Smuggling arbitrary data through an emoji

Re:Smuggling arbitrary data through an emoji by cscheid on Wednesday February 12, 2025 @09:28AM (#43025728)

My understanding is that "weird" unicode code points become https://en.wikipedia.org/wiki/Punycode. I used the 󠅘󠅕󠅜󠅜󠅟 (copy-pasted from the post, presumably with the payload in it) to type a fake domain into Chrome, and the Punycode I got appeared to not have any of the encoding bits.

However, I then pasted the emoji into the _query_ part of a URL. I pointed it to my own website, and sure enough, I can definitely see the payload in the nginx logs. Yikes.

Edit: I pasted the very same Emoji that 'paulgb used in their post before the parenthetical in the first paragraph, but it seems HN scrubs those from comments.

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Re:Smuggling arbitrary data through an emoji by bmicraft on Wednesday February 12, 2025 @11:05AM (#43026695)

domains get "punycode" encoded, urls get "url encoded"[1], which should make unicode characters stand out. That being said, browsers do accept some non-ascii characters in urls and convert them automatially, so theoretically you could put "invalid" characters into a link and have the browser convert it only after clicking. That might be a viable strategy.

[1] https://www.w3schools.com/tags//ref_urlencode.asp

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Re:Smuggling arbitrary data through an emoji by echeese on Wednesday February 12, 2025 @01:23PM (#43028156)

The emoji is gone but the content is still there.

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