Capturing a "captcha generator" image

Posted on 2008-11-17
Last Modified: 2012-05-05
I work for a company that does online marketing.

One of the things we do is submit our clients to various web directories.

Part of what we do is pull-in a web page and attempt to determine which image is the captcha image (anti-spam text).

One type of image that is particularly resistant to this process is what I call a "captcha generator" where the image that is displayed to the user is based upon a hash.  

For example, if I go to a directory submission page that is using such a process for captchas, I can see the image.  But if I copy the path to the image and try and see the image that way, I get a message saying "Could not fetch image phrase!!" or some such:

But, if you go to the actual submission page, the captcha works:

This is not a problem.  I mean, we are not trying to automatically defeat the captcha -- just capture an image which is representative of the captcha image to display to the end-user who is processing the page.

Since I cannot visit the image directly, since the only way to see it is on the submission page  (after it has rendered) -- my question is -- is there a way to capture the captcha image on the submission page somehow...perhaps by catching the image as it comes in as an HTTP response, or by some form of screen scraping?  But I need sample source code ... particularly for captcha images that use a hash like the above example.

Again - this is not so that we can defeat the captcha image via OCR.  It is just so that we can present the image to the end-user for selection.  It need not even be the image that loads with the page originally.  It could be an image from a page refresh if need be.

This would be happening on an ASP .NET page.

Thank you,

Question by:knowlton
    1 Comment
    LVL 29

    Accepted Solution

    Hi knowlton,
    There are a lot of captcha control that available to download in internet nowaday. Perhaps you can evaluate this captcha control based on the the application. This control is using GID and it similiar with what you're looking. It's working fine for my various managed projects. I hope it will be useful for you too:

    Download source with description included:

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    Featured Post

    Threat Intelligence Starter Resources

    Integrating threat intelligence can be challenging, and not all companies are ready. These resources can help you build awareness and prepare for defense.

    In this Article, I will provide a few tips in problem and solution manner. Opening an ASPX page in Visual studio 2003 is very slow. To make it fast, please do follow below steps:   Open the Solution/Project. Right click the ASPX file to b…
    It was really hard time for me to get the understanding of Delegates in C#. I went through many websites and articles but I found them very clumsy. After going through those sites, I noted down the points in a easy way so here I am sharing that unde…
    This video discusses moving either the default database or any database to a new volume.
    Excel styles will make formatting consistent and let you apply and change formatting faster. In this tutorial, you'll learn how to use Excel's built-in styles, how to modify styles, and how to create your own. You'll also learn how to use your custo…

    779 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    11 Experts available now in Live!

    Get 1:1 Help Now