bbaovanc.com/content/blog/discord-sex-hack/index.md

title	date	lastmod	toc	comments	authors	categories	tags	_build	resources
How the "Discord sex" (`s/e/x`) hack works	2022-05-11T21:11:17-05:00	2022-09-24T14:56:05-05:00	true	true	bbaovanc	tips-and-tricks	discord discord-tricks sed	list local	name src title feature example.webp Result after sending a GIF and then sending `s/e/x`. name src title default-sex default-sex.webp Fallback image on `txnor.com` name src title double-sex double-sex.webp Resulting image after typing `s/e/x` a second time. name src title chess chess.webp This happens once you type `s/w/ag` after having done `s/e/x`. name src title sword sword.webp This happens when you type `s/w/ord` after having done `s/e/x`. name src title sword-atk sword-atk.webp This happens when you type `s/d/dATK` name src title sword-def sword-def.webp This happens when you type `s/d/dDEF` name src title sword-hug sword-hug.webp This happens when you type `s/d/dHUG` name src title sword-win sword-win.webp Win screen on the `s/w/ord` game. name src title sword-lose sword-lose.webp Lose screen on the `s/w/ord` game. name src title 6969th 6969th.webp This happens on average (since it's randomized) every 6070th use. name src title math-challenge math-challenge.webp Math challenge example

There's this trick going around on Discord recently where if you send any GIF from Tenor, and then type s/e/x, then it turns it into a different meme GIF. Here's how it works.

{{< aside info >}} Credit goes to Rebane2001 (not me) for making this trick, and setting it up on txnor.com. {{< /aside >}}

The sed syntax

For operating systems based on Unix or Linux, there's usually a simple terminal command included called sed, which is most commonly used to run text replacement commands. Here's a very simple example of what a basic sed command looks like:

$ sed 's/hello/goodbye/'

Discord likely implemented this in order to appeal to IRC¹ users. Since IRC doesn't support editing messages, it's common for people to send messages in that format to tell people about changes to their previous message. Discord implemented this into both their web/desktop client and their iOS app, excluding the Android app.

Note that while real sed commands can get much more complicated, Discord's implementation doesn't support those advanced features².

{{< see-also "/blog/text-substitution-in-discord-using-sed" >}}

What does s/e/x do?

When you send a GIF using the GIF picker on Discord, it actually sends the link to the GIF, which is served by Tenor. For example, here's a GIF sent from Tenor:

https://tenor.com/view/cat-massage-gif-24282757

Running s/e/x will take the first occurrence of e and replace it with x. The link becomes the following (notice the bolded letter x):

https://txnor.com/view/cat-massage-gif-24282757

Then, all that's left to do is to buy the domain txnor.com, and write a simple program to run on it. In fact, it looks like that domain was purchased purely in order to make this trick possible³.

How does it display on Discord without redirecting?

When viewing any of the URLs on txnor.com in a normal web browser, you get redirected to a tweet. However, Discord is able to display the image without being redirected.

When Discord loads a website to generate an embed, it uses a user agent⁴ (which is a little piece of text which tells the server what your browser is) which looks something like this:

User-Agent: Mozilla/5.0 (compatible; Discordbot/2.0; +https://discordapp.com/)

The important part here is the word Discord. If you visit the website with your user agent set to anything containing Discord (case-insensitive)⁵, then it serves the image directly.

Default image

If you go to any URL on txnor.com that doesn't fit one of the existing patterns/games, then it returns this fallback image:

{{< figure src="default-sex" >}}

Extra features

Double sex

If you then run s/e/x a second time, then it changes to a different image:

{{< figure src="double-sex" >}}

This works in a simple way as well. The next e that appears in the URL is inside /view/. So, after typing s/e/x a second time, the URL becomes:

https://txnor.com/vixw/cat-massage-gif-24282757

Chess (s/w/ag)

Another cool feature is that you can play chess by typing s/w/ag after typing the initial message of s/e/x.

{{< figure src="chess" >}}

s/w/ord

If you do s/w/ord after s/e/x, then it starts a fighting game (titled "Wumpagotchi Adventures". You can use three commands: s/d/dATK, s/d/dDEF, and s/d/dHUG.

Here are a few example images:

Main s/w/ord screen

{{< figure src="sword" >}}

ATK command

{{< figure src="sword-atk" >}}

DEF command

{{< figure src="sword-def" >}}

HUG command

{{< figure src="sword-hug" >}}

Win screen

{{< figure src="sword-win" >}}

Lose screen

{{< figure src="sword-lose" >}}

6969th Discord Sexer

If you happen to get a one in 6970 chance, it will instead return a special image:

{{< figure src="6969th" >}}

Here's a snippet of the code that handles this chance:

# 6969th winner image (disable for chess)
if random.randint(0, 6969) == 6969 and "ag" not in name:
    web.header('Cache-Control', 'no-store')
    return six_nine

I believe it's supposed to be a 1/6969 chance, but random.randint in Python includes both numbers. That means that the possible numbers that it could pick would be 0, 1, ... 6968, 6969. If you were to count the numbers included in that sequence, it would total 6970.

Math challenge

Any URL that matches this regular expression will instead return a randomized math challenge:

{{< figure src="math-challenge" >}}

What's special is that the math challenge is set to not be cached.

How it works is that when each person's Discord client sends a request to the Discord CDN to get the image, the client caches that image. That means each client will see the same challenge problem, even if the user restarts the client. But separate clients will not have it cached, so they'll request it again themselves, and different numbers will be generated.

Discord sex is open source

Thanks to a comment from Rebane on this post, I now know that the server running on txnor.com is open source. See rebane2001/txnor-server.

YouTube video

Rebane also made a YouTube video about this trick. Make sure to check it out too!

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1. IRC (Internet Relay Chat) is a simple text-based chat system. It's a very old protocol, however its simplicity and minimalism is the main reason people choose it. It's not very popular anymore. ↩︎

2. Also note that in Discord's implementation, the trailing slash (after goodbye) can be ommitted (making it just s/hello/goodbye), but with the real sed command, it's required. ↩︎

3. According to a quick WHOIS lookup, the domain was registered on May 3, 2022. That's the same day that @Rebane tweeted about the new feature (going to https://txnor.com redirects to this tweet now the domain redirects to [Rebane's YouTube video about the hack]({{< ref "#youtube-video" >}})), so I assume that this is the only reason they bought the domain. ↩︎

4. If you actually care, there's a Wikipedia article, and a page on WhatIsMyIPAddress.com which also explain what a user agent is. ↩︎

5. According to the source code, it looks like Intel Mac OS X 11.6; rv:92.0 also triggers the same response. ↩︎