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Block Spam Bots With Free CAPTCHA Service 56
Chirag Mehta writes "I just released a freeware service called BotBlock (barebones demo) that lets site owners copy/paste a few lines of PHP code and insert a CAPTCHA image-verification system into any web form. The amount of form spamming by bots is on a rise. While remedies exist for MT blogs, a more efficient solution is to use image-verification or text-identification. Used for a while by sites like Yahoo! (scroll to bottom), Hotmail and patented in 2001 by AltaVista, CAPTCHAs are now being used more widely. PARC also came up with two algorithms Baffletext and Pessimal Print. The technology always existed, but until now required the site owners to install image libraries and understand how to generate images that cannot be OCR'ed. With BotBlock it is like inserting a page counter."
What about blind people? (Score:5, Interesting)
Re:What about blind people? (Score:2, Informative)
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:5, Interesting)
Think those are easy for basic AI bots? Then try them with one of the existing online bots [alicebot.org].
Seems like the problem with this (as opposed to generating pictures) is that it's hard to generate question/answer pairs where there is a one-word or obvious single answer. You don't want to use yes/no questions or questions where the answer is a word in the question ("Which is heavier, lead or cotton?").
Re:What about blind people? (Score:1)
Re:What about blind people? (Score:2)
Terminator 4: Rise of the Spambots (Score:2)
And if they do, the worst they'll do is try to sell us penis enlargement pills, which is still preferable to a Terminator style apocalypse.
Re:What about blind people? (Score:3, Interesting)
I'm afraid I'd have to recommend against using that question for blind people.
Might want to pick your examples a bit more carefully
(Not that it's absolutely impossible they'd know the answer, but it's mere meaningless trivia to someone who has been blind from birth; I don't think I'd remember it.)
Think those are easy f
Re:What about blind people? (Score:2)
which helpful HTML renderers will print in glorious spamavision. (As Slashdot's did until I enclosed the example in an ecode block.)
Your point is well taken. If you come up with a suite of questions. the spa
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:2)
Assigning a high score merely to "bogus" closing tags would be bad too, because of XML. You could score a large number of poorly formed (in the XML sense) tags as suspect. Doing so for only one or two might catch fat-fingered, but otherwise innocent coders. 8)
Re:What about blind people? (Score:2)
This can work at a low level (Score:2)
You (and parent poster) have some good points here. Something you're missing, though -- you're still thinking in terms of a large service that can be reused by lots of websites.
Suppose the system only offered the framework, and you had to provide (and rotate) the questions yourself for your own website. I'm thinking of writing a filter question into my forms, since I hate those text recognition things (my eyesig
Re:This can work at a low level (Score:2)
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:1)
Re:What about blind people? (Score:2)
(Try it on your question. Be sure to type the question precisely.)
What is the perl code for arbitrary questions? The spam programmer doesn't have access to your question. Nobody has programmed a bot that can correctly answer arbitrary question. There is no current way to de-obfuscate (er.. clarify?) this problem. All everybody has to do is write a unique question the a normal person would understand.
Then you are on t
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:2)
Uh, Oh! It's harder than I thought!
Your criticism of generating question/answer pairs is insightful. Don't forget that the bots can also learn to read the pictograms (I think there's a paper on this linked off the captcha.org home page). Whatever type of turing test you come up with, there are likely to be holes in it.
I'm also aware that even a small hole can be just as bad as a big one. I guess the question is whether you can have enough of
Re:What about blind people? (Score:2)
Re:What about blind people? (Score:5, Insightful)
Re:What about blind people? (Score:2)
I really didn't mean to use the same format question and just change the insignificant bits. It just so happens that the examples I chose are bad. I really mean you have to have a supply of question/answer pairs where the answer is obvious and not contained in the question.
That this is a problem only AI can solve has not been demonstrated. It's clear that it's a hard problem, though.
Maybe you could come up with a model for simple things that people understand
Re:What about blind people? (Score:1)
much better (Score:3, Informative)
blacklists are innaccurate: blacklisted words can be misspelled and pass through.
captcha discriminates against the disabled and cuts them off from online discussions.
