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Ask HN: Crooked Timber showed showed me a virus captcha, What now?

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Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#11
> How do you protect yourself

Was the site itself actually infected(hacked)? If not, then all you need is adblock (like ublock origin). And that was true for last 20 years.

If website actually got hacked then I don't know of any good solutions. It will be flagged soon or later, and new visitors will be blocked by "Google Safe Browsing". Using something like "Qubes OS" might protect you against attacks based on browser zero-days but VMs don't really protect against ClickFix when people usually share clipboard between host and client VMs.

Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#13

This is called a "ClickFix" attack. There is really _never_ a time when a CAPTCHA will require you to execute code on your machine. The attack is basically getting someone to accidentally run malicious code. - ctrl + R brings up the Windows "run" dialogue. - the code executes a powershell command that reaches out to a remote server - if successful, the remote server answers and you have installed a dropper or somethi…

$dayjob just sent out a corporate wide email saying the same thing... I guess it's starting to go around... it's been a while since I've seen a fake website telling people to eg. disable UAC.

Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#14
> Has this happened to you before ?

Almost, recently. I bought a new Mac, needed something reliable to carry around. I never had a Mac or anything from Apple before, so I wasn't familiar with how exactly does it work. I knew homebrew existed, I understood it's similar to Linux/Windows in that not all applications are in the store, but wasn't familiar at all with how those are commonly installed.

Here's what I did:

1. Open Safari, the only browser there was.

2. Typed "claude mac download" in the search bar (needed Cowork).

3. Clicked the first link.

4. Copied the command it told me to, instructing me to run it in terminal.

Only now I realize that there's something fishy about the command; it had base64 payload in it. Didn't run it and took closer look on the page - it was a Claude share (which I quickly scrolled over).

I can admit mistakes, but Google, Apple and Anthropic deserve some blame here, too.

- Google: pushed malware link up top, didn't (distinctly, at least) mark it as a paid result and I'd swear it didn't show me the URL (which I usually always check before clicking, but maybe I just missed it as the search results are rendered differently from Kagi's)

- Safari: hides path by default, so all you see is "claude.ai". Someone probably thought this looked nice, I think it's just borderline idiotic.

- Anthropic: hosts what's essentially a user-content on their main domain.

Also recently saw a few legit projects using base64 in their install one-liners. Please, stop it.

> How do you protect yourself ?

Installed not Safari and made Google not my default search engine, as I always do. That way I at least always know where I am.

Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#15

Not directly answering your questions, but I just wanted to say: Great instincts! You saw something unusual, then 1. Stopped what you were doing. 2. Investigated to see if this was legitimate or malicious. 3. Identified a place to asked others about it. 4. Formulated a good question with enough background information to help people answer it. All around good job! Well done.

5. Paste the entire command on HN so the aspiring script kiddies have a launching point. 6. ? 7. Profit!

Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#16

Not directly answering your questions, but I just wanted to say: Great instincts! You saw something unusual, then 1. Stopped what you were doing. 2. Investigated to see if this was legitimate or malicious. 3. Identified a place to asked others about it. 4. Formulated a good question with enough background information to help people answer it. All around good job! Well done.

5. Put the malicious payload directly into work AI system.

"Great instincts!" lmao

Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#19

This is called a "ClickFix" attack. There is really _never_ a time when a CAPTCHA will require you to execute code on your machine. The attack is basically getting someone to accidentally run malicious code. - ctrl + R brings up the Windows "run" dialogue. - the code executes a powershell command that reaches out to a remote server - if successful, the remote server answers and you have installed a dropper or somethi…

> There is really _never_ a time when a CAPTCHA will require you to execute code on your machine.

I think the concern is the user not knowing they're executing code on their machine.

And as a counterexample: some captchas require you to compute something expensive to prove you're not a llm scraper or whatever. It's normal for captchas to require you to execute code on your machine, it's just usually done within the browser's sandbox.

And anyway, these things are completely incomprehensible to non-technical users.

Re: Ask HN: Crooked Timber showed showed me a virus captcha, What now?

#20
This exact technique has been around for a while; there are even government resources warning about it (e.g. https://www.michigan.gov/msp/divisions/intel-ops/cyber/mc3/c... - April 2025).

As you might imagine, these attacks are aimed at less sophisticated users who may have no idea what Win+R even does, and who might be tricked into believing that this actually has anything to do with website verification.

The site you visited -- or one of the resources it depends on -- might have been compromised. If you're enterprising, you could probably determine where the malicious script is getting loaded from by looking in the page source.

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