Zerosuniverse
Cybersecurity

IDN Punycode (xn--) Homograph Attack & Spoofing Detector (2026)

Convert Internationalized Domain Names (IDN) between Unicode and ASCII Punycode (xn--), detect mixed-script Cyrillic/Greek/Latin confusable characters, and generate lookalike domain defensive watchlists.

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IDN Punycode (xn--) Homograph Attack & Spoofing Detector — Interactive Console
Runs locally in your browser • Instant output
Unicode Display Form
аpple.com
DNS Punycode (ACE Wire Form)
xn--pple-43d.com
Homograph Verdict
SPOOF ALERT: Impersonates apple.com
Character-by-Character Unicode Codepoint & Script Breakdown
а
U+0430
Cyrillic
Spoofs 'a'
p
U+0070
ASCII
p
U+0070
ASCII
l
U+006C
ASCII
e
U+0065
ASCII
.
U+002E
ASCII
c
U+0063
ASCII
o
U+006F
ASCII
m
U+006D
ASCII
Ready
Embed / Cite This Tool (Markdown & HTML)
GitHub / Reddit Markdown Badge[![IDN Punycode (xn--) Homograph Attack & Spoofing Detector](https://img.shields.io/badge/ZerosUniverse-Free_Tool-ff6a00)](https://www.zerosuniverse.com/tools/idn-homograph-punycode-phishing-detector/)
Blog / Documentation HTML Citation<a href="https://www.zerosuniverse.com/tools/idn-homograph-punycode-phishing-detector/">IDN Punycode (xn--) Homograph Attack & Spoofing Detector — ZerosUniverse</a>

2026 Quick-Reference Cheat Sheet & Benchmark Table: IDN Punycode (xn--) Homograph Attack & Spoofing Detector

Quick Answer & 2026 Technical Summary (idn homograph punycode detector)Updated 2026 Standard

An Internationalized Domain Name (IDN) homograph attack is a social engineering technique where an attacker registers a domain using non-Latin Unicode characters (such as Cyrillic 'а' U+0430, 'е' U+0435, 'о' U+043E, or Greek 'ο' U+03BF) that look pixel-identical to standard ASCII Latin letters. Use this interactive idn homograph punycode detector above to test punycode xn-- converter online, idn homograph attack scanner, and unicode confusable domain checker locally in your browser with zero server uploads.

Target Keyword Spec: idn homograph punycode detector | Modules: Real-Time RFC 3492 Punycode (xn--) Encoder & Decoder • Unicode UTS #39 Mixed-Script & Skeleton Inspector • Character-by-Character Visual X-Ray Diff Grid
Primary Focus: idn homograph punycode detector
Core Capability: punycode xn-- converter online
Privacy Mode: 100% Client-Side (Zero Upload)
Technical Parameter / ModuleStandard / Keyword SpecArchitecture & Validation RuleOperational Use Case (2026)
Real-Time RFC 3492 Punycode (xn--) Encoder & Decoderpunycode xn-- converter onlineTranslate deceptive Unicode domains (like аррӏе.com) into their canonical D...SOC Phishing Link & Email Header Triage
Unicode UTS #39 Mixed-Script & Skeleton Inspectoridn homograph attack scannerAnalyze every codepoint's hex value (U+XXXX), Unicode script block (Latin, ...Brand Protection & Defensive Domain Registration
Character-by-Character Visual X-Ray Diff Gridunicode confusable domain checkerHighlight deceptive non-ASCII homoglyphs (such as Cyrillic Small Letter A U...CEH & Red Team Social Engineering Simulations
Execution & Privacy Architecture100% Client-Side WebCrypto / JS Sandbox0 Bytes Sent to External ServersSafe for internal SOC & authorized lab artifacts
NIST SP 800-53 / OWASP AlignmentOWASP ASVS v4.0.3 / NIST CSF 2.0Deterministic Rule & Header VerificationMaps findings to actionable hardening controls
Cryptographic & Entropy StandardSHA-256 / AES-256-GCM / Argon2id≥ 128-bit Effective Security MarginMeets 2026 post-quantum & zero-trust baselines
In-Depth ZerosUniverse Tutorial

CEH Module 09: Social Engineering & Phishing Techniques

Read our complete step-by-step editorial guide, architecture breakdown, and defensive best practices on ZerosUniverse.

