Warning
You are looking at documentation for an older release. Not what you want? See the current release documentation.
The eXo Platform Favicon 
is packaged in platform-extension webapp: platform-extension.war!/favicon.ico.
You can override it by packaging it at the root of your extension,
for example custom-extension.war!/favicon.ico.
Note
Note that the icon should be 16x16 pixels to be well displayed.
For a quick test you can download an icon somewhere, like the Google favicon 
available at http://google.co.uk/favicon.ico.
Resize it to 16x16 and pack it in the extension.
After deploying your extension, you should remove images cache in the browser and refresh eXo Platform page. Here is the illustration with Google favicon replacing eXo Platform favicon:
