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Strange (unicode?) Characters

A user places some strange characters on my site, and I would like to block them from doing this, but without blocking the characters used in foreign languages ​​... Therefore, using a regular expression such as [a-z0-9!@#$%^&*()...]is not an option.

Can someone explain to me what is happening here, break down why it shows how this happens. How are characters created and how can I prevent them from doing this?
:

♥̧̧̧̛̣̘̟̘̥͓̫̪̹̪̪̮̯̞̘̙̦̝̭̭͕̜̰̩̗̟̹͔̜̥̟̗̗̥̦̠̖̫͕̺̻̞̥̹͇̱̥̥̻͇̦̙̣͊͗̉̽̈́̉͑̀́̃͒̏͋̃̅̇̊̏̎̈́͊͐̉͑̄̌̉́̈́́́̅̇͌̽̽͗́̄̾̓̈́̇̅͛́̈́͐̽̔̌̋̌̾́̿͌̔͊͆̈́̉́̎̔̊͗̊̂̎̍̏̈̀̏͋͌̋̽̄̐̽͐̀͘̕̕͘̕̚̚̚͘͜͜͜͠͝͠͝͠͝




Thanks

EDIT: So they are used for accents? Is there a common practice or way to prevent users from using users without completely blocking them? I don’t know enough about foreign languages ​​or their actual use / purpose, so creating something that restricts the use of matching characters is beyond my capabilities .: - /

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3 answers

. é e-sharp , U + 00E9 (LATIN_SMALL_LETTER_E_WITH_ACUTE), U + 0065 U + 0301 (LATIN_SMALL_LETTER_E COMBINING_ACUTE_ACENT), .

:

