The only open-source Arabic ASR that is found up to now is “Arabisc” which was developed by Dr. Hussein Hiyassat et. al
Here is the download link: http://sourceforge.net/projects/arabisc/ (Gives an error at run-time)
But I’m still trying to contact the developer for a full access to the system to download if available.
Here is a full description of their work : http://www.springerlink.com/content/n3658k1758140266/