Derive a dynamically generated value from js code

Question

On the above page, the raw HTML page contains something like the following.

<input type="hidden" name="g-recaptcha-response-data[login]" id="g-recaptcha-response-data-login" data-sitekey="6LfHWdoUAAAAAMAqpubAaMDSNO20QDM8sbxb05Hf" class="g-recaptcha g-recaptcha-response "/>

But the rendered page in a browser has been modified so that this entry looks like the following.

<input type="hidden" name="g-recaptcha-response-data[login]" id="g-recaptcha-response-data-login" data-sitekey="6LfHWdoUAAAAAMAqpubAaMDSNO20QDM8sbxb05Hf" class="g-recaptcha g-recaptcha-response " style="" value="03AGdBq25SYaNBBVkcm8vcY1VFDLhiqgwcBrN1yk_5dkBgo6_fVV9Ng_K-3NNrn-ynwyUoGE0gYpFE1kVzApQLN9aCL73GzxIznBRki1MiooW6Hek4i1uJ-TL9i6QZRwvCRbRgeVySpYmM32chx6xPutEJyaZ2PCpFGGbkwpg_G7WBH5zk9MJ93hNnQv6hfYbEF3qnzs8NVY4BHmotYjR3LtrLeM9mJkt1w3cM-Kp-Dz0h0QKTrW48QjEByusHkHS1cfLCN7Zzr67UHuRhm_xRlQ3BI1QvWynShfrBKH_cARrODSyaFJ0e-WDdOVY5GdkPiUCOSgm8BP38KbFvxWt08hw5S4YjpPLren7ugfoJCDOBF6jmjiauEoOyIV5TcOrqa42xzuVGKDoY9c-J_wwO15EYHc3yV4ux_LQFkNO-NLP2Dr2CtWONW5CkgG2gTkoYr4O8qz_T2AaC">

I can not find out how the value is calculated using the js code on the webpage. Could anybody show me how derive the value manually?

score 0 · Answer 1 · answered Nov 21 '21 at 20:10

0

Seems like the token is generated and set here:

grecaptcha.execute('6LfHWdoUAAAAAMAqpubAaMDSNO20QDM8sbxb05Hf', {action: 'login'}).then(function(token) {
                setInputWithRecaptchaResponseTokenForLogin('g-recaptcha-response-data-login', token)
              });

grecaptcha.execute is defined in recaptcha__en.js which is heavily obfuscated, so I cannot help you any further.

answered Nov 21 '21 at 20:10

deterjan

348
3
16

Is there a way to run the is code without being in a browser? – user1424739 Nov 21 '21 at 20:34
How do you know it is not in https://www.recaptcha.net/recaptcha/api.js?render=6LfHWdoUAAAAAMAqpubAaMDSNO20QDM8sbxb05Hf? – user1424739 Nov 21 '21 at 23:07

Derive a dynamically generated value from js code

1 Answers1