What it does. Generate domain permutations with dnstwist and check DNS resolution Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-typosquatting-domains-with-dnstwist, or copy the skill folder into ~/.claude/skills/analyzing-typosquatting-domains-with-dnstwist/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/analyzing-typosquatting-domains-with-dnstwist/SKILL.md

SKILL.md (verbatim)

name: analyzing-typosquatting-domains-with-dnstwist
description: Generate domain permutations with dnstwist and check DNS resolution
  to detect typosquatting, homograph phishing, and brand impersonation domains registered
  against your organization. Use when asked to monitor for lookalike domains, investigate
  a phishing domain, or assess brand-impersonation risk.
domain: cybersecurity
subdomain: threat-intelligence
tags:
- dnstwist
- typosquatting
- phishing
- domain-monitoring
- brand-protection
- homograph
- dns
- threat-intelligence
version: '1.0'
author: mahipal
license: Apache-2.0
atlas_techniques:
- AML.T0073
- AML.T0052
nist_csf:
- ID.RA-01
- ID.RA-05
- DE.CM-01
- DE.AE-02
mitre_attack:
- T1583.001
- T1566.002
- T1598.003
- T1583.006
mitre_f3:
  version: '1.1'
  tactics:
  - resource-development
  - reconnaissance
  - initial-access
  techniques:
  - id: T1583.001
    name: 'Acquire Infrastructure: Domains'
    tactic: resource-development
    source: attack
  - id: F1020.002
    name: 'Create Fake Materials: Fake Website'
    tactic: resource-development
    source: f3
  - id: T1598
    name: Phishing for Information
    tactic: reconnaissance
    source: attack
  - id: T1593
    name: Search Open Websites/Domains
    tactic: reconnaissance
    source: attack
  - id: T1660
    name: Phishing
    tactic: initial-access
    source: attack

Analyzing Typosquatting Domains with DNSTwist

Overview

DNSTwist is a domain name permutation engine that generates similar-looking domain names to detect typosquatting, homograph phishing attacks, and brand impersonation. It creates thousands of domain permutations using techniques like character substitution, transposition, insertion, omission, and homoglyph replacement, then checks DNS records (A, AAAA, NS, MX), calculates web page similarity using fuzzy hashing (ssdeep) and perceptual hashing (pHash), and identifies potentially malicious registered domains.

When to Use

• When investigating security incidents that require analyzing typosquatting domains with dnstwist
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Python 3.9+ with dnstwist installed (pip install dnstwist[full])
• Optional: GeoIP database for IP geolocation
• Optional: Shodan API key for enrichment
• Network access to perform DNS queries
• Understanding of DNS record types and domain registration

Key Concepts

Domain Permutation Techniques

DNSTwist generates permutations using: addition (appending characters), bitsquatting (bit-flip errors), homoglyph (visually similar Unicode characters like rn vs m), hyphenation (adding hyphens), insertion (inserting characters), omission (removing characters), repetition (repeating characters), replacement (replacing with adjacent keyboard keys), subdomain (inserting dots), transposition (swapping adjacent characters), vowel-swap (swapping vowels), and dictionary-based (appending common words).

Fuzzy Hashing and Visual Similarity

DNSTwist uses ssdeep (locality-sensitive hash) to compare HTML content and pHash (perceptual hash) to compare screenshots of web pages. This helps identify cloned phishing sites that visually mimic the legitimate site. A high similarity score indicates a likely phishing page.

Detection Workflow

The typical workflow is: generate domain permutations -> resolve DNS records -> check for registered domains -> compare web page similarity -> flag suspicious domains -> alert security team -> request takedown. For a typical corporate domain, dnstwist generates 5,000-10,000 permutations.

Workflow

Step 1: Basic Domain Permutation Scan

import subprocess
import json
import csv
from datetime import datetime

def run_dnstwist_scan(domain, output_file=None):
    """Run dnstwist scan against a target domain."""
    cmd = [
        "dnstwist",
        "--registered",     # Only show registered domains
        "--format", "json", # Output in JSON
        "--nameservers", "8.8.8.8,1.1.1.1",
        "--threads", "50",
        "--mxcheck",        # Check MX records
        "--ssdeep",         # Fuzzy hash comparison
        "--geoip",          # GeoIP lookup
        domain,
    ]

    print(f"[*] Scanning permutations for: {domain}")
    result = subprocess.run(cmd, capture_output=True, text=True, timeout=600)

    if result.returncode == 0:
        results = json.loads(result.stdout)
        registered = [r for r in results if r.get("dns_a") or r.get("dns_aaaa")]
        print(f"[+] Found {len(registered)} registered lookalike domains")

        if output_file:
            with open(output_file, "w") as f:
                json.dump(registered, f, indent=2)
            print(f"[+] Results saved to {output_file}")

        return registered
    else:
        print(f"[-] dnstwist error: {result.stderr}")
        return []

results = run_dnstwist_scan("example.com", "typosquat_results.json")

