Some suspicious software making request to nmcheck.gnome.org

In the last few days my system has started popping up an Ubuntu default web-browser and making a request to nmcheck.gnome.org website and immediately shutting off.

Since this happened I cannot run system updates.

Also, I am a php developer and I cannot run composer install or composer update

How can I find this script and delete it forever?

Thank you

nmcheck.gnome.org is not malware. It is the gnome network manager connectivity check (for captive portals/hotspots). Click the link and you will see a single text file with a text in it. It should be "NetworkManager is online".

Check /etc/NetworkManager/NetworkManager.conf. There probably is a section with this in it:

[Connectivity] 
uri=http://nmcheck.gnome.org/check_network_status.txt

on Ubuntu 20.04 no [Connectivity] line like accepted answer in /etc/NetworkManager/NetworkManager.conf.

But you can disable the auto connectivity check by:

1. Go to Settings app
2. Go to Privacy menu
3. On Connectivity tab, uncheck Connectivity Checking