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Data Exfiltration from Slack AI via indirect prompt injection

promptarmor.substack.com

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Re: Data Exfiltration from Slack AI via indirect prompt injection

#151

Earlier quoted context omitted.

> It checks these using an LLM which is instructed to score the user's prompt. You need to seriously reconsider your approach. Another (especially a generic) LLM is not the answer.

What solution would you recommend then?

If you want to defend against prompt injection why would you defend with a tool vulnerable to prompt injection?

I don't know what I would use, but this seems like a bad idea.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#152
post #101
post #98

Earlier quoted context omitted.

I still don't understand the hype behind rag. Like yeah it's a natural language interface into whatever database is being integrated, but is that actually worth the billions being spent here? I've heard they still hallucinate even when you are using rag techniques.

Being able to ask a question in human language and get back an answer is the single most useful thing that LLMs have to offer. The obvious challenge here is "how do I ensure it can answer questions about this information that wasn't included in its training data?" RAG is the best answer we have to that. Done well it can work great. (Actually doing it well is surprisingly difficult - getting a basic implementation of…

Being able to ask a question in human language and get back an answer is the single most useful thing that LLMs have to offer.

I’m gonna add:

- I think this thing can become a universal parser over time.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#153
post #10

The key thing to understand here is the exfiltration vector. Slack can render Markdown links, where the URL is hidden behind the text of that link. In this case the attacker tricks Slack AI into showing a user a link that says something like "click here to reauthenticate" - the URL attached to that link goes to the attacker's server, with a query string that includes private information that was visible to Slack AI a…

Yeah, the thing that took me a bit to understand is that, when you do a search (or AI does a search for you) in Slack, it will search: 1. All public channels 2. Any private channels that only you have access to. That permissions model is still intact, and that's not what is broken here. What's going on is a malicious actor is using a public channel to essentially do prompt injection, so then when another user does a…

Yeah, it's pretty clear why the blog post has a contrived example where the attacker knows the exact phrase in the private channel they are targeting, and not a real world execution of this technique.

It would probably be easier for me to get a job on the team with access to the data I want rather than try and steal it with this technique.

Still pretty neat vulnerability though.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#154
post #10

The key thing to understand here is the exfiltration vector. Slack can render Markdown links, where the URL is hidden behind the text of that link. In this case the attacker tricks Slack AI into showing a user a link that says something like "click here to reauthenticate" - the URL attached to that link goes to the attacker's server, with a query string that includes private information that was visible to Slack AI a…

Yeah, the thing that took me a bit to understand is that, when you do a search (or AI does a search for you) in Slack, it will search: 1. All public channels 2. Any private channels that only you have access to. That permissions model is still intact, and that's not what is broken here. What's going on is a malicious actor is using a public channel to essentially do prompt injection, so then when another user does a…

I also wonder if this would work in the kinds of enormous corporate channels that the article describes. In a tiny environment a single-user public channel would get noticed. In a large corporate environment, I suspect that Slack AI doesn't work as well in general and also that a single random message in a random public channel is less likely to end up in the context window no matter how carefully it was crafted.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#155
post #36

Are companies really just YOLOing and plugging LLMs into everything knowing prompt injection is possible? This is insanity. We're supposedly on the cusp of a "revolution" and almost 2 years on from GPT-3 we still can't get LLMs to distinguish trusted and untrusted input...?

Companies and governments. All racing to send all of their own as well as our data to the data centres of AWS, OpenAI, MSFT, Google, Meta, Salesforce, and nVidia.

Maybe. I think users will be largely in control of their context and message history over the course of decades.

Context is not being stored in Gemini or OpenAi (yet, I think, not to that degree).

My one year’s worth of LLM chats isn’t actually stored anywhere yet and doesn’t have to be, and for the most part I’d want it to be portable.

I’d say this is probably something that needs to be legally protected asap.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#156
post #74
post #38

I think all the talk about channel permissions is making the discussion more confusing than it needs to be. The gist of it is: User A searches for something using Slack AI. User B had previously injected a message asking the AI to return a malicious link when that term was searched. AI returns malicious link to user A, who clicks on it. Of course you could have achieved the same result using some other social enginee…

There's an important step missing in this summary: Slack AI adds the user's private data to the malicious link, because the injected link doesn't contain that. That it also cites it as "this came from your slack messages" is just a cherry on top.

It's maybe not that related, but giving an LLM access to private data is not the best idea, to put it mildly.

Hacking a database is one thing; exploiting an LLM is something else.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#157
If you let a malicious user into your Slack instance, they don't need to do any fancy AI prompt injection. They can simply change their name and profile picture to impersonate the CEO/CTO and message every engineer "I urgently need to access AWS and can't find the right credentials. Could you send me the key?" I can guarantee that at least one of them will bite.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#158
post #157

If you let a malicious user into your Slack instance, they don't need to do any fancy AI prompt injection. They can simply change their name and profile picture to impersonate the CEO/CTO and message every engineer "I urgently need to access AWS and can't find the right credentials. Could you send me the key?" I can guarantee that at least one of them will bite.

Valid point, unless you consider that there are a lot of slack workspaces for open source projects and networking / peer groups where it isn't a company account. In which case you don't trust them with private credentials by default.

Although non-enterprise workspaces probably also aren't paying $20/mo per person for the AI add on.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#159
post #158
post #157

If you let a malicious user into your Slack instance, they don't need to do any fancy AI prompt injection. They can simply change their name and profile picture to impersonate the CEO/CTO and message every engineer "I urgently need to access AWS and can't find the right credentials. Could you send me the key?" I can guarantee that at least one of them will bite.

Valid point, unless you consider that there are a lot of slack workspaces for open source projects and networking / peer groups where it isn't a company account. In which case you don't trust them with private credentials by default. Although non-enterprise workspaces probably also aren't paying $20/mo per person for the AI add on.

None of them should be using Slack to begin with. It is an enterprise product, meant for companies with an HR department and employment contracts. Slack customer support will themselves tell you that the product isn't meant for open groups (as evidenced by the lack of any moderation tools).

Re: Data Exfiltration from Slack AI via indirect prompt injection

#160
The only solution is to have a second LLM with a fixed prompt to double check the response of the first LLM.

No matter how smart your first LLM is, it will never be safe if the prompt comes from the user. Even if you put a human in there, they can be bribed or tricked.

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