James Seng has crafted a good bayesian filter for movable type [james.seng.cc].
okay class, pencils down (Score:2, Interesting)
Re:okay class, pencils down (Score:2)
Maybe it could be modified so that only people with >120 IQ can fill in the form too.... hmmmm.....
Re:what about accessibility? (Score:1)
There's two problems with that:
First no alt text is provided in the linked to implimentation.
Secondly, by doing so you've just eliminated the usefulness of the image as a spam bot blocker. I mean, how long would it really take someone to fix up the code on their spam bot to check for alt text and swipe the first letter of each word in it to deal with that kind of situation?
The entire point of the image was that it couldn't be read by machines, by pro
YHBT (Score:1)
The poster knew this. It was either a joke or a troll, or both.
Re:what about accessibility? (Score:1)
Botcheck (Score:2)
Also lots of services, are there any good free downloadable php addons?
Blatent Plug (Score:2, Informative)
http://sourceforge.net/projects/session-captcha/ [sourceforge.net]
Patented? (Score:3, Interesting)
If AltaVista patented it, does BotBlock license the patent? Or will this service be rather short-lived?
Re:Patented? (Score:2)
I'm neither blind nor deaf, but... (Score:2, Interesting)
Re:I'm neither blind nor deaf, but... (Score:2)
Re:I'm neither blind nor deaf, but... (Score:2)
BotBlock looks breakable (Score:1)
Not that I really looked at how configurable this is, but...
...seems to me this BotBlock thingy wouldn't be that hard to decode, juding by the example, at least.
Ssooo, I bet it's feasible to figure out where the codeword starts on the pic. And since the font is easy I guess you can figure out each of the
The new Turing test? (Score:2)
At some point the tests will be so tough and the bots will be so good that many people will be thw
Re:The new Turing test? (Score:2)
Unique CAPTCHA Implementation (Score:3, Informative)
I'm working on another version, which I believe is unique at this point. (At least I didn't find anything like in on Google a few weeks ago).
See a sample at the link below. (DISCLAIMER:: This site is a small self run hosting company, and has "sales" links, and is of commercial nature. So if you're going to get all pissed off because I am trying to feed my kids please do not click through. The sample does not collect or log anything outside of what Apache routinely collects. ) http://webshowhost.com/main.php?smPID=PHP::ui_huma n_verify.php&caseFlag=SAMPLE [webshowhost.com]
What makes this implementation unique is that in the pattern user must identify color and characters. It combines multiple levels of recognition. The user must understand the concept of COLOR and the characters. This should make it particularly difficult for SPAM bots to dicipher, since color is very subjective. I am posting this here mainly to establish prior art (as I have not seen any test use these concepts before) in case some joker tries to patent this variety of CAPTCHA.
My variety integrates into a toolkit I've developed, but basically uses imagemagik montage to fuse pre-rendered image bitmaps into a single JPEG.
It is obviously weak in the sense that it discriminates against blind folks and illiterate folks. On the bright side it has definately eliminated ALL of my spam!
If your interested in this contact me at captcha1@webshowpro.com [mailto] ** Note you'll have to verify yourself with the prototype system to sendmail to that account.
I'll do my best to provide you with the relevent code. I don't have time at this point to lead a project (as my company is a oneman show barely scraping by at this point). So my apologies in advance if I cannot support the code to your satisfaction.
Re:Unique CAPTCHA Implementation (Score:2)
There has not been much demand, so I have not made much progress since my initial tests.
Overall it will be a little weaker i
Re:Unique CAPTCHA Implementation (Score:4, Insightful)
1) Colorblind people (10% of the male population of the world). By far the most common form of colorblindness is red/green, so as long as you stick with easily-distinguished colors like black, red, and blue, you should be fine. You could probably add yellow and a medium grey to the mix, but yellow can be hard for normal people to read, and on some monitors, grey can be mistaken for black.
2) Increase the overlapping of the characters a bit. Right now, the characters can usually be separated out by color into three images, at which point a spambot can simply pick the one that matches the color of the instruction image.
3) You can make an audio CAPTCHA harder for computers to recognize by adding noise to the sound, or by using recordings of a person with a strong accent (or better still, a variety of accents)
Not a perfect solution (Score:4, Insightful)