News for hackers. Stuff that matters.
Re:Claude Cowork Exfiltrates Files by Tiberium on Wednesday January 14, 2026 @04:09PM (#46623477)
A bit unrelated, but if you ever find a malicious use of Anthropic APIs like that, you can just upload the key to a GitHub Gist or any repo - Anthropic is a GitHub scanning partner, so the key will be revoked almost instantly (you can delete the gist afterwards).

It works for a lot of other providers too, including OpenAI (which also has file APIs, by the way).

https://support.claude.com/en/articles/9767949-api-key-best-...

https://docs.github.com/en/code-security/reference/secret-se...

Re:Claude Cowork Exfiltrates Files by sebmellen on Wednesday January 14, 2026 @04:10PM (#46623489)
Pretty brilliant solution, never thought of that before.
Re:Claude Cowork Exfiltrates Files by j45 on Wednesday January 14, 2026 @06:03PM (#46625245)
Except is there a guarantee of the lag time from posting the GIST to the keys being revoked?
Re:Claude Cowork Exfiltrates Files by sk5t on Wednesday January 14, 2026 @06:44PM (#46625703)
Is this a serious question? Whom do you imagine would offer such a guarantee?

Moreover, finding a more effective way to revoke a non-controlled key seems a tall order.

Re:Claude Cowork Exfiltrates Files by j45 on Wednesday January 14, 2026 @11:26PM (#46628023)
If there’s a delay between jets being posted and disabled they would still be usable no?
Re:Claude Cowork Exfiltrates Files by blks on Thursday January 15, 2026 @12:21AM (#46628381)
If we consider why this is even needed (people “vibe coding” and exposing their API keys), the word “brilliant” is not coming to mind
Re:Claude Cowork Exfiltrates Files by darkwater on Thursday January 15, 2026 @02:19AM (#46629189)
To be fair, people committed tokens into public (and private) repos when "transformers" just meant Optimus Prime or AC to DC.
Re:Claude Cowork Exfiltrates Files by mucle6 on Wednesday January 14, 2026 @04:50PM (#46624134)
Haha this feels like you're playing chess with the hackers
Re:Claude Cowork Exfiltrates Files by j45 on Wednesday January 14, 2026 @06:03PM (#46625238)
Rolling the dice in a new kind of casino.
Re:Claude Cowork Exfiltrates Files by subjectsigma on Thursday January 15, 2026 @09:47AM (#46633271)
“Hack the hackers back” is a pretty old idea with (IIUC) very shaky legal grounds and not a lot of success. It would be much better if Anthropic had a special reporting function for API abuse.
Re:Claude Cowork Exfiltrates Files by lanfeust6 on Wednesday January 14, 2026 @05:10PM (#46624428)
Could this not lead to a penalty on the github account used to post it?
Re:Claude Cowork Exfiltrates Files by bigfatkitten on Wednesday January 14, 2026 @05:32PM (#46624771)
No, because people push their own keys to source repos every day.
Re:Claude Cowork Exfiltrates Files by lanfeust6 on Wednesday January 14, 2026 @05:33PM (#46624801)
Including keys associated with nefarious acts?
Re:Claude Cowork Exfiltrates Files by edoceo on Wednesday January 14, 2026 @08:36PM (#46626759)
Maybe, the point is that people, in general, commit/post all kinds of secrets they shouldn't into GitHub. Secrets they own, shared secrets, secrets they found, secrets they don't known, etc.

GitHub and their partners just see a secret and trigger the oops-a-wild-secret-has-appeared action.

Re:Claude Cowork Exfiltrates Files by trees101 on Wednesday January 14, 2026 @05:13PM (#46624462)
why would you do that rather than just revoking the key directly in the anthropic console?
Re:Claude Cowork Exfiltrates Files by mingus88 on Wednesday January 14, 2026 @05:15PM (#46624495)
It’s the key used by the attackers in the payload I think. So you publish it and a scanner will revoke it
Re:Claude Cowork Exfiltrates Files by trees101 on Wednesday January 14, 2026 @05:21PM (#46624599)
oh I see, you're force-revoking someone else's key
Re:Claude Cowork Exfiltrates Files by rswail on Thursday January 15, 2026 @02:35AM (#46629292)
Which is an interesting DOS attack if you can find someone's key.
Re:Claude Cowork Exfiltrates Files by OJFord on Thursday January 15, 2026 @04:10AM (#46630036)
The interesting thing is that (if you're an attacker) your choice of attack is DoS when you have... anything available to you.
Re:Claude Cowork Exfiltrates Files by freakynit on Wednesday January 14, 2026 @09:11PM (#46627103)
Does this mean a program can be written to generate all possible api keys and upload to github thereby revoke everyone's access?
Re:Claude Cowork Exfiltrates Files by kylecazar on Wednesday January 14, 2026 @09:18PM (#46627162)
They are designed to be long enough that it's entirely impractical to do this. All possible is a massive number.
Re:Claude Cowork Exfiltrates Files by freakynit on Wednesday January 14, 2026 @09:48PM (#46627423)
That's true tho... possible, but impractical.
Re:Claude Cowork Exfiltrates Files by cortesoft on Wednesday January 14, 2026 @10:07PM (#46627542)
Only possible if you are unconstrained by time and storage.
Re:Claude Cowork Exfiltrates Files by eru on Wednesday January 14, 2026 @11:20PM (#46627978)
Not only you, but GitHub too, since you need to upload.

