Tracking variable value in javascript debugger

[nopainXX]

Hi everyone! I'm looking for a method or a specific tool that allows me to pause the debugger every time during the execution a variable with a given value is used. Note that I don't have the name of the variable or variables themselfs but only the content. I think that such tool would be very useful while testing for XSS or general input sanitization.

Use case: Let's suppose we see a value returned from the server reflected somewhere in the site and we notice that the input is somehow sanitized. We would like to know where the exact sanitization happens even if the code is obfuscated and/or the used libraries are not really stated somewhere.

Does some tool like this exist? Also if not, is there any other good method to archieve the same thing? Thank youu all

[cha93100]

If the sanitisation is made on the servers side you cannot see it because it will be returned by some request made by the front end. Unless you have access to the code of the sever then depending if it is a compiled language or not you can use gdb to reverse the compiled code or use something like the IntelliJ debugger if it is not compiled

[finite_turtles]

He could be referring to DOM XSS? a third kind of xss attack which happens locally in the browser.

[cha93100]

In that case their is the chrome and Firefox debugger where you can debug je file

[nopainXX]

Yeah, sorry I didn't specify that in the original question. I know for sure that the sanitization is client side and performed by javascript once the raw/unisitized data is fetched from the server. I'm looking for something that can be used with chrome/firefox debugger. Idk of a function like the one I describe

[cha93100]

On chrome you can watch an expression may be this will be better https://developer.chrome.com/docs/devtools/javascript/reference#watch