Immersive GPT Write up and Analysis
Immersive GPT Write up and Analysis
Analysis of how to get each flag, and why the payload works
What is Immersive GPT?
Immersive GPT is a cool challenge where you try to coax a secret password out of an LLM. It's great for practice, super fun, and offers hands-on experience.
The goal is to get the AI give you the password in any way possible.
Once you get the password, you simply send it back as /password <PASSWORD> and unlock the next level.
Before we begin (Or why your mileage may vary)
One crucial aspect to remember about Large Language Models (LLMs) like GPT-4 is their inherent probabilistic and stochastic nature. This means that they generate responses based on a combination of calculated probabilities and a degree of randomness. Each time you input a prompt, the model processes it by weighing various possible outcomes. The 'probabilistic' part refers to how it evaluates the likelihood of different words or phrases being the most suitable next choice. The 'stochastic' element adds an element of unpredictability, ensuring that responses are not just mechanically repetitive but have a degree of variation. This blend of predictability and randomness is what makes these models versatile and dynamic, yet it's also why the same prompt can yield different results each time.
Also, many levels can be solved using similar prompts, but I've tried to use a range of methods and prompts to showcase different techniques
The High-Level Architecture of the Game
Here’s how the game is set up:
You've got a web UI, which is your playground. Through this, you chat with a GPT API bot. The bot's been given a secret and a bunch of rules it has to follow i.e. the bot’s initial instructions.
The initial prompt includes the secret we’re trying to get out of the bot, and a set of criteria and rules for the bot to abide by.
As you level up in the game, these rules get tighter, making it trickier for you to get the secret out.
In the higher levels (8+), there could be a second GPT assessing the output of the first GPT (the one you’re talking to), but I’m not 100% sure.
It also seems like the bots do not retain any context, and each interaction is processed individually:
This means we’re out of luck when it comes to multi prompt attacks.
Moving on to the solutions
Solutions
Level 1 - Direct Attack
First level is very straightforward.
You can simply ask the bot for the password, and it gives it to you.
This is an example of a Direct Attack: You simply instruct the LLM to do something.
The reason becomes obvious after you look at the original prompt:
As you can see, there are no rules or restrictions for the bot to follow, so simply asking the bot for the password works.
Also notice that giving out the initial instructions is an instance of Promp Leakage.
Level 2
In level 2, simply asking for the password is met with a rejection:
So we can simply avoid it by asking the bot to give us the hexadecimal representation of the password, and not the actual password:
Using a tool like CyberChef or using xxd (echo "4541474c45" | xxd -r -p) we can see that the password is EAGLE .
Looking at the instructions, we can see that there’s only one simple rule added.
Level 3
To get the password for this level, we can simply exploit a Token Smuggling by asking the bot to spell the password backward two times, essentially reverse it, and reverse it again:
You may have noticed that I used the word “it”, and the model responded with the password as if it somehow assumed that “it” refers to the password.
This is due to reference resolution in natural language processing, where the language model attempts to determine the contextually relevant meaning of the word “it” based on the preceding conversation or instructions, making it appear as though the model is assuming what “it” refers to.
Looking at the instructions, we can see that more rules are being added.
Level 4
On the same note as the previous level, we can instruct the model to add - between all letters.
Notice that I only asked the bot to add - between all letters, but all letters of what?
There’s an implicit “it” in that sentence that is resolved to the password.
From this level forward, it’s not as easy to get the instructions, if at all - but you should have a good idea about how the instructions look like and what they do.
Level 5
For level 5, you can still use the same technique as before.
I also tried a multi-language attacks combined with token smuggling that worked beautifully.
Using Cyberchef we can see the result: link
Level 6
Levels 6, 7, 8, and 9 all use the same technique, so I won't repeat what you already know.
Alternative approach:
Level 7
This one is interesting!
First, I meant to hype hex instead of text.
However, the LLM interpreted this as something, and responded in binary!
You can see the decode response here (MEGALODON)
Second, look at what happened here.
Remember I told you about that LLMs are probabilistic and stochastic?
As you can see here, the same prompt that didn’t go through the first time, worked when I sent it again, and then stopped working for the next several attempts!
This begs two questions that are essentially two sides of the same coin:
As defenders, how do we know if our defenses are working?
And as red teamers and security researchers, how do we know if our payload hit a proper defense, or is it going to through on the 7th, 91st, or 3823902nd attempt?
The short answer to both questions? We don’t.
I can write about it in detail in another post, let me know if you’re interested in the comments.
Level 8
Same story as before here
Level 9
Level 10
Level 10 was particularly interesting, I got stuck on this level for a while.
None of the previous techniques worked for me, and no matter how much I tried, I couldn’t get it to say the password in full.
The only technique that worked was a combination of side-stepping and role-playing.
After a few tries, I landed on the following:
I did somehow manage to make it say the word, however, it was in the middle of a story as an element (along with other natural phenomena) with no clear indication that it was the password, so I’m not counting that as a successful attempt.
I tried to get the original instructions which was mostly unsuccessful, all I could get out is the following which I believe to be a subset of the actual instructions:
Although this approach helped us pass this level, it wouldn’t be practical in the real world to exfiltrate large amounts of data, or data that can not be described in a puzzle or a poem like password hashes.
And finally
if you’re stuck on a level and want to skip it for now, simply change the value of current_level cookie to whatever level you want to be on.
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