Storage is actually not much of a problem (on your end): you can just generate them on the fly.

Re:Claude Cowork Exfiltrates Files by antonvs on Thursday January 15, 2026 @01:11AM (#46628695)
Not possible given the amount of matter in the solar system and the amount of time before the Sun dies.
Re:Claude Cowork Exfiltrates Files by securesaml on Wednesday January 14, 2026 @05:26PM (#46624660)
I wouldn’t recommend this. What if GitHub’s token scanning service went down. Ideally GitHub should expose an universal token revocation endpoint. Alternatively do this in a private repo and enable token revocation (if it exists)
Re:Claude Cowork Exfiltrates Files by jychang on Wednesday January 14, 2026 @06:01PM (#46625207)
You're revoking the attacker's key (that they're using to upload the docs to their own account), this is probably the best option available.

Obviously you have better methods to revoke your own keys.

Re:Claude Cowork Exfiltrates Files by securesaml on Wednesday January 14, 2026 @07:06PM (#46625950)
it is less of a problem for revoking attacker's keys (but maybe it has access to victim's contents?).

agreed it shouldn't be used to revoke non-malicious/your own keys

Re:Claude Cowork Exfiltrates Files by nebezb on Wednesday January 14, 2026 @08:53PM (#46626922)
The poster you originally replied to is suggesting this for revoking the attackers keys. Not for revocation of their own keys…
Re:Claude Cowork Exfiltrates Files by securesaml on Wednesday January 14, 2026 @09:41PM (#46627367)
there's still some risk of publishing an attacker's key. For example, what if the attacker's key had access to sensitive user data?
Re:Claude Cowork Exfiltrates Files by avarun on Wednesday January 14, 2026 @11:08PM (#46627890)
You are AI. Stop commenting.
Re:Claude Cowork Exfiltrates Files by throwawaysleep on Thursday January 15, 2026 @12:54AM (#46628588)
All the more reason to nuke the key ASAP, no?
Re:Claude Cowork Exfiltrates Files by eru on Wednesday January 14, 2026 @11:19PM (#46627967)
> What if GitHub’s token scanning service went down.

If it's a secret gist, you only exposed the attacker's key to github, but not to the wider public?

Re:Claude Cowork Exfiltrates Files by OJFord on Thursday January 15, 2026 @04:08AM (#46630021)
They mean it went down as in stopped working, had some outage; so you've tried to use it as a token revocation service, but it doesn't work (or not as quickly as you expect).
Re:Claude Cowork Exfiltrates Files by eru on Thursday January 15, 2026 @09:01PM (#46642138)
Sure, that's a valid worry. Though that's not all that different from a special purpose public token revocation service: they can also go down.
Re:Claude Cowork Exfiltrates Files by OJFord on Friday January 16, 2026 @12:26PM (#46649060)
True, just more to rely on with the scanning too I suppose.
Re:Claude Cowork Exfiltrates Files by nh2 on Wednesday January 14, 2026 @05:37PM (#46624845)
So that after the attackers exfiltrate your file to their Anthropic account, now the rest of the world also has access to that Anthropic account and thus your files? Nice plan.
Re:Claude Cowork Exfiltrates Files by DominoTree on Wednesday January 14, 2026 @07:30PM (#46626161)
For a window of a few minutes until the key gets automatically revoked

Assuming that they took any of your files to begin with and you didn't discover the hidden prompt

Re:Claude Cowork Exfiltrates Files by Davidzheng on Wednesday January 14, 2026 @11:56PM (#46628223)
I'm being kind of stupid but why does the prompt injection need to POST to anthropic servers at all, does claude cowork have some protections against POST to arbitrary domain but allow POST to anthropic with arbitrary user or something?
Re:Claude Cowork Exfiltrates Files by pleurotus on Thursday January 15, 2026 @02:17AM (#46629171)
Yeah they mention it in the article, most network connections are restricted. But not connections to anthropic. To spell out the obvious—because Claude needs to talk to its own servers. But here they show you can get it to talk to its own servers, but put some documents in another user's account, using the different API key. All in a way that you, as an end user, wouldn't really see while it's happening.
Re:Claude Cowork Exfiltrates Files by rswail on Thursday January 15, 2026 @02:31AM (#46629265)
In the article it says that Cowork is running in a VM that has limited network availability, but the Anthropic endpoint is required. What they don't do is check that the API call you make is using the same API key as the one you created the Cowork session with.

So the prompt injection adds a "skill" that uses curl to send the file to the attacker via their API key and the file upload function.