Step 2: Analyze and Prioritize Results

def analyze_results(results, legitimate_ips=None):
    """Analyze dnstwist results and prioritize threats."""
    legitimate_ips = legitimate_ips or set()
    high_risk = []
    medium_risk = []
    low_risk = []

    for entry in results:
        domain = entry.get("domain", "")
        fuzzer = entry.get("fuzzer", "")
        dns_a = entry.get("dns_a", [])
        dns_mx = entry.get("dns_mx", [])
        ssdeep_score = entry.get("ssdeep_score", 0)

        risk_score = 0
        risk_factors = []

        # High similarity to legitimate site
        if ssdeep_score and ssdeep_score > 50:
            risk_score += 40
            risk_factors.append(f"high web similarity ({ssdeep_score}%)")

        # Has MX records (can receive email / phishing)
        if dns_mx:
            risk_score += 20
            risk_factors.append("has MX records (email capable)")

        # Recently registered (if whois data available)
        whois_created = entry.get("whois_created", "")
        if whois_created:
            try:
                created = datetime.fromisoformat(whois_created.replace("Z", "+00:00"))
                age_days = (datetime.now(created.tzinfo) - created).days
                if age_days < 30:
                    risk_score += 30
                    risk_factors.append(f"recently registered ({age_days} days)")
                elif age_days < 90:
                    risk_score += 15
                    risk_factors.append(f"registered {age_days} days ago")
            except (ValueError, TypeError):
                pass

        # Homoglyph attacks are highest risk
        if fuzzer == "homoglyph":
            risk_score += 25
            risk_factors.append("homoglyph (visually identical)")
        elif fuzzer in ("addition", "replacement", "transposition"):
            risk_score += 10
            risk_factors.append(f"permutation type: {fuzzer}")

        # Not pointing to legitimate infrastructure
        if dns_a and not set(dns_a).intersection(legitimate_ips):
            risk_score += 10
            risk_factors.append("different IP from legitimate")

        entry["risk_score"] = risk_score
        entry["risk_factors"] = risk_factors

        if risk_score >= 50:
            high_risk.append(entry)
        elif risk_score >= 25:
            medium_risk.append(entry)
        else:
            low_risk.append(entry)

    high_risk.sort(key=lambda x: x["risk_score"], reverse=True)
    medium_risk.sort(key=lambda x: x["risk_score"], reverse=True)

    print(f"\n=== Typosquatting Analysis ===")
    print(f"High Risk: {len(high_risk)}")
    print(f"Medium Risk: {len(medium_risk)}")
    print(f"Low Risk: {len(low_risk)}")

    if high_risk:
        print(f"\n--- High Risk Domains ---")
        for entry in high_risk[:10]:
            print(f"  {entry['domain']} (score: {entry['risk_score']})")
            for factor in entry['risk_factors']:
                print(f"    - {factor}")

    return {"high": high_risk, "medium": medium_risk, "low": low_risk}

analysis = analyze_results(results, legitimate_ips={"93.184.216.34"})

Step 3: Continuous Monitoring Pipeline

import time
import hashlib

class TyposquatMonitor:
    def __init__(self, domains, known_domains_file="known_typosquats.json"):
        self.domains = domains
        self.known_file = known_domains_file
        self.known_domains = self._load_known()

    def _load_known(self):
        try:
            with open(self.known_file, "r") as f:
                return json.load(f)
        except FileNotFoundError:
            return {}

    def _save_known(self):
        with open(self.known_file, "w") as f:
            json.dump(self.known_domains, f, indent=2)

    def scan_all_domains(self):
        """Scan all monitored domains for new typosquats."""
        new_findings = []
        for domain in self.domains:
            results = run_dnstwist_scan(domain)
            for entry in results:
                domain_key = entry.get("domain", "")
                if domain_key not in self.known_domains:
                    entry["first_seen"] = datetime.now().isoformat()
                    entry["monitored_domain"] = domain
                    self.known_domains[domain_key] = entry
                    new_findings.append(entry)
                    print(f"  [NEW] {domain_key} ({entry.get('fuzzer', '')})")

