sketchy nginx access log entries
Notice the magic string () { :; };. They are trying to poke around and see if your server is vulnerable to the ShellShock exploit. Perl is used here to print and see if the attack succeeded.
Test if your server is vulnerable to ShellShock. If it's not, you are clear.
See also: Is my server vulnerable to a perl exploit?
He's looking to do shellshock against you. The funny thing is that he misconfigured his attack. I do malware capture and his wget/fetch/etc fail because his package ain't there :-)