#VERSION,2.1
# $Id: nikto_user_enum_apache.plugin 152 2009-08-13 19:37:44Z deity $

###############################################################################
#  Copyright (C) 2004 CIRT, Inc.
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; version 2
#  of the License only.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
###############################################################################

###############################################################################
# PURPOSE
# Enumeration of users and directories in system (as Apache's ~username)
###############################################################################
# NOTES
# This plugin tries to enumerate all the users and directories
# in the system (of course the bruteforce attack is limited to a given range).
# In some Apache/UNIX systems this might give out many local users
# (which could later on be used for a ssh brute-force attack).
# This plugin was originally written by Javier Fernandez-Sanguino Pe–a
###############################################################################
sub nikto_user_enum_apache_init
{
   my $id =
   {
      name         => "user_enum_apache",
      full_name    => "Apache User Enumeration",
      author       => "Javier Fernandez-Sanguinoi Pena",
      description  => "Attempts to enumerate usernames by guessing usernames.",
      scan_method  => \&nikto_user_enum_apache,
      scan_cond    => '$CLI{mutate} =~ /3/ || $CLI{mutate} =~ /4/',
      copyright    => "2008 CIRT Inc."
   };
   return $id;
}

sub nikto_user_enum_apache
{
   my ($mark) = @_;
   my $url;
   my @cgiwraps, @cfgcgi=split(/ /, $VARIABLES{"\@CGIDIRS"});
   
   # Set the URL according to the mutate version
   my @mutates=split(//,$CLI{mutate});
   foreach my $option (@mutates)
   {
      if ($option eq "3")
      {
         $url="/~";
         # First check whether we use a dictionary attack of brute force it
         if (defined $CLI{mutate-options})
         {
            # We have options - assume it is a dictionary attack
            nikto_user_enum_apache_dictionary($url);
         }
         else
         {
            nikto_user_enum_apache_brute($url);
         }
      }
      if ($option eq "4")
      {
         # Check for existence of cgiwrap
         foreach my $cgidir (@CFGCGI)
         {
            my $curl = "$cgidir" . "cgiwrap";
            (my $result, $content) = nfetch($mark,"$curl", "GET");
            if ($content =~ /check your URL/i)
            {
               push(@cgiwraps, "$curl");
               $valid++;
            }
         }
         
         foreach my $cgiwrap (@cgiwraps)
         {
            $url="$cgiwrap/~";
            # First check whether we use a dictionary attack of brute force it
            if (defined $CLI{mutate-options})
            {
               # We have options - assume it is a dictionary attack
               nikto_user_enum_apache_dictionary($url);
            }
            else
            {
               nikto_user_enum_apache_brute($url);
            }
         }
      }
   }
}

sub nikto_user_enum_apache_brute
{
   nprint("- Enumerating Apache users (1 to 5 characters).", "v");

   # Note1: This script only generates names with letters A-Z (no numbers)
   #
   # Note2: this script will generate SUM(26^n)(n=$min to $max)
   # it's probably faster to write this to a file than to generate it
   # on the fly BTW.
   #
   # Of course, it could be optimized to skip some "strange"
   # combinations of usernames, but hey, then it wouldn't
   # be 'brute force' would it? (jfs)

   my $text = "a";
   my $ctr  = 0;
   my $message="Valid users found via Apache enumeration: ";
   my $result, $content;
   my @foundusers=();
   while (length($text) <= 5)
   {
      if (($ctr % 500) eq 0) { nprint("- User enumeration guess $ctr ($text)", "v"); }
      (my $result, $content) = nfetch($mark,"/~" . $text, "HEAD");
      my $user = nikto_user_enum_apache_check($result, $text);
      if (defined $user)
      {
         push(@foundusers,$user);
      }
      $text++;
      $ctr++;
   }
   if ($found)
   {
      add_vulnerability($mark, $message . join(' ',@foundusers), 999997, "637", "HEAD", "/");
   }
   
}

sub nikto_user_enum_apache_dictionary
{
   my $filename=$CLI{mutate-options};
   my $message="Valid users found via Apache enumeration: ";
   my @foundusers=();
   my $result, $content;
   my $ctr=0;
   
   nprint("- Enumerating Apache users (using dictionary $filename).", "v");
   unless (open(IN, "<$filename"))
   {
      nprint("- ERROR: Unable to open dictionary file $filename: $!.");
   }

   # Now attempt on each entry
   while (<IN>)
   {
      chomp;
      s/\#.*$//;
      # remove preceding ~ just in case
      s/^~//;
      if ($_ eq "" ) { next };
      if (($ctr % 500) == 0) { nprint("- User enumeration guess $ctr ($_)", "v"); }
      (my $result, $content) = nfetch($mark,"/~" . $_, "HEAD");
      my $user = nikto_user_enum_apache_check($result, $_);
      if ($user)
      {
         push(@foundusers,$user);
      }
      $ctr++;
   }
   close(IN);
   if (scalar(@foundusers))
   {
      add_vulnerability($mark, $message . join(' ',@foundusers), 999997, "637", "HEAD", "/");
   }
}

sub nikto_user_enum_apache_check
{
   (my $code, $user) = @_;
   my $result="";
   
   foreach my $found (split(/ /, $VARIABLES{"\@HTTPFOUND"}))
   {
      if ($code eq $found)
      {
         $result=$user;
         last;
      }
   }
   
   return $result;
}     

1;