use warnings;
use strict;

while (<DATA>) {
chomp;
s/
  (logger\s+)
  ("[^"]*"|\w+)(,)([^,]+)(.*)
/$1 . ("X" x length($2)) . $3 . ("X" x length($4) . $5)/ex;
print "$_\n";
}

__DATA__
logger abcdef123,"$£*&GHi^
logger "765)(?>jh",hhhhhh,joebloggs
logger "7,)(?>jh",yyyyyyy,fredbloggs

##</code><code>##

logger XXXXXXXXX,XXXXXXXXX
logger XXXXXXXXXXX,XXXXXX,joebloggs
logger XXXXXXXXXX,XXXXXXX,fredbloggs