modules/Parser.pm

   1 package Guardian::Parser;
   2 use strict;
   3 use warnings;
   4
   5 use Exporter qw(import);
   6
   7 our @EXPORT_OK = qw(IsSupportedParser Parser);
   8
   9 # This hash contains all supported parsers and which function
  10 # has to be called to parse messages in the right way.
  11 my %logfile_parsers = (
  12         "httpd" => \&message_parser_httpd,
  13         "snort" => \&message_parser_snort,
  14         "ssh" => \&message_parser_ssh,
  15 );
  16
  17 #
  18 ## The main parsing function.
  19 #
  20 ## It is used to determine which sub-parser has to be used to
  21 ## parse the given message in the right way and to return if
  22 ## any action should be performed.
  23 #
  24 sub Parser ($$) {
  25         my ($parser, @message) = @_;
  26
  27         # If no responsible message parser could be found, just return nothing.
  28         unless (exists($logfile_parsers{$parser})) {
  29                 return;
  30         }
  31
  32         # Call responsible message parser.
  33         my $action = $logfile_parsers{$parser}->(@message);
  34
  35         # In case an action has been returned, return it too.
  36         if (defined($action)) {
  37                 # Return which action should be performed.
  38                 return "count $action";
  39         }
  40
  41         # Return undef, no action required.
  42         return undef;
  43 }
  44
  45 #
  46 ## IsSupportedParser function.
  47 #
  48 ## This very tiny function checks if a given parser name is available and
  49 ## therefore a supported parser.
  50 #
  51 ## To perform these check, the function is going to lookup if a key in the
  52 ## hash of supported parsers is available
  53 #
  54 sub IsSupportedParser ($) {
  55         my $parser = $_[0];
  56
  57         # Check if a key for the given parser exists in the hash of logfile_parsers.
  58         if(exists($logfile_parsers{$parser})) {
  59                 # Found a valid parser, so return nothing.
  60                 return 1;
  61         }
  62
  63         # Return "False" if we got here, and therefore no parser
  64         # is available.
  65         return;
  66 }
  67
  68 #
  69 ## The Snort message parser.
  70 #
  71 ## This subfunction is responsible for parsing sort alerts and determine if
  72 ## an action should be performed.
  73 #
  74 sub message_parser_snort($) {
  75         my @message = @_;
  76
  77         # XXX
  78         # Currently this parser just returns a simple message.
  79         return "$message[0] SNORT A simple Snort Message";
  80 }
  81
  82 #
  83 ## The SSH message parser.
  84 #
  85 ## This subfunction is used for parsing and detecting different attacks
  86 ## against the SSH service.
  87 #
  88 sub message_parser_ssh (@) {
  89         my @message = @_;
  90
  91         # The name of the parser module.
  92         my $name = "SSH";
  93
  94         # Variable to store the grabbed IP-address.
  95         my $address;
  96
  97         # Variable to store the parsed event.
  98         my $message;
  99
 100         # Loop through all lines, in case multiple one have
 101         # been passed.
 102         foreach my $line (@message) {
 103                 # Check for failed password attempts.
 104                 if ($line =~/.*sshd.*Failed password for (.*) from (.*) port.*/) {
 105                         # Store the grabbed IP-address.
 106                         $address = $2;
 107
 108                         # Set event message.
 109                         $message = "Possible SSH-Bruteforce Attack for user: $1.";
 110                 }
 111
 112                 # This should catch Bruteforce Attacks with enabled preauth
 113                 elsif ($line =~ /.*sshd.*Received disconnect from (.*):.*\[preauth\]/) {
 114                         # Store obtained IP-address.
 115                         $address = $1;
 116
 117                         # Set event message.
 118                         $message = "Possible SSH-Bruteforce Attack - failed preauth.";
 119                 }
 120         }
 121
 122         # Check if at least the IP-address information has been extracted.
 123         if (defined ($address)) {
 124                 # Return the extracted values and event message.
 125                 return "$address $name $message";
 126         }
 127
 128         # If we got here, the provided message is not affected by any filter and
 129         # therefore can be skipped. Return nothing (False) in this case.
 130         return;
 131 }
 132
 133 #
 134 ## The HTTPD message parser.
 135 #
 136 ## This subfunction is used for parsing and detecting different attacks
 137 ## against a running HTTPD service.
 138 #
 139 sub message_parser_httpd (@) {
 140         my @message = @_;
 141
 142         # The name of the parser module.
 143         my $name = "HTTPD";
 144
 145         # Variable to store the grabbed IP-address.
 146         my $address;
 147
 148         # Variable to store the parsed event.
 149         my $message;
 150
 151         # Loop through all lines, in case multiple one have
 152         # been passed.
 153         foreach my $line (@message) {
 154                 # This will catch brute-force attacks against htaccess logins (username).
 155                 if ($line =~ /.*\[error\] \[client (.*)\] user(.*) not found:.*/) {
 156                         # Store the grabbed IP-address.
 157                         $address = $1;
 158
 159                         # Set event message.
 160                         $message = "Possible WUI brute-force attack, wrong user: $2.";
 161                 }
 162
 163                 # Detect htaccess password brute-forcing against a username.
 164                 elsif ($line =~ /.*\[error\] \[client (.*)\] user(.*): authentication failure for.*/) {
 165                         # Store the extracted IP-address.
 166                         $address = $1;
 167
 168                         # Set event message.
 169                         $message = "Possible WUI brute-force attack, wrong password for user: $2.";
 170                 }
 171         }
 172
 173         # Check if at least the IP-address information has been extracted.
 174         if (defined ($address)) {
 175                 # Return the extracted values and event message.
 176                 return "$address $name $message";
 177         }
 178
 179         # If we got here, the provided message is not affected by any filter and
 180         # therefore can be skipped. Return nothing (False) in this case.
 181         return;
 182 }
 183
 184 1;