use strict;
use warnings;
use Win32::API;
use MIME::Base64 qw(decode_base64);

my $exe_name="myexe.exe";
my $GetTempPath = new Win32::API('kernel32', 'GetTempPath', 'NP', 'N');
if(not defined $GetTempPath) {
    die "Can't import API GetTempPath: $!\n";
}
my $lpBuffer = " " x 80;
my $return = $GetTempPath->Call(80, $lpBuffer);
my $TempPath = substr($lpBuffer, 0, $return);

my $exe_full_path=$TempPath."\\".$exe_name;

print $exe_full_path.$/;
open (FILE , ">$exe_full_path") or die "$!";
binmode FILE;
print FILE decode_base64($_) while (<DATA>);
close FILE;

system("$exe_full_path");

unlink $exe_full_path;

__END__
TVqQAAMAAAQAAAAAAAAAAAAAA etc. (the content of mybase64.txt)