        self._save_known()
        print(f"\n[+] New typosquatting domains found: {len(new_findings)}")
        return new_findings

    def generate_alert(self, findings):
        """Generate alert for new high-risk typosquatting domains."""
        analysis = analyze_results(findings)
        alerts = []
        for entry in analysis["high"]:
            alerts.append({
                "severity": "HIGH",
                "domain": entry["domain"],
                "target": entry.get("monitored_domain", ""),
                "risk_score": entry["risk_score"],
                "risk_factors": entry["risk_factors"],
                "dns_a": entry.get("dns_a", []),
                "dns_mx": entry.get("dns_mx", []),
                "timestamp": datetime.now().isoformat(),
            })
        return alerts

monitor = TyposquatMonitor(["mycompany.com", "mycompany.org"])
new_findings = monitor.scan_all_domains()
alerts = monitor.generate_alert(new_findings)

Step 4: Export for Blocklist and Takedown

def export_blocklist(analysis, output_file="blocklist.txt"):
    """Export high-risk domains as blocklist for firewall/proxy."""
    domains = []
    for entry in analysis["high"] + analysis["medium"]:
        domain = entry.get("domain", "")
        if domain:
            domains.append(domain)

    with open(output_file, "w") as f:
        f.write(f"# Typosquatting blocklist generated {datetime.now().isoformat()}\n")
        for d in sorted(set(domains)):
            f.write(f"{d}\n")

    print(f"[+] Blocklist saved: {len(domains)} domains -> {output_file}")
    return domains

def generate_takedown_report(high_risk_domains):
    """Generate takedown request report."""
    report = f"""# Domain Takedown Request
Generated: {datetime.now().isoformat()}

## Summary
{len(high_risk_domains)} domains identified as potential typosquatting/phishing.

## Domains Requiring Takedown
"""
    for entry in high_risk_domains:
        report += f"""
### {entry['domain']}
- **Permutation Type**: {entry.get('fuzzer', 'unknown')}
- **IP Address**: {', '.join(entry.get('dns_a', ['N/A']))}
- **MX Records**: {', '.join(entry.get('dns_mx', ['N/A']))}
- **Risk Score**: {entry.get('risk_score', 0)}
- **Risk Factors**: {'; '.join(entry.get('risk_factors', []))}
- **Web Similarity**: {entry.get('ssdeep_score', 'N/A')}%
"""
    with open("takedown_report.md", "w") as f:
        f.write(report)
    print("[+] Takedown report generated: takedown_report.md")

export_blocklist(analysis)
generate_takedown_report(analysis["high"])

Validation Criteria

• DNSTwist generates domain permutations for target domain
• DNS resolution identifies registered lookalike domains
• Web similarity scoring detects cloned phishing pages
• Risk scoring prioritizes domains by threat level
• Continuous monitoring detects newly registered typosquats
• Blocklist and takedown reports generated correctly

References

• dnstwist GitHub Repository
• dnstwister Online Service
• HawkEye: Detect Typosquatting with DNSTwist
• Darktrace: Monitoring Typosquatting Domains
• Security Risk Advisors: Domain Monitoring
• Conscia: How to Detect Typosquatting

Other files in this skill

• LICENSE
• references/api-reference.md
• scripts/agent.py

references/api-reference.md (verbatim)

API Reference: Typosquatting Detection with dnstwist

dnstwist CLI

Syntax

dnstwist example.com                    # Basic scan
dnstwist -r example.com                 # Resolve DNS
dnstwist -r -f json example.com         # JSON output
dnstwist -r -f csv example.com          # CSV output
dnstwist -r --ssdeep example.com        # Fuzzy hashing comparison
dnstwist -r --phash example.com         # Perceptual hash (screenshot)
dnstwist -r -w wordlist.txt example.com # Dictionary-based
dnstwist --nameservers 8.8.8.8 example.com  # Custom DNS

Fuzzing Techniques

Output Fields

Python Integration

Installation

pip install dnstwist

CLI via subprocess

import subprocess, json
result = subprocess.run(
    ["dnstwist", "-r", "-f", "json", "example.com"],
    capture_output=True, text=True)
domains = json.loads(result.stdout)
for d in domains:
    if d.get("dns_a"):
        print(f"{d['domain']} -> {d['dns_a']}")

WHOIS Lookup

import whois
w = whois.whois("suspicious-domain.com")
print(w.creation_date, w.registrar)

VirusTotal Domain Check

curl -H "x-apikey: KEY" \
  "https://www.virustotal.com/api/v3/domains/<domain>"

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