IDN Homograph Attack - Homographs in ASCII

Homographs in ASCII

ASCII has several characters or pairs of characters that look alike and are known as homographs (or homoglyphs). Spoofing attacks based on these similarities are known as homograph spoofing attacks. For example 0 (the number) and O (the letter), "l" lowercase L, and "I" uppercase "i".

In a typical example of a hypothetical attack, someone could register a domain name that appears almost identical to an existing domain but goes somewhere else. For example, the domain "rnicrosoft.com" contains "r" and "n", not "m". Other examples are G00GLE.COM which looks much like GOOGLE.COM in some fonts. Using a mix of uppercase and lowercase characters, googIe.com (capital i, not small L) looks much like google.com in some fonts. PayPal was a target of a phishing scam exploiting this, using the domain PayPaI.com. In certain narrow-spaced fonts such as Tahoma (the default address bar in Windows XP), placing a c in front of a j, l or i will produce homoglyphs such as cl cj ci (d g a).