HOMOGRAPH ATTACK AND CONFUSABILITY
Homograph is a
letter or string that has enough of a visual similarity to a different letter
or string that the two may be confused for one another.
Looks like amazon.com of course, but it’s not.
The first ‘a’ is the Cyrillic small letter a, not the English, or Latin rather,
small letter ‘a’, although they look identical they are from two different
languages. In your browser’s status bar you should see the Punycode encoded version
of the domain name:
http://www.xn--mazon-3ve.com/
Because DNS does not support Unicode (only a
subset of ASCII characters are allowed), we have IDN standards which define how
domain names with Unicode characters should be encoded. Punycode is the name of
the encoding mechanism. The above is often referred to as an IDN homograph
attack.
We have included another two examples below
which look identical to a human and they will still appear to be the same if
you copy them into your address bar:
and
The second URL has one character which has been
replaced. We have shown the URL below using the Unicode values of the second
’o’ is the Greek small letter.
These are very simple
examples but hopefully you can see the potential dangers of clicking on a link
just because it looks genuine. Aside from spoofing with lookalike
characters from completely different alphabets, we can do a bunch of spoofing just
within our own alphabets. For example, certain fonts make combinations of
characters hard to determine. Just like the letter’s ‘r’ and ‘n’ together can
look like the letter ‘m’: rn = m Zero’s can look like ‘O’ and the number 1 can
look like a lower case ‘l’.
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
- www.rnu11ets.com looks a lot like www.mullets.com
I have listed the same text here in several
different fonts, because in some fonts, you wouldn’t be able to tell the visual
difference between the two words. The visual appearance of characters has a lot
to do with the fonts used to display the glyph, not just the alphabet.
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