This reads to me as "user installed exe file can upload your data to a server". Um, yes, that's the point?
This seems like this generation's equivalent of "don't open Linkin-Park.mp3.exe from limewire"
I'm not going to defend Microsoft here, but the title (at the source blog) is misleading and a bit rage-baity. What happened with Cowork may have been rushed, possibly due to incompetence, but incompetence is not malice. This framing is also recycled across a few of the author's other interesting findings.
Within the article, the wording is much more accurate: “The victim uploads a skill file to Copilot Cowork that contains a prompt injection,” and “The injection manipulates Microsoft Copilot Cowork into posting a Teams message that exfiltrates pre-authenticated file download links when viewed.”
it's indeed accurate and clearly states what the outcome is: an exfiltration. why is it misleading to say so in the title?
it's pretty obvious that it means that "cowork" is the component vulnerable to exfiltration, not the prime actor.
This is an intrinsic risk associated with giving LLMs access to sensitive material. It's reckless of Microsoft to give an LLM such broad access based on the user's own permissions.
If there were a confirmation prompt for the Teams message, why would even a highly competent user refuse it? That's what the skill says it will do. The message is expected, the visible content is expected, a confirmation prompt is just a nuisance.
OpenAI released their LLM-driven browser Atlas last year. Though their team is brilliant (https://openai.com/index/hardening-atlas-against-prompt-inje...), there has been a number of succeeded injection attacks.
IMO the real vulnerability is located at the "Act" part of "ReAct" (reasoning and action) agent framework.
> “[Copilot] Cowork asks for your permission before taking sensitive actions...” ... when the recipient is the active user, these actions execute immediately without requiring human approval (users do not have a setting to modify this behavior).
> Copilot Cowork can retrieve ‘pre-authenticated download links’ for files the user has access to, which allow anyone who opens the link to download that file.
> Microsoft Copilot Cowork has read access to essentially any resource a user does through Microsoft Graph. As such, the primary mechanism to reduce the blast radius of attacks like this is to restrict excessive permissioning across one’s Microsoft ecosystem.
Take it easy. Inside the whole attack flow, Microsoft gives Cowork unrestricted access and the ability to bypass approvals. I don't find much problem with LLMs here. It's said the attack is also a threat for Opus 4.7, but I've found several times Opus 4.7 forbidding context7.com's "prompt injections" only requiring opus to ask me creating an context7 API key to get more requests for free. From my personal experience, such models indeed are trained to perceive injections, but these injections could mask themselves as sth like Agent Skills, and there are always ways to win as red teams.
We may not lay our hope too much on defense of injections, but concentrating on restricting LLM's permissions. The popular usage of CLIs in agents' (especially coding agents) workflow has also concerned me since most cli tools an agent can access actually have the same permissions with users.
This is a fancy way of saying that “the problem is tool calling”, which is obviously true. The problem is that, when it works correctly (99.99% of the time), it adds so much more value to LLMs.
Sandboxing is a step in the right direction, but can also add friction.
Using guardrails is also good, but adds latency, expenses, and also doesn’t solve 100% of the issues.
IMHO there currently does not exist a proper solution to this problem, and it has yet to be discovered. The proper solution, however, should NOT be based on LLMs, so guardrails are the incorrect direction (albeit effective and easier to implement).
Yes I'm a builder of an agent infra on PCs, so I can completely sense that the protective measures are weak and inadequate, sometimes seeming like an unsolvable problem. But according to the article, what Microsoft did was hard to tell in a polite way. If they had even a little security awareness, I could completely understand, but it's like they've vibe coded the entire permissions system of Cowork.
They have no taste. And no aspiration to taste. The industry is moving too quickly for the quasi-monopoly strategy of forcing users to buy their product.
Books will be written about how Microsoft had an amazing strategic position and failed at AI because they never prioritized an actual great product.
The combo of rushing with a technology that isn't very easy to control, understand or securely limit is just mad to me.
I think this isn't surprising, nor do I think it should be considered a prompt injection at all. An AI skill is akin to a plugin for traditional software - if you install a malicious IDE extension or Outlook plugin, the attacker can also do whatever they want to the PC and exfiltrate whatever data they want to. So this article is a big nothingburger.
And it was expired!
And I was happy. And some time passed - and I realized it had read my .env file and performed operations on my API keys.
That these models do all this stuff already makes me assume any skill take over is simply trivial.
Or if it has access to a tool call which allows it to exfiltrate data.
In the example identified, the AI agent never accesses the exfiltration URL.
The agent sends an innocuous-looking message to a user via a teams message.
MSTeams previews the link, accessing the exfiltration URL.
Can we stop the apologetic framing? It's increasingly common to create exploits from multiple vulnerabilities. Each one is bad. Downloading corporate malware is stupid. Adding random prompt injection is reckless. Insane to run autonomous agents on top of it.
Prompt injection is more serious in this regard, because there is no known solid protection. All the other problems are failure in process, prompt injection is failure at the first thought.
> Note: Admins have limited oversight of ‘Skills’, as Skills in Copilot Cowork are automatically loaded from a specific path in a user’s OneDrive.
I feel this part is a bit disingenuous. We have full control over the sharepoint containers which house users personal onedrives. We actively scan them and prevent a lot of files from getting in them. That being said, it's still a fair point, because a "skill" could basically be a text file.
Here's my repo for running copilot in a vm
github.com/gokuvegeta894/node-copilot-vm
(Fake link, if someone typosquats the above link and it exists, assume it's malware)