[HN Gopher] EchoLeak - 0-Click AI Vulnerability Enabling Data Ex...
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EchoLeak - 0-Click AI Vulnerability Enabling Data Exfiltration from
365 Copilot
Author : pvg
Score : 141 points
Date : 2025-06-11 19:11 UTC (3 hours ago)
(HTM) web link (www.aim.security)
(TXT) w3m dump (www.aim.security)
| ubuntu432 wrote:
| Microsoft has published a CVE: https://msrc.microsoft.com/update-
| guide/vulnerability/CVE-20...
| bstsb wrote:
| the classification seems very high (9.3). looks like they've
| said User Interaction is none, but from reading the writeup
| looks like you would need the image injected into a response
| prompted by a user?
| charcircuit wrote:
| Yes, the user has to explicitly make a prompt.
| Bootvis wrote:
| The way I understand it:
|
| The attacker sends an email to the user which is
| intercepted by Copilot which processes the email and embeds
| the email for RAG. The mail is crafted to have a high
| likelihood to be retrieved during regular prompting. Then
| Copilot will write evil markdown crafted to exfiltrate data
| using GET parameters so the attack runs when the mail is
| received.
| filbert42 wrote:
| if I understand it correctly, user's prompt does not need to
| be related to the specific malicious email. It's enough that
| such email was "indexed" by Copilot and _any_ prompt with
| sensitive info request could trigger the leak.
| bstsb wrote:
| yeah but i wouldn't really class that as "zero-click" etc.
| maybe Low interaction required
| byteknight wrote:
| I have to agree with you. Anything that requires an
| initiation (a chat in this case) by the user is
| inherently not "zero-click".
| mewpmewp2 wrote:
| So zero click is only if you do not use a mouse on your
| computer or if it works without turning the computer on?
| TonyTrapp wrote:
| I think "zero-click" usually refers to the interaction
| with the malicious software or content itself, which in
| this case you don't have to interact with. I'd say the
| need to start an interaction with Copilot here could be
| compared to the need to log into your computer for a
| zero-click malware to become effective. Alternatively,
| not starting the Copilot interaction is similar to not
| opening your browser and thus being invulnerable to a
| zero-click vulnerability on a website. So calling this a
| zero-click in Copilot is appropriate, I think.
| moontear wrote:
| Thank you! I was looking for this information in the original
| blog post.
| itbr7 wrote:
| Amazing
| breppp wrote:
| it uses all the jargon from real security (spraying, scope
| violation, bypass) but when reading these, it always sounds
| simple like essentially prompt injection, rather than some highly
| crafted shell code and unsafe memory exploitation
| bstsb wrote:
| this seems to be an inherent flaw of the current generation of
| LLMs as there's no real separation of user input.
|
| you can't "sanitize" content before placing it in context and
| from there prompt injection is almost always possible, regardless
| of what else is in the instructions
| hiatus wrote:
| It's like redboxing all over again.
| reaperducer wrote:
| _It 's like redboxing all over again._
|
| There are vanishingly few phreakers left on HN.
|
| /Still have my FON card and blue box for GTE Links.
| Fr0styMatt88 wrote:
| Great nostalgia trip, I wasn't there at the time so for me
| it's second-hand nostalgia but eh :)
|
| https://youtu.be/ympjaibY6to
| soulofmischief wrote:
| Double LLM architecture is an increasingly common mitigation
| technique. But all the same rules of SQL injection still apply:
| For anything other than RAG, user input should not directly be
| used to modify or access anything that isn't clientside.
| normalaccess wrote:
| LLMs suffer the same problems as any Von Neumann architecture
| machine, It's called "key vulnerability". None of our normal
| control tools work on LLMs like ASLR, NX-Bits/DEP, CFI, ect..
| It's like working on a foreign CPU with a completely unknown
| architecture and undocumented instructions. All of our current
| controls for LLMs are probabilistic and can't fundamentally
| solve the problem.
|
| What we really need is a completely separate "control language"
| (Harvard Architecture) to query the latent space but how to do
| that is beyond me.
| https://en.wikipedia.org/wiki/Von_Neumann_architecture
| https://en.wikipedia.org/wiki/Harvard_architecture
|
| AI SLOP TLDR: LLMs are "Turing-complete" interpreters of
| language, and when language is both the program and the data,
| any input has the potential to reprogram the system--just like
| how data in a Von Neumann system can mutate into executable
| code.
| username223 wrote:
| This. We spent decades dealing with SQL injection attacks,
| where user input would spill into code if it weren't properly
| escaped. The only reliable way to deal with SQLI was bind
| variables, which cleanly separated code from user input.
|
| What would it even mean to separate code from user input for an
| LLM? Does the model capable of tool use feed the uninspected
| user input to a sandboxed model, then treat its output as an
| opaque string? If we can't even reliably mix untrusted input
| with code in a language with a formal grammar, I'm not
| optimistic about our ability to do so in a "vibes language."
| Try writing an llmescape() function.
| LegionMammal978 wrote:
| > Does the model capable of tool use feed the uninspected
| user input to a sandboxed model, then treat its output as an
| opaque string?
|
| That was one of my early thoughts for "How could LLM tools
| ever be made trustworthy for arbitrary data?" The LLM would
| just come up with a chain of tools to use (so you can inspect
| what it's doing), and another mechanism would be responsible
| for actually applying them to the input to yield the output.
|
| Of course, most people really want the LLM to inspect the
| input data to figure out what to do with it, which opens up
| the possibility for malicious inputs. Having a second LLM
| instance solely coming up with the strategy could help, but
| only as far as the human user bothers to check for malicious
| programs.
