The Black Art of PHP

Some very interesting information on php exploits. Make sure your site is not at risk. Learn the tricks of a php Hacker

while this ebook is short it has some interesting information on exploits of php. Perhaps more importantly just how to do it with coded example ;).

download Link
http://www.oxyshare.com/get/142469626449206e1b1d5c7.30537509/the_black_art_of_php.pdf.html