https://medium.com/@cedriczirtacic/ejecutando-opcodes-desde-memoria-9700e5a7e02

opcodes.pl

#!/usr/bin/perl -w

use strict;
use warnings;

my $bin = $ARGV[0];
my $func= $ARGV[1];
die("./$0 <binary> <function>") if (!defined $bin or !defined $func);

my @shellcode;
open(H,"objdump -D $bin |");
while(<H>){
    if(/<$func>:/){
        while(<H>){
            last if(/^\n*$/);
            my($ops) = $_ =~ m/[0-9a-f]+:[\s]+?((?:[^\s]{2}\s)+)+\s+/g;
            if ($ops){
                foreach ($ops =~ m/(?:([a-z0-9]+)\s)/g) {
                    push @shellcode, $_
                }
            }
        }
        last;
    }
}
close(H);

printf "\tsubq \$%d, %%rsp\n", ($#shellcode+1);
print "shellcode:\n\t";
for( my $i = $#shellcode, my $j=1; $i >= 0; $i--,$j++ ) {
    printf "movb \$0x%2s, -%d(%%rbp)\n\t", $shellcode[$i], $j;
}

print $/ and exit(0);
__END__