This project also solves the 4chan captcha https://github.com/moffatman/chan
Breaking the 4Chan CAPTCHA
31–40 of 378 posts
Re: Breaking the 4Chan CAPTCHA
#32Earlier quoted context omitted.
Yeah, I encountered those as well in my data gathering. I threw them out from the training set, but I kept them for possible future experimentation.
Can you upload a few of these samples somewhere?
I need to manipulate the data a bit, because right now it's just raw, unaligned foreground/background images with solutions. I need to do the alignment and save them as images rather than JSON files. I'll do that when I have the time.
Re: Breaking the 4Chan CAPTCHA
#33It might be worth noting that this, including the harder version the op encountered, are not the hardest captchas that 4chan can serve. There is a still harder version which is sent to less trustworthy IPs. I imagine it would still be tractably solved with computer vision. This in part misses the point though, since 4chan has been continuously altering their captcha since it released, making it difficult to create a…
Datacenter IPs can’t even post at all, nevermind needing to solve a CAPTCHA. That’s why the accusations of “VPN shill” are usually wrong, as is the assumption of anonymity – 4chan is in fact one of the least anonymous sites on the internet. The optional username feature gives it a veneer of anonymity, but the strict IP requirements ensure almost every post is attributable to a residential internet connection, and rel…
What about users behind CGNAT, like mobile users?
Re: Breaking the 4Chan CAPTCHA
#34Earlier quoted context omitted.
Datacenter IPs can’t even post at all, nevermind needing to solve a CAPTCHA. That’s why the accusations of “VPN shill” are usually wrong, as is the assumption of anonymity – 4chan is in fact one of the least anonymous sites on the internet. The optional username feature gives it a veneer of anonymity, but the strict IP requirements ensure almost every post is attributable to a residential internet connection, and rel…
What about users behind CGNAT, like mobile users?
That’s attributable with the right warrant and correlation with other data available to the ISP.
CGNAT is not an anonymity mechanism – at best it may be a very crude one, but the carriers will make extra effort to remove that anonymity through logging, retention, and segmentation.
Re: Breaking the 4Chan CAPTCHA
#35I've built 3 iterations of captcha solvers for that crappy website based on https://github.com/drunohazarb/4chan-captcha-solver/issues/1 . The only thing I've learned along the way is that it's mostly pointless outside of a "learning" exercise, since they'll change the captcha (in terms of letter count or the entropy background). Initially, it was 4 characters with pretty obvious background, then it turned to 5, then it was both 4 and 5 and the current iteration which is also either 4 or 5, but with a lot of entropy surrounding the characters.
Re: Breaking the 4Chan CAPTCHA
#36Earlier quoted context omitted.
Datacenter IPs can’t even post at all, nevermind needing to solve a CAPTCHA. That’s why the accusations of “VPN shill” are usually wrong, as is the assumption of anonymity – 4chan is in fact one of the least anonymous sites on the internet. The optional username feature gives it a veneer of anonymity, but the strict IP requirements ensure almost every post is attributable to a residential internet connection, and rel…
Some datacenter IPs can post fine, mostly just not those belonging to any large hosting company. I would mention a list of ones I know aren't blocked, but, well, that might get them blocked.
That’s surprising to me. I assumed they were using some service (like Cloudflare) with an updated list of non-residential IP addresses.
I’ve only ever tried to post through Cloudflare WARP (or Apple Private Relay, which is also Cloudflare but different exit IP range). Once I realized that didn’t work, I thought maybe it wasn’t worth posting at all :) I don’t like the idea of my ISP having any suspicion I posted to 4Chan (even if it’s technically https yadda yadda…)
Re: Breaking the 4Chan CAPTCHA
#37Earlier quoted context omitted.
Datacenter IPs can’t even post at all, nevermind needing to solve a CAPTCHA. That’s why the accusations of “VPN shill” are usually wrong, as is the assumption of anonymity – 4chan is in fact one of the least anonymous sites on the internet. The optional username feature gives it a veneer of anonymity, but the strict IP requirements ensure almost every post is attributable to a residential internet connection, and rel…
What about users behind CGNAT, like mobile users?
"Attributable" means by law enforcement, and mobile carriers, like all ISPs, must keep logs. In this case, for who had which IP address when.
(Otherwise, it's akin to the usual confusion between anonymity and pseudonymity.)
Re: Breaking the 4Chan CAPTCHA
#38Earlier quoted context omitted.
What about users behind CGNAT, like mobile users?
"Attributable" means by law enforcement, and mobile carriers, like all ISPs, must keep logs. In this case, for who had which IP address when. (Otherwise, it's akin to the usual confusion between anonymity and pseudonymity.)
That’s true, but to be fair my original comment also said posts would be reliably associable with other posts from the same IP. With CGNAT, that association will be slightly less reliable, but not meaningfully so. The segment of the population who posts on 4chan is so low that there is negligible chance of two 4chan users sharing an exit IP and time window. Even with non-overlapping time windows, the population will be low enough for stylometry (and other factors) to remove any remaining ambiguity.
Re: Breaking the 4Chan CAPTCHA
#39I've built 3 iterations of captcha solvers for that crappy website based on https://github.com/drunohazarb/4chan-captcha-solver/issues/1 . The only thing I've learned along the way is that it's mostly pointless outside of a "learning" exercise, since they'll change the captcha (in terms of letter count or the entropy background). Initially, it was 4 characters with pretty obvious background, then it turned to 5, then…
In the article it mentions they changed the number of characters in the captcha after he trained the model, and the model could still solve it
Re: Breaking the 4Chan CAPTCHA
#40I've built 3 iterations of captcha solvers for that crappy website based on https://github.com/drunohazarb/4chan-captcha-solver/issues/1 . The only thing I've learned along the way is that it's mostly pointless outside of a "learning" exercise, since they'll change the captcha (in terms of letter count or the entropy background). Initially, it was 4 characters with pretty obvious background, then it turned to 5, then…
This project was really my first decent introduction to computer vision and machine learning (along with that of those who helped me in various ways; none of them desired to be credited here other than the guy who collected some of the data for me.)
It was definitely a successful learning exercise, and it's made me more confident tackling some other problems I've had in mind for awhile.