FiddlerClassic Websocket binary to text

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Fiddler Classic
clement
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clement asked on 08 May 2022, 03:09 PM

Hi everyone,

After hours of using the Progress Telerik Fiddler Classic, i'm blocked. I'm trying to intercept a web socket secure (WSS) over TLS, that's why I'm using the HTTPS MITM Proxy.

I have registred all the SSL Root certificates and everything is working. But when I show the Web socket inspector, I couldn't translate the binary to human readable text. After some researchs, it seems that I need to decode the payload ?

Does FiddlerClassic permit to translate the binary of a web socket frame to the text human readable ?

Here a screenshot:

 

Big thanks in advance for all your help. Have a nice end of day,

Respectfully

MK
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commented on 18 Jun 2023, 02:58 AM | edited

Hi Clement,

Currently, I'm doing the same thing, I'm trying to decode the binary messages that are being sent and received to/from the server.

I checked Nick Iliev answer, but unfortunately the URL isn't working anymore.

Have you succeeded in decoding those messages?

**Edit**: I'm trying to do this 4 days ago, and still stuck here.
Nick Iliev
Telerik team
commented on 20 Jun 2023, 05:37 AM

Hey Clement,

 

The WebSocket messages don't have to be in human-readable form, and some developers are adding a layer of encryption to prevent decryption. That technique is often observed in chat implementations. If you could, post a link with the WS connection you are capturing so we can look at the case and test it on our side.

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Nick Iliev
Telerik team
answered on 10 May 2022, 06:28 AM

Hello Clement,

 

There are third-party tools that could be used for decoding binary WS messages but you might also want to check these instructions as well https://quick-adviser.com/how-do-you-decode-a-binary-websocket/#How_do_I_decode_Websocket_messages

As a side note, not sure why you are going through MITM proxy as both Fiddler Classic and Fiddler Everywhere are supporting WebSocket traffic out-of-the-box.

 

Regards,
Nick Iliev
Progress Telerik

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clement
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commented on 10 May 2022, 08:49 AM

Hello Nick,

 

Thanks for your time and your help. Yes it's true, MITM proxy works, and Fiddler classic even better and easier. I have tried both in order to see if one of them have a third-party tools to deocde binary WS messages.

You talk about those tools, do you have a name ? this problem is slowing me for days and I already saw your link about quick-adviser, I'm really not the best programmer and I have lacks of knowledge about binary. It would be very useful to have one of the third-party tools you mentionned.

 

Have a nice week

Respectfully

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Nick Iliev
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