Re: open file using variable passed by form

The cgi script folder is normally not writeable to by the web server for security. Try adding

use CGI::Carp 'fatalsToBrowser'; # use only while debugging
[download]

to your script to see what is causing the internal error

or try this SSCCE which writes to /tmp

#!/usr/bin/perl
use strict;
use warnings;
use CGI qw/:standard/;
use CGI::Carp 'fatalsToBrowser'; # use only while debugging
use Cwd;

my $cwd = getcwd(); # current working directory

my $event      = param('event') || 1;
my $newCOMMENT = param('newCOMMENT') || 'test comment';
my $commentUID = time();
my $path       = '/tmp';
my $fileA      = "$path/$event.txt";
my $fileB      = "$path/$commentUID.txt";

if ($newCOMMENT ne "") {
  open AFH, '>>', $fileA 
    or die "Could not open $fileA : $!";
  print AFH "$commentUID\n";
  close AFH;
    
  open BFH, '>>', $fileB 
    or die "Could not open $fileB : $!";
  print BFH "$newCOMMENT\n";
  close BFH ;
}

print header,start_html;
print pre("
cwd        : $cwd
event      : [$event]
newCOMMENT : [$newCOMMENT]
commentUID : $commentUID");
print end_html;
[download]

poj

Comment on Re: open file using variable passed by form Select or Download Code

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Re^2: open file using variable passed by form by haukex (Archbishop) on Mar 17, 2018 at 10:04 UTC
Note to the OP: this version still suffers from several of the same issues I describe here. I also think removing taint mode switch `-T` makes it less safe. Updated wording.	[reply] [d/l]
Re^3: open file using variable passed by form by poj (Abbot) on Mar 17, 2018 at 10:26 UTC
Yes I agree, this example was just to check write permissions. I removed -T so it would run on IIS. poj	[reply]
Re^2: open file using variable passed by form by michael.kitchen (Novice) on Mar 19, 2018 at 05:01 UTC
Thank you so much for taking time to help. It seems that -T was killing my script and used to code from haukex. Used (and learned from) some of your code too. I have a working script (at this point in time). You may see it again for another reason. :) For some reason I could not open a file (for writing) in /tmp, but was able to in a new sub-directory of cgi-bin...go figure. Again, thanks!!!	[reply]
Re^3: open file using variable passed by form by haukex (Archbishop) on Mar 19, 2018 at 08:27 UTC
For some reason I could not open a file (for writing) in /tmp, but was able to in a new sub-directory of cgi-bin...go figure. That's strange, and could be an indication that your script is running with privileges that are higher than e.g. the `nobody` user that webservers commonly use to run scripts. That'd be another reason to be incredibly careful with using form input for filenames and potentially other things. Attackers would happily exploit a security hole that allows them to create files to, for example, set up phishing sites under your domain. Taint mode is a good idea in this case because it forces you to think about certain cases. But it's of course also not a silver bullet - thinking about what you are doing with user input is always a good idea :-)	[reply] [d/l]


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