Making a fiddler script to replace a number with a random number

[maca G]

Hi everyone.

I need to make a script to replace a number present on a request with a random number.

Im new to fiddler and i dont really know where should i start, I already installed fiddlescript editor but i cant find a sample script so im kinda lost :/.

All i could find about this was this post https://groups.google.com/forum/#!topic/httpfiddler/zmbdm40483s

So i added import Microsoft.JScript at the top of the script but i dont know what should i do next.

Any help will be appreciated.

Thanks in advance.

[maca G]

I cant edit the original post but heres an update:

I didnt know i could just edit the original customrules.js

Now that i know that i just need to know how to replace a number on a request with a random generated one  using MathObject.random()}

The request looks like this:

00000100000010000:1234567890:1:3:WindowsNoEditor:1:7:0:0

I just need to replace the numbers that are in between ":" (in this case, 1234567890).

Btw do i need to download anything else to achieve this?

[EricLaw]

You don't need to download anything else.

What does the full request look like? Is the target text in the body? Is the request always to the same server or url?

[maca G]

Thanks for the reply.

The entire request would be: http://pastebin.com/ACC4ZgL3

The target text is in the body, and yes it is the same server, however the url changes a bit everytime i login for example: www.example.com/myuseridnumberhere/requestIwantToEditHere

My user id number changes everytime i login.

[EricLaw]

So you'd do something like this inside OnBeforeRequest:

  if (oSession.HostnameIs("api.prod.capcomfighters.net") && 

     oSession.HTTPMethodIs("POST"))

  {

       oSession.utilReplaceInRequest("form-data; name=\"game_rpt\"\n\n",

                                                          "form-data; name=\"game_rpt\"\n\n"+oSession.id);

       oSession["ui-backcolor"] = "red";

  }

You should try that first and see whether it's modifying the request in the right place. If the server is picky about the length of the number our script can get more complex...

[maca G]

Thanks Eric, I got it working with this one

        if (oSession.uriContains("match")){

            oSession.utilReplaceInRequest("1234567890", MathObject.random());

One more question, if I want to replace just two numbers (the server is picky about the amount of numbers in another part of the request) what should i do?

Thanks.

[maca G]

I will explain a little bit more. For example, i want to do this:

1. ----PostData
2. Content-Disposition: form-data; name="player_rpt"
3.  
4. 4090921472:21:3126787584:XX::::::::::::

I want to replace XX with two random numbers.

[maca G]

Ok, im using Math.floor(Math.random() * 98); and it works fine! It generates a random number between 0 and 97
Last question: is there any way to make it pick a number between 30 and 97 instead?
Thanks!

[EricLaw]

30 + Math.floor(Math.random() * 68);