This indicates an attack attempt to exploit a Backdoor vulnerability in vsftpd v2.3.4.
This backdoor was introduced into the vsftpd-2.3.4.tar.gz archive between June 30th 2011 and July 1st 2011 according to the most recent information available. This backdoor was removed on July 3rd 2011.It allows remote attacks to execute arbitrary PHP code on the system by sending a connection request on TCP port 6200.
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the website: