It might be a virus or a bot...
According to top:
Tasks: 525 total, 1 running, 384 sleeping, 0 stopped, 140 zombie
# ps -ef|fgrep perl
www-data 3759 32191 0 21:37 ? 00:00:00 [perl] <defunct>
www-data 10877 32191 0 21:40 ? 00:00:00 [perl] <defunct>
www-data 20877...