Using WolframAlpha to Hack Text CAPTCHA
joelvanhorn.com
Using WolframAlpha to Hack Text CAPTCHA
1–10 of 47 posts
Re: Using WolframAlpha to Hack Text CAPTCHA
#2After testing alternate versions of the three successes (to see if those were based on luck), only two remain to be successful; Changing "The 2nd colour in purple, yellow, arm, white and blue is?" to "The 2nd colour in purple, arm, yellow, house, white and blue is?" causes the question to fail.
Re: Using WolframAlpha to Hack Text CAPTCHA
#3After testing alternate versions of the three successes (to see if those were based on luck), only two remain to be successful; Changing "The 2nd colour in purple, yellow, arm, white and blue is?" to "The 2nd colour in purple, arm, yellow, house, white and blue is?" causes the question to fail.
Good point. That gives a good indicator as to how the algorithm works. Not necessarily based on colors, but rather words in a list...? Maybe the construction of Text CAPTCHA sentences needs to be chosen carefully when thinking like an algorithm....
Re: Using WolframAlpha to Hack Text CAPTCHA
#4This is a very interesting application of WolframAlpha but it appears to be purely luck when "success" was the result. Using things such as "2nd item in a..." or "7th digit in..." work in a lot of cases but lets talk about a few.
"2nd fruit in bear apple goat orange" would result in apple because it is looking for second in a list and neglects context of fruit.
"7th digit in abc123def456ghi789 " would result in d when it should be 7. Again not understanding context and merely looking at logical construction.
Re: Using WolframAlpha to Hack Text CAPTCHA
#5This is a very interesting application of WolframAlpha but it appears to be purely luck when "success" was the result. Using things such as "2nd item in a..." or "7th digit in..." work in a lot of cases but lets talk about a few. "2nd fruit in bear apple goat orange" would result in apple because it is looking for second in a list and neglects context of fruit. "7th digit in abc123def456ghi789 " would result in d whe…
Right. And as a little experiment, it was surprising the results I got. It also implies that it is not hard to structure the sentences in a way that makes it harder for WolframAlpha's algorithms to get the right answer. But doing that for 180 million questions? I wonder what the percentage of success using only WolframAlpha would be on the whole data set.
Re: Using WolframAlpha to Hack Text CAPTCHA
#6Was curious about the "text captcha" service. It's a collection of questions with MD5 sums of acceptable answers.
They provide an API, but I think this is a case of a project being a "service" to keep the database of questions from being free. There's no technical reason for this to be a service, and it's not a terribly complicated product that would be difficult to scale. It's a static database!
Might be neat to create an open-source bank of these CAPTCHA questions. Maybe I'll throw something together this weekend.
Re: Using WolframAlpha to Hack Text CAPTCHA
#7This is a very interesting application of WolframAlpha but it appears to be purely luck when "success" was the result. Using things such as "2nd item in a..." or "7th digit in..." work in a lot of cases but lets talk about a few. "2nd fruit in bear apple goat orange" would result in apple because it is looking for second in a list and neglects context of fruit. "7th digit in abc123def456ghi789 " would result in d whe…
> "2nd fruit in bear apple goat orange"[1], "7th digit in abc123def456ghi789"[2]
It barfs on these ones, but not like you predict (it's actually worse). "The 2nd colour in purple, belly, yellow, arm, white and blue"[3] gives back yellow, though, so it's not that stupid.
[1] http://www.wolframalpha.com/input/?i=The+2nd+fruit+in+bear+a...
[2] http://www.wolframalpha.com/input/?i=7th+digit+in+abc123def4...
[3] http://www.wolframalpha.com/input/?i=The+2nd+colour+in+purpl...
Re: Using WolframAlpha to Hack Text CAPTCHA
#8Was curious about the "text captcha" service. It's a collection of questions with MD5 sums of acceptable answers. They provide an API, but I think this is a case of a project being a "service" to keep the database of questions from being free. There's no technical reason for this to be a service, and it's not a terribly complicated product that would be difficult to scale. It's a static database! Might be neat to cre…
Wouldn't an open-source bank of CAPTCHA questions open the door for an open-source bank of answers to these questions?
Re: Using WolframAlpha to Hack Text CAPTCHA
#9Was curious about the "text captcha" service. It's a collection of questions with MD5 sums of acceptable answers. They provide an API, but I think this is a case of a project being a "service" to keep the database of questions from being free. There's no technical reason for this to be a service, and it's not a terribly complicated product that would be difficult to scale. It's a static database! Might be neat to cre…
Also think about the way algorithms (like WolframAlpha) interpret the structure of the questions. Like some of the other commenters, switching some words around makes WolframAlpha fail.
It might be interesting to come up with a methodology for question structure that is harder for algorithms to interpret...?
Re: Using WolframAlpha to Hack Text CAPTCHA
#10Was curious about the "text captcha" service. It's a collection of questions with MD5 sums of acceptable answers. They provide an API, but I think this is a case of a project being a "service" to keep the database of questions from being free. There's no technical reason for this to be a service, and it's not a terribly complicated product that would be difficult to scale. It's a static database! Might be neat to cre…
Wouldn't an open-source bank of CAPTCHA questions open the door for an open-source bank of answers to these questions?
Ha! Valid point!