• dual_sport_dork 🐧🗡️@lemmy.world
      23·
      1 year ago

      Something somewhere is running an htmlspecialchars() or equivalent on whatever you input, probably as an attempt at “sanitizing” the text entered in titles/posts/comments. You know, to keep me from just inserting a javascript tag with src=‘http://pwned.ru/fu.js’ into a comment and have it to something naughty to anyone who loads the page.

      I’m certain these are being stored in the database as an & amp;, but they’re not being decoded back into an ampersand character upon display.

      • Agentseed@artemis.camp
        3·
        1 year ago

        would it not be possible for whatever’s decoding it to run arbitrary Javascript if done wrong? maybe that’s why it doesn’t exist yet?

        • dual_sport_dork 🐧🗡️@lemmy.world
          9·
          1 year ago

          The decode really, really, really should not be happening client side in Javascript. The backend should handle it before handing the text to the user’s browser. You are correct; If this is done client side it means a bad actor can mess with it and/or include an injection attack of some sort.

          Nothing client side should ever handle user input, except perhaps convenience features like flagging incomplete fields or kicking the cursor to the next input element when one is full (e.g. for phone numbers). Anything client side can be fucked with by the client. Validation needs to happen on the server side, before committing the input to the database (or doing whatever it’s going to do with it).

        • dual_sport_dork 🐧🗡️@lemmy.world
          6·
          1 year ago

          There are a lot of potential pitfalls any time you accept text input from a user, store it, and regurgitate it back to display on a user’s browser. The thing is, HTML (and all HTML-encapsulated scripting languages) are just text. So regular words and a block of Javascript that makes dancing polka-dotted hippos dance across your screen and incessantly play the Hamster Dance song at 200% volume are, without protections, input and stored exactly the same way. Preventing ne’er-do-wells from doing injection attacks with SQL calls, HTML, control and escape characters, Javascript, etc. is part of a whole industry.

          It appears lemmy does filter out raw HTML tags, at least. I tried to insert one in my last comment just for illustration and it was silently removed from the input.

            • 0xD@infosec.pub
              1·
              1 year ago

              That’s because the sanitization here is shit, but I bet you’d rather have that than be attacked by stored cross-site scripting attacks :)

  • ChaoticNeutralCzech@feddit.de
    11·
    1 year ago

    Yes, it’s annoying. However, there is a fullwidth ampersand available, as well as lots of other curly characters. I tried adding combining backslashes to those that miss that final stroke of ‘&’ but I gave up as they don’t align consistently across platforms.

    ＆﹠Ֆ𐒒౭𐓯꯴𖩒᱒𝛂̊ɑͦ𝛂ͦ

      • ChaoticNeutralCzech@feddit.de
        3·
        1 year ago

        Yes. The first one is a standard diacritical circle as seen in Swedish, the other two are a combining “o” above. The middle one is a standard alpha while the others are math script bold alphas. This is an attempt to create an ersatz “&” without the character 0x26 that appears as & in post titles and monospace text. The fullwidth ampersand is obviously the closest but it appears with space around it so “D＆D” looks more like “D & D” than “D&D”. Hence the attempts with weird characters (D𝛂ͦD, D꯴D, D𐓯D…). Unfortunately, some OSs (notably Windows 10) incorrectly draw most combining diacritics offset to the right of the base letter as a zero-width character.

        There is a pair of single (non-combining) characters I can demonstrate it with: a combination of K + combining comma below is supposed to look like Ķ but it looks kinda like Қ on Windows. However, Windows stacks combining diacritics so you can create impressively tall Z̷͍̝̿̈́͂̅͝͝͡͡a̷̢̡̢̙̬͕̯̹͍͖̰͕̦͉̘̪͗͂̑͂̑̾́̀̍͗̾́̄̕͝͝l̵̢̨̢̳̻̩̳̘͖͎͎̘̗̬̞͈͌g̸̨͈̠͔̖͎͇̟̍͗̈́̏̿̍̍͗̕o̷͓͎̙͉̯̱̊́͐͘ ̵̣͓̥͈̗̯̹̭̪͕͓̳̈́͌̐̈́̓̈́͑̌̚͡͝t̶̨̛̩̭̬̲͓̣͔̪̠̙̞͚̒͒̽͟͝ͅe̵̛̘͈̜͖̅͊́̅̌̇̒̐͑̚͠͝x̴͌͗͐͌̏͛̕͡͝ͅt̴̡̤̻̺̣̥̝̤̼̺̦̣͎̟́̊̂̈́̃͑̈́̈̈́ while some other platforms just print them over each other like a typewriter does.

    • ChaoticNeutralCzech@feddit.de
      3·
      1 year ago

      The problem exists in post titles and fullwidth text.

      Ampersand (＆): &
Less-than sign (ᐸ) : <
(The characters in parentheses are closest Unicode lookalikes)