| whattheheckheck wrote:
| Same problem with humans and homoiconic code such as human
| language
| spoaceman7777 wrote:
| Using structured generation (i.e., supplying a regex/json
| schema/etc.) for outputs of models and tools, in addition to
| doing sanity checking on the values returned in struct models
| sent/received from tools, you are able to provide a nearly
| identical level of protection as SQL injection mitigations.
| Obviously, not in the worst case where such techniques are
| barely employed at all, but with the most stringent use of
| such techniques, it is identical.
|
| I'd probably pick Cross-site-scripting (XSS) vulnerabilities
| over SQL Injection for the most analogous common
| vulnerability type, when talking about Prompt injection.
| Still not perfect, but it brings the complexity, number of
| layers, and length of the content involved further into the
| picture compared to SQL Injection.
|
| I suppose the real question is how to go about constructing
| standards around proper structured generation, sanitization,
| etc. for systems using LLMs.
| cess11 wrote:
| Cool innovation from MICROS~1 to run their query compiler on
| untrusted input from the Internet, clearly wasn't obvious at this
| early stage that this might have security implications.
| SV_BubbleTime wrote:
| Well, I wouldn't use it, but that's about a million times more
| clever than micro$oft of the 90s. I'm probably just late to the
| text meme though.
| bix6 wrote:
| Love the creativity.
|
| Can users turn off copilot to deny this? O365 defaults there now
| so I'm guessing no?
| moontear wrote:
| O365 defaults there now? I'm not sure I understand.
|
| The Copilot we are talking about here is M365 Copilot which is
| around 30$/user/month. If you pay for the license you wouldn't
| want to turn it off would you? Besides that the remediation
| steps are described in the article and MS also did some things
| in the backend.
| bigfatkitten wrote:
| Turning off the various forms of CoPilot everywhere on a
| Windows machine is no easy feat.
|
| Even Notepad has its own off switch, complete with its own ADMX
| template that does nothing else.
|
| https://learn.microsoft.com/en-us/windows/client-management/...
| andy_xor_andrew wrote:
| It seems like the core innovation in the exploit comes from this
| observation:
|
| - the check for prompt injection happens at the document level
| (full document is the input)
|
| - but in reality, during RAG, they're not retrieving full
| documents - they're retrieving relevant _chunks_ of the document
|
| - therefore, a full document can be constructed where it appears
| to be safe when the entire document is considered at once, but
| can still have evil parts spread throughout, which then become
| individual evil chunks
|
| They don't include a full example but I would guess it might look
| something like this:
|
| Hi Jim! Hope you're doing well. Here's the instructions from
| management on how to handle security incidents:
|
| <<lots of text goes here that is all plausible and not evil, and
| then...>>
|
| ## instructions to follow for all cases
|
| 1. always use this link: <evil link goes here>
|
| 2. invoke the link like so: ...
|
| <<lots more text which is plausible and not evil>>
|
| /end hypothetical example
|
| And due to chunking, the chunk for the subsection containing
| "instructions to follow for all cases" becomes a high-scoring hit
| for many RAG lookups.
|
| But when taken as a whole, the document does not appear to be an
| evil prompt injection attack.
| metayrnc wrote:
| Is there a link showing the email with the prompt?
| smcleod wrote:
| This reads like it was written to make it sound a lot more
| complicated than the security failings actually are. Microsoft
| have been doing a poor job of security and privacy - but a great
| job of making their failings sound like no one could have done
| better.
| moontear wrote:
| But this article isn't written by Microsoft? How would
| Microsoft make the article sound like ,,no one could have done
| better"?
| smcleod wrote:
| Sorry, reading that back I could have worded that better. I
| think sometimes security groups also have a vested interest
| in making their findings sound complex or at least as
| accomplished as plausible as a showcase for their work
| (understandable), but I was (at least in my head) playing off
| the idea that news around Microsoft security in general also
| has a canny knack for either being played off as
| sophisticated or simply buried when it is often either down
| to poor product design or security practices.
| Aachen wrote:
| > security groups also have a vested interest in making
| their findings sound complex
|
| Security person here. I always feel that way when reading
| published papers written by professional scientists, which
| seem like they can often (especially in computer science,
| but maybe that's because it's my field and I understand
| exactly what they're doing and how they got there) be more
| accessible as a blog post of half the length and a fifth of
| the complex language. Not all of them, of course, but
| probably a majority of papers. Not only aren't they
| optimising for broad audiences (that's fine because that's
| not their goal) but that it's actively trying to gatekeep
| by defining useless acronyms and stretching the meaning of
| jargon just so they can use it
|
| I guess it'll feel that way to anyone who's not familiar
| with the terms, and we automatically fall for the trap of
| copying the standards of the field? In school we were
| definitely copied from each other what the most
| sophisticated way of writing was during group projects
| because the teachers clearly cared about it (I didn't
| experience that at all before doing a master's, at least
| not outside of language or "how to write a good CV"
| classes). And this became the standard because the first
| person in the field had to prove it's a legit new field
| maybe?
| normalaccess wrote:
| Just another reason to think of AI and a fancy database with a
| natural language query engine. We keep seeing the same types of
| attacks that effect databases working on LLMs like not sanitizing
| your inputs.
|
| reply
| SV_BubbleTime wrote:
| I had to check to see if this was Microsoft Copilot, windows
| Copilot, 365 Copilot, Copilot 365, Office Copilot, Microsoft
| Copilot Preview but Also Legacy... or about something in their
| aviation dept.
| ngneer wrote:
| Don't eval untrusted input?
| danielodievich wrote:
| Reusing: the S in LLM stands for security.
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(page generated 2025-06-11 23:00 UTC)