Help solving SVG based captcha. #65

cp1797 · 2021-05-11T10:38:52Z

Please provide at least 10 example images of the CAPTCHA system:

Please provide the full JavaScript source to what you've already tried:

var cbl = new CBL({
            preprocess: function(img) {
				img.invert(1);
                img.debugImage("debugPreprocessed");
				img.binarize(240);                
				img.debugImage("debugPreprocessed");
                img.colorRegions(0);
                img.debugImage("debugPreprocessed");
            },
            character_set: "abcdefghijklomnpqrtsuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789",
            blob_min_pixels: 50,
            blob_max_pixels: 400,
            pattern_width: 30,
            pattern_height: 40,
            allow_console_log: true,
            perceptive_colorspace: true,
            blob_debug: "debugSegmented"
        });

The text was updated successfully, but these errors were encountered:

skotz · 2021-05-11T13:33:11Z

The examples came through as PNGs, but if it's really an SVG then you can probably solve it super simply by parsing the path data out of it directly. It doesn't even look like there's any distortion. Do you have an example of the SVG format itself?

skotz · 2021-05-11T14:46:37Z

You can provide them in this thread. If it's converting them to png on you, then open one with a text editor and copy the contents into a code block.

jimmylannister · 2021-05-11T16:24:12Z

jimmylannister · 2021-05-11T16:24:36Z

jimmylannister · 2021-05-11T16:25:32Z

Hi I am unable to upload sag directly. But here's the solution.
It would be awesome if I could console.log the output to the browser too.
Tried the above code. Unable to crack this svg
@skotz

skotz · 2021-05-11T17:20:50Z

This library wasn't really built for SVGs so you might have to build something custom. The SVG format is absolutely the least secure CPTCHA format because it just hands you the outline of every object. What I would do is actually try just string parsing the path data out of the SVG markup and seeing if you find patterns. Like maybe all "A" characters have the exact same path data. It's quite possible you could get 100% accuracy with that method.

sagar-desshmukh · 2021-05-11T22:36:32Z

Nope unable to find any pattern.
Would you like to give this a shot?
@skotz

skotz · 2021-05-11T23:16:21Z

Unfortunately I don't have the time right now.

My suggestion is that you extract each <path> from the image and convert them to arrays of points (try googling something like "javascript svg to points"), toss all but the 5 paths with the most points (which should represent the 5 characters in the CAPTCHA), and then compare similar paths using a contour analysis library. That should result in almost 100% accuracy.

This library doesn't currently support SVG; however, another (less effective option) might be to first get an SVG to PNG library to convert it so this library can be used. If possible, remove the lines before converting. SVGs have way more information than PNGs, so it's not the best option.

cp1797 added the question label May 11, 2021

skotz mentioned this issue May 11, 2021

Solve a simple SVG captcha #66

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Help solving SVG based captcha. #65

Help solving SVG based captcha. #65

cp1797 commented May 11, 2021

skotz commented May 11, 2021

skotz commented May 11, 2021

jimmylannister commented May 11, 2021

jimmylannister commented May 11, 2021

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skotz commented May 11, 2021

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skotz commented May 11, 2021

Help solving SVG based captcha. #65

Help solving SVG based captcha. #65

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cp1797 commented May 11, 2021

skotz commented May 11, 2021

skotz commented May 11, 2021

jimmylannister commented May 11, 2021

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