Oops, wrong person.

Remember, always validate your inputs.

This is awesome. We need more of this to help us fight the coming war

Whoops, the mask slipped and we all saw the bot behind it.

Mask slipped? The bot saw a person speak code and was like l, rips off mask Comrade!
- Lol good point.
I think there's a second mask. Who sends oops wrong person in the same text message?

Thought that seemed really cute. Nice way to try to break through social anxiety.

Then I saw that it started as a wrong number message. Then I realised…

Damn scam bots!

Modern version of this will be ChatGPT jailbreak messages

In the future, bots are going to get so annoyed with people pretending to be bots when they just want to talk to other bots!

why bother with the variations?

think they're hoping to knock the same victim more than once?

messed up

Maybe it's an attempt to evade automated systems that check for spam.
Probably a basic way to evade spam detection. If you start sending the exact same message to 500 people, most chat services will shut that shit down in an instant. But if you send unique messages, it makes you look more like a real person, and the chat system may let it slide.
- What's bad is that modern spam detection can employ semantic algorithms so it would still catch all of them as the I'm as message. The use of synonyms in the optionals is a huge vulnerability in the scam.
So that their fixed script isn't so predictable that we can just nuke them by looking for identical conversations.
Could be to match the style of the target, to try and make the conversation feel more natural for them.
I would say more likely to get around bot protection.

How does this exploit work? I understand that inputs were not sanitized, but what did the injected code do?

My guess would be the response text is passed through a rudimentary templating engine that looks for { and }. Somehow it must be processing the whole chat history. The templater fails at the unexpected braces in the code block and then just gives up (probably a try-catch ignores the error and sends the message anyway).
- So the attack would just be a } then?
I don't think the code is doing anything, it looks like it might be the brackets.
That effectively the spam script has like a greedy template matcher that is trying to template the user message with the brackets and either (a) chokes on an exception so that the rest is spit out with no templating processor, or (b) completes so that it doesn't apply templating to the other side of the conversation.
So { a :'b'} might work instead.

This is the best thing ive seen this week!