking, suggest the correct package
• Log all decisions - For audit trail