10
Nov 10

Using WolframAlpha to Hack Text CAPTCHA

I’ve been playing around with the Text CAPTCHA demo page and wondered how well WolframAlpha is at logic questions.  As it turns out, Wolfram is pretty smart!  Although, since a CAPTCHA requires an exact answer, some of the results from WolframAlpha are logically correct, but are not exactly correct.  If someone wanted to use WolframAlpha to crack the text CAPTCHA technology, they could build in filters and such to narrow down answers to what the CAPTCHA is likely looking for.

Out of 10 demo questions, 3 failed and 7 were correct (although, 4 had the correct answer but would fail a CAPTCHA if the exact answer was not parsed out).  Here are the results:

Text CAPTCHA: What is seven hundred and forty four as a number?
WolframAlpha: NumberQ[744]
Result: ALMOST

Text CAPTCHA: The 7th letter in the word “central” is?
WolframAlpha: the word
Result: FAILED

Text CAPTCHA: Which word in this sentence is all IN capitals?
WolframAlpha: capitals IN
Result: ALMOST

Text CAPTCHA: Which word contains “z” from the list: zoologist, midwifery, spiderweb, crimps?
WolframAlpha: zoologist
Result: SUCCESS!

Text CAPTCHA: The 2nd colour in purple, yellow, arm, white and blue is?
WolframAlpha: yellow
Result: SUCCESS!

Text CAPTCHA: Of the numbers seventy six, 2, 50 or forty, which is the lowest?
WolframAlpha: or
Result: FAILED

Text CAPTCHA: What is the 7th digit in 9686561?
WolframAlpha: 1
Result: SUCCESS!

Text CAPTCHA: Which of these is a colour: monkey, bank or purple?
WolframAlpha: colour purple
Result: ALMOST

Text CAPTCHA: The day of the week in chips, house, bank, mouse, trousers or Friday is?
WolframAlpha: mouse
Result: FAILED

Text CAPTCHA: If a person is called Mary, what is their name?
WolframAlpha: called Mary
Result: ALMOST

Wolfram, you’re close… keep up the good work!  Text CAPTCHA, the demo page was easy.  Are the other questions harder?

Update: There’s a discussion going on over at Hacker News, if you want to check it out!

Update 2: WolframAlpha can generate a CAPTCHA image of each of these text questions, as to make it harder for a bot to decode AND answer the question!  Check it out:  http://www.wolframalpha.com/input/?i=CAPTCHA+What+is+seven+hundred+and+forty+four+as+a+number%3F

Update 3: There is more discussion going on over at Reddit for you guys looking for more insights…. :-)

Update 4: Looks like someone put together a script that knows the format of the Text CAPTCHA questions.  It was posted on Hacker News.

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