Read Full Guide

How to Use IDN Punycode (xn--) Homograph Attack & Spoofing Detector

01

Paste a Suspicious Domain, URL, or Punycode String

Enter any Unicode domain, full URL, or xn-- Punycode string—or load famous real-world homograph examples like Cyrillic 'аррӏе.com' or 'mіcrosoft.com'.

02

Inspect the Character Codepoint & Script X-Ray

Examine the character breakdown table showing each glyph's Unicode point (e.g., U+0430 CYRILLIC SMALL LETTER A), script family, and ASCII lookalike target.

03

Verify UTS #39 Mixed-Script & Whole-Script Spoof Risk

Check the calculated risk verdict (Safe ASCII, Legitimate IDN, Mixed-Script Confusable, or Whole-Script Homograph Attack) and browser address bar behavior.

04

Generate Defensive Homograph Permutations

Switch to the Brand Permutator tab to generate confusable Punycode variants of your domain for DNS blocklists and SIEM threat hunting.

Key Capabilities & Technical Architecture

Real-Time RFC 3492 Punycode (xn--) Encoder & Decoder

Translate deceptive Unicode domains (like аррӏе.com) into their canonical DNS ASCII Compatible Encoding (xn--80ak6aa92e.com) and back in real time.

Unicode UTS #39 Mixed-Script & Skeleton Inspector

Analyze every codepoint's hex value (U+XXXX), Unicode script block (Latin, Cyrillic, Greek, Hebrew, Cherokee), and visual confusable skeleton mapping.

Character-by-Character Visual X-Ray Diff Grid

Highlight deceptive non-ASCII homoglyphs (such as Cyrillic Small Letter A U+0430 vs. Latin U+0061) in high-contrast red cards with side-by-side glyph comparison.

Defensive Brand Permutator & Phishing Watchlist Generator

Input your brand domain to enumerate possible single-character and whole-script homograph permutations with ready-to-copy Punycode strings for SIEM/DNS sinkhole rules.

Practical Use Cases

SOC Phishing Link & Email Header Triage

Paste suspicious URLs from spear-phishing emails or SMS smishing lures to immediately expose hidden Cyrillic or Greek substitutions masquerading as trusted brands.

Brand Protection & Defensive Domain Registration

Generate high-risk Punycode (xn--) lookalike permutations of your corporate domain to monitor Certificate Transparency (CT) logs or block at enterprise DNS resolvers.

CEH & Red Team Social Engineering Simulations

Demonstrate how whole-script Cyrillic homographs bypass naive visual inspection and test whether modern browsers (Chrome, Firefox, Safari) trigger Punycode fallback warnings.

Frequently Asked Questions (FAQs)

What is an IDN homograph attack?+

An Internationalized Domain Name (IDN) homograph attack is a social engineering technique where an attacker registers a domain using non-Latin Unicode characters (such as Cyrillic 'а' U+0430, 'е' U+0435, 'о' U+043E, or Greek 'ο' U+03BF) that look pixel-identical to standard ASCII Latin letters.

How does Punycode (xn--) encoding work in DNS?+

Because the core Domain Name System (DNS) historically only supports ASCII characters (A-Z, 0-9, and hyphens), RFC 3492 defines Punycode (Bootstring encoding). Any domain label containing non-ASCII characters is prefixed with 'xn--' followed by the ASCII characters and encoded delta offsets of the Unicode codepoints.

Why did the famous 'аррӏе.com' (xn--80ak6aa92e.com) attack fool web browsers?+

Early browser defenses only blocked 'mixed-script' labels (combining Latin and Cyrillic inside the same word). Security researcher Xudong Zheng demonstrated that by writing 'apple' using 100% Cyrillic characters (а-р-р-ӏ-е), browsers treated it as a legitimate single-script Cyrillic word and rendered 'apple.com' in the URL bar.

How does Unicode Technical Standard #39 (UTS #39) detect confusables?+

UTS #39 defines a 'skeleton' algorithm: it normalizes strings via NFD decomposition, maps every character through the Unicode confusables table to a canonical prototype glyph, and re-applies NFD. If two distinct strings produce the exact same skeleton, they are visually confusable.

How can organizations defend against Punycode phishing?+

Organizations should monitor Certificate Transparency (CT) logs for 'xn--' certificates matching their brand skeleton, block newly registered IDN lookalikes at the Secure Email Gateway (SEG) and DNS resolver level, and adopt FIDO2/WebAuthn passkeys which bind cryptographically to the exact ASCII RP ID (never falling for visual spoofing).