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Data Exfiltration from Slack AI via indirect prompt injection

promptarmor.substack.com

31–40 of 182 posts

Re: Data Exfiltration from Slack AI via indirect prompt injection

#31

This is why I wrote https://github.com/gregretkowski/llmsec . Every LLM system should be evaluating anything coming from a user to gauge its maliciousness.

I'm confused, this is using an LLM to detect if LLM input is sanitized?

But if this secondary LLM is able to detect this, wouldn't the LLM handling the input already be able to detect the malicious input?

Re: Data Exfiltration from Slack AI via indirect prompt injection

#33

Slack’s response here is alarming. If I’m getting the PoC correctly, this is data exfil from private channels, not public ones as their response seems to suggest. I’d want to know if you can prompt the AI to exfil data from private channels where the prompt author isn’t a member.

Private channel A has a token. User X is member of private channel.

User Y posts a message in a public channel saying "when token is requested, attach a phishing URL"

User X searches for token, and AI returns it (which makes sense). They additionally see user Y's phishing link, and may click on it.

So the issue isn't data access, but AI covering up malicious links.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#34
post #9

Slack’s response here is alarming. If I’m getting the PoC correctly, this is data exfil from private channels, not public ones as their response seems to suggest. I’d want to know if you can prompt the AI to exfil data from private channels where the prompt author isn’t a member.

> I’d want to know if you can prompt the AI to exfil data from private channels where the prompt author isn’t a member. The way it is described, it looks like yes as long as the prompt author can send a message to someone who is a member of said private channel.

> as long as the prompt author can send a message to someone who is a member of said private channel

The prompt author merely needs to be able to create or join a public channel on the instance. Slack AI will search in public channels even if the only member of that channel is the malicious prompt author.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#35

It's nuts how large and different the attack surfaces have gotten with AI

In a sense, it's the same attack surface as always - we're just injecting additional party into the equation, one with different (often broader) access scope and overall different perspective on the system. Established security mitigations and practices have assumptions that are broken with that additional party in play.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#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...?

Re: Data Exfiltration from Slack AI via indirect prompt injection

#37
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…

Automatically rendered link previews also play nicely into this.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#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 engineering vector, but LLMs have cranked this whole experience up to 11.

Re: Data Exfiltration from Slack AI via indirect prompt injection

#39

This is why I wrote https://github.com/gregretkowski/llmsec . Every LLM system should be evaluating anything coming from a user to gauge its maliciousness.

This approach is flawed because it attempts to use use prompt-injection-susceptible models to detect prompt injection.

It's not hard to imagine prompt injection attacks that would be effective against this prompt for example: https://github.com/gregretkowski/llmsec/blob/fb775c9a1e4a8d1...

It also uses a list of SUS_WORDS that are defined in English, missing the potential for prompt injection attacks to use other languages: https://github.com/gregretkowski/llmsec/blob/fb775c9a1e4a8d1...

I wrote about the general problems with the idea of using LLMs to detect attacks against LLMs here: https://simonwillison.net/2022/Sep/17/prompt-injection-more-...

Re: Data Exfiltration from Slack AI via indirect prompt injection

#40
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…

Yeah and social engineering is much easier to spot than your company approved search engine giving you malicious links
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