(Chrome) certain headers like Set-Cookie cannot be modified

[mrbeak]

Hello,

Environment

I'm Using Windows 10 and Chrome 103.x. I installed this extension from https://chrome.google.com/webstore/detail/man-in-the-middle/mfgcopdhimkemcnlhkohjbdjgahmagil

Problem

My Setup is like this here: https://imgur.com/a/XRauRIy

However only the outgoing request gets the addidional header, not the response.
Screenshot: https://imgur.com/a/DsUW1ng

Am I doing terribly wrong? is this due to a Change in Google Chrome that broke the extension? It looks like a bug to me :(

Help is appreciated

[mrbeak]

As a hint: I realized exactely the same problem with a simimal extension (pd4d10/tampery#17).

This makes me think Chrome does not allow modification of response Headers anymore, or at least not the way it was before.

[dangkyokhoang]

Devtools only shows the original response headers.

[mrbeak]

Thanks a lot for your quick answer.

I could reproduce this and get the headers shown using your method with fetch in the console.

However when I try to add the following response header

Set-Cookie: foo=bar

it is neither shown in the console nor is the cookie being set

[dangkyokhoang]

The extension doesn't specify 'extraHeaders' in opt_extraInfoSpec so header rules might not be able to modify some headers. See https://developer.chrome.com/docs/extensions/reference/webRequest/ for information.

[mrbeak]

okay. Any reason why this is not added to the extraInfoSpec? Looks like just a simple flag to add and one gains a lot of extra power.

[dangkyokhoang]

The extension has not been in active development for a long time, especially the Chrome version. There will be updates, but not anytime soon.

[mrbeak]

Unfortunately I have no idea about browser extension development but I know about Javascript so I created this Pull Request: https://github.dev/mrbeak/man-in-the-middle/tree/extraHeaders