To disable it, set this preference
```
sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.captive.control Active -boolean false
```
In case, you would ever want to remove this setting, you can do:
```
sudo defaults delete /Library/Preferences/SystemConfiguration/com.apple.captive.control Active
```
Then, as @Leon mentions, use the regular web browser to login. Or if you are on a network where that somehow does not work then you can still try and open the app manually ( located at /System/Library/CoreServices/Captive Network Assistant.app )