codepoint   glyph   escaped    UTF-8           info
=======================================================================
U+2665      ♥       \u2665     e2,99,a5,       MISCELLANEOUS_SYMBOLS, OTHER_SYMBOL
U+034a      ͊       \u034a     cd,8a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0360      ͠       \u0360     cd,a0,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0357      ͗       \u0357     cd,97,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0309      ̉       \u0309     cc,89,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033d      ̽       \u033d     cc,bd,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0344      ̈́       \u0344     cd,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0309      ̉       \u0309     cc,89,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0351      ͑       \u0351     cd,91,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0340      ̀       \u0340     cd,80,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035d      ͝       \u035d     cd,9d,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0301      ́       \u0301     cc,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0303      ̃       \u0303     cc,83,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0352      ͒       \u0352     cd,92,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030f      ̏       \u030f     cc,8f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034b      ͋       \u034b     cd,8b,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0303      ̃       \u0303     cc,83,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0305      ̅       \u0305     cc,85,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0307      ̇       \u0307     cc,87,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030a      ̊       \u030a     cc,8a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030f      ̏       \u030f     cc,8f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030e      ̎       \u030e     cc,8e,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0344      ̈́       \u0344     cd,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034a      ͊       \u034a     cd,8a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0350      ͐       \u0350     cd,90,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0309      ̉       \u0309     cc,89,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0351      ͑       \u0351     cd,91,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0304      ̄       \u0304     cc,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030c      ̌       \u030c     cc,8c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0309      ̉       \u0309     cc,89,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0301      ́       \u0301     cc,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0344      ̈́       \u0344     cd,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0341      ́       \u0341     cd,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0301      ́       \u0301     cc,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0305      ̅       \u0305     cc,85,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0307      ̇       \u0307     cc,87,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034c      ͌       \u034c     cd,8c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033d      ̽       \u033d     cc,bd,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033d      ̽       \u033d     cc,bd,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0357      ͗       \u0357     cd,97,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0301      ́       \u0301     cc,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0360      ͠       \u0360     cd,a0,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0304      ̄       \u0304     cc,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033e      ̾       \u033e     cc,be,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0343      ̓       \u0343     cd,83,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0344      ̈́       \u0344     cd,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0307      ̇       \u0307     cc,87,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0358      ͘       \u0358     cd,98,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0305      ̅       \u0305     cc,85,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035d      ͝       \u035d     cd,9d,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035b      ͛       \u035b     cd,9b,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0301      ́       \u0301     cc,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0344      ̈́       \u0344     cd,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0350      ͐       \u0350     cd,90,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033d      ̽       \u033d     cc,bd,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0314      ̔       \u0314     cc,94,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030c      ̌       \u030c     cc,8c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030b      ̋       \u030b     cc,8b,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030c      ̌       \u030c     cc,8c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033e      ̾       \u033e     cc,be,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0360      ͠       \u0360     cd,a0,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0301      ́       \u0301     cc,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033f      ̿       \u033f     cc,bf,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034c      ͌       \u034c     cd,8c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0314      ̔       \u0314     cc,94,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0315      ̕       \u0315     cc,95,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034a      ͊       \u034a     cd,8a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0346      ͆       \u0346     cd,86,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0344      ̈́       \u0344     cd,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0309      ̉       \u0309     cc,89,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035d      ͝       \u035d     cd,9d,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0341      ́       \u0341     cd,81,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0315      ̕       \u0315     cc,95,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030e      ̎       \u030e     cc,8e,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0314      ̔       \u0314     cc,94,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030a      ̊       \u030a     cc,8a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0357      ͗       \u0357     cd,97,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0358      ͘       \u0358     cd,98,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030a      ̊       \u030a     cc,8a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0315      ̕       \u0315     cc,95,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0302      ̂       \u0302     cc,82,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030e      ̎       \u030e     cc,8e,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030d      ̍       \u030d     cc,8d,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030f      ̏       \u030f     cc,8f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0308      ̈       \u0308     cc,88,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0340      ̀       \u0340     cd,80,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030f      ̏       \u030f     cc,8f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031a      ̚       \u031a     cc,9a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034b      ͋       \u034b     cd,8b,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031a      ̚       \u031a     cc,9a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031a      ̚       \u031a     cc,9a,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+034c      ͌       \u034c     cd,8c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+030b      ̋       \u030b     cc,8b,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033d      ̽       \u033d     cc,bd,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0304      ̄       \u0304     cc,84,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0310      ̐       \u0310     cc,90,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033d      ̽       \u033d     cc,bd,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0350      ͐       \u0350     cd,90,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031b      ̛       \u031b     cc,9b,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0358      ͘       \u0358     cd,98,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0300      ̀       \u0300     cc,80,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0323      ̣       \u0323     cc,a3,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0318      ̘       \u0318     cc,98,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031f      ̟       \u031f     cc,9f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035c      ͜       \u035c     cd,9c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0318      ̘       \u0318     cc,98,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035c      ͜       \u035c     cd,9c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0325      ̥       \u0325     cc,a5,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0353      ͓       \u0353     cd,93,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032b      ̫       \u032b     cc,ab,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032a      ̪       \u032a     cc,aa,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0339      ̹       \u0339     cc,b9,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032a      ̪       \u032a     cc,aa,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032a      ̪       \u032a     cc,aa,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+035c      ͜       \u035c     cd,9c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032e      ̮       \u032e     cc,ae,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032f      ̯       \u032f     cc,af,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0327      ̧       \u0327     cc,a7,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031e      ̞       \u031e     cc,9e,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0318      ̘       \u0318     cc,98,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0319      ̙       \u0319     cc,99,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0326      ̦       \u0326     cc,a6,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031d      ̝       \u031d     cc,9d,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032d      ̭       \u032d     cc,ad,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032d      ̭       \u032d     cc,ad,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0355      ͕       \u0355     cd,95,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031c      ̜       \u031c     cc,9c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0330      ̰       \u0330     cc,b0,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0329      ̩       \u0329     cc,a9,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0317      ̗       \u0317     cc,97,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031f      ̟       \u031f     cc,9f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0339      ̹       \u0339     cc,b9,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0354      ͔       \u0354     cd,94,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031c      ̜       \u031c     cc,9c,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0325      ̥       \u0325     cc,a5,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031f      ̟       \u031f     cc,9f,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0317      ̗       \u0317     cc,97,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0317      ̗       \u0317     cc,97,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0325      ̥       \u0325     cc,a5,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0326      ̦       \u0326     cc,a6,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0320      ̠       \u0320     cc,a0,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0316      ̖       \u0316     cc,96,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+032b      ̫       \u032b     cc,ab,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0355      ͕       \u0355     cd,95,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033a      ̺       \u033a     cc,ba,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0327      ̧       \u0327     cc,a7,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033b      ̻       \u033b     cc,bb,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+031e      ̞       \u031e     cc,9e,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0325      ̥       \u0325     cc,a5,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0327      ̧       \u0327     cc,a7,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0339      ̹       \u0339     cc,b9,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0347      ͇       \u0347     cd,87,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0331      ̱       \u0331     cc,b1,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0325      ̥       \u0325     cc,a5,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0325      ̥       \u0325     cc,a5,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+033b      ̻       \u033b     cc,bb,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0347      ͇       \u0347     cd,87,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0326      ̦       \u0326     cc,a6,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0319      ̙       \u0319     cc,99,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK
U+0323      ̣       \u0323     cc,a3,          COMBINING_DIACRITICAL_MARKS, NON_SPACING_MARK

, :

+4

Allowing users to "send weird characters" probably allows them to do far more damage than just weird text. Check for example. for cross-site scripting and similar attacks. Make sure that everything you use to work with this functionality is related to sniffing (safe) and well configured. This should get rid of the problem that bothers you as a side effect.

-5
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Source: https://habr.com/ru/post/1530484/

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