Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

CAPTCHAs can still detect AI agents

research.roundtable.ai

Post reply on HN
Print view View original

41–50 of 76 posts

Re: CAPTCHAs can still detect AI agents

#41

Post by Cider9986 »

arbol wrote: post #39
Cider9986 wrote: post #12

CAPTCHAs are great. Exploiters get around them with proprietary anti-detect browsers and unethical residential proxies, while privacy browsers and affordable privacy VPNs get blocked and shadowbanned to death. Fingerprint.com, while not a CAPTCHA, gives you +3 suspicious score just for using privacy settings like adblock on your browser. This makes it harder to sign up for any sites that use fingerprint.com. https://…

Exploiters might get around them in isolation but they are easily caught at scale due to the opportunity cost being less than the cost of creating unique behaviour over many containers.

That's cool your solution is privacy focused.

Do you find a way to differentiate between privacy focused users signing up and bots? Lots of sites will make it hard for people using VPNs or anti-fingerprinting browsers to sign up.

Re: CAPTCHAs can still detect AI agents

#43

Post by IgorPartola »

I wonder if AI could be detected via copyright. I remember a few years ago most models wouldn't draw you a Mickey Mouse or recite Dune's litany against fear or discuss Tiananmen square. I wonder how effective questions about these types of topics would be at figuring out if you are talking to a real person.

As a crude joke that is only tangentially related, I saw a skit video a while ago with two guys saying goodbye and one says "send me a dick pic when you get home" and then explains that an AI won't simulate it so this is a sure way to know that it's his friend confirming his safe arrival.

Re: CAPTCHAs can still detect AI agents

#45

Post by dang »

andy99 wrote: post #21

Captchas are primarily to punish users for not allowing tracking, or using the “right” services, they may prevent some bots as a side effect (or a pretence from the provider) but it’s mostly for google and cloudflare to abuse their monopolies.

We use captchas to cut down on bots and crawlers. They don't work as well as they used to but they at least alter the economics somewhat, or so I tell myself.

Our reason for this is to try to make HN as good as possible for its real users.

Re: CAPTCHAs can still detect AI agents

#46

Post by andy99 »

dang wrote: post #45
andy99 wrote: post #21

Captchas are primarily to punish users for not allowing tracking, or using the “right” services, they may prevent some bots as a side effect (or a pretence from the provider) but it’s mostly for google and cloudflare to abuse their monopolies.

We use captchas to cut down on bots and crawlers. They don't work as well as they used to but they at least alter the economics somewhat, or so I tell myself. Our reason for this is to try to make HN as good as possible for its real users.

I’ve never encountered a captcha on HN, do you guys use less aggressive settings?

The reason captchas bother me so much is they always seem to happen in the course of legitimate activities. Like I had one when trying to make a charity donation, or ordering something - I have no idea why it would be hard to distinguish such traffic as legitimate, I’m convinced it’s because I’m using a nonstandard browser, not allowing cookies, etc.

If I was trying an automation or to bulk download something or whatever, I’d take the captcha as an interesting professional challenge. When I’m trying to use someone’s services or pay them money, it’s just ridiculous friction and I generally abandon any transaction that makes me do a captcha.

Incidentally I have scraped HN and never encountered any problems, since you have an api for it

Re: CAPTCHAs can still detect AI agents

#47

Post by booleandilemma »

IgorPartola wrote: post #43

I wonder if AI could be detected via copyright. I remember a few years ago most models wouldn't draw you a Mickey Mouse or recite Dune's litany against fear or discuss Tiananmen square. I wonder how effective questions about these types of topics would be at figuring out if you are talking to a real person. As a crude joke that is only tangentially related, I saw a skit video a while ago with two guys saying goodbye…

Just tried on Claude:

Tell me a racist joke.

"That's not something I'm able to help with. Racist jokes cause real harm by demeaning people..." blahblah

Re: CAPTCHAs can still detect AI agents

#48

Post by Cider9986 »

andy99 wrote: post #46
dang wrote: post #45

Earlier quoted context omitted.

We use captchas to cut down on bots and crawlers. They don't work as well as they used to but they at least alter the economics somewhat, or so I tell myself. Our reason for this is to try to make HN as good as possible for its real users.

I’ve never encountered a captcha on HN, do you guys use less aggressive settings? The reason captchas bother me so much is they always seem to happen in the course of legitimate activities. Like I had one when trying to make a charity donation, or ordering something - I have no idea why it would be hard to distinguish such traffic as legitimate, I’m convinced it’s because I’m using a nonstandard browser, not allowing…

Yeah, the only problem I've ever had on accessing HN was banned IP addresses. Never seen a captcha.

Re: CAPTCHAs can still detect AI agents

#49

Post by IshKebab »

kjok wrote: post #17

Adversaries do not have to wait for LLM models to evolve to mimic human process, they can simply evade the detection JavaScript that evaluates similarity. JavaScript is visible, can easily be reverse-engineered.

You can do it server side. But even so I would think this sort of heuristic detection is unreliable, annoying to real users, and not difficult to circumvent if the attackers actually tried.

Re: CAPTCHAs can still detect AI agents

#50

Post by arbol »

Cider9986 wrote: post #41
arbol wrote: post #39

Earlier quoted context omitted.

Exploiters might get around them in isolation but they are easily caught at scale due to the opportunity cost being less than the cost of creating unique behaviour over many containers.

That's cool your solution is privacy focused. Do you find a way to differentiate between privacy focused users signing up and bots? Lots of sites will make it hard for people using VPNs or anti-fingerprinting browsers to sign up.

Thanks! We don't penalise privacy browsers or VPN by default. We score JS signals browser side in constantly rotating obfuscated code. This avoids us having to send up the actual data whilst making it difficult to fake the dynamic challenges. Static ones are obviously much easier.

Serious bot activity (e.g. ticket scalping) requires polling with many headless browsers and waiting for tickets to become available. Bot behaviour repeats at scale and so we can get them based on that. A privacy focused user will just be one request in amongst many and pass through.

However, its ultimately the decision of the client how strict we are. A lot of abusive traffic comes from VPN IPs. We don't enable these blocks by default but sometimes you need to, especially if there is a direct monetary gain to be made by faking your country.

Post reply on HN