Setup the Fiddler certificate for Electron applications on Ubuntu

Environment

Fiddler Everywhere 1.0.0 and above
3rd-party application Any electron-based application
Operating System Ubuntu 18.0.4 and above

Description

Electron-based applications (like MSTeams) use Electron CA management, so the folder where the Fiddler Everywhere trust certificate must be installed is in ~/.pki/nssdb. To capture HTTPS traffic, you need to move the certificate to that folder and then use the certutil tool to install and trust it.

Solution

  1. Verify that your Ubuntu has the certutil tool. Install the tool through the following command:

    sudo apt install libnss3-tools
    
  2. Use the following command to install and trust the certificate:

    certutil -A -n "ROOT-CA" -t "TCu,Cu,Tu" -i /usr/share/ca-certificates/extra/FiddlerRootCertificate.crt -d sql:/home/${USER}/.pki/nssdb
    

    The above command assumes that you already have the root certificate installed at /usr/share/ca-certificates/extra. If that is not the case, install and trust as shown in the configuration article (so that you could capture HTTPS traffic from other applications and not only from electron applications).

  3. Restart Fiddler Everywhere and start capturing HTTPS traffic from MSTeams (or other electron-based applications).

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