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88d9af2c SS |
1 | package Guardian::Parser; |
2 | use strict; | |
3 | use warnings; | |
4 | ||
5 | use Exporter qw(import); | |
6 | ||
cfe5a220 | 7 | our @EXPORT_OK = qw(IsSupportedParser Parser); |
88d9af2c | 8 | |
cfe5a220 SS |
9 | # This hash contains all supported parsers and which function |
10 | # has to be called to parse messages in the right way. | |
88d9af2c | 11 | my %logfile_parsers = ( |
cfe5a220 | 12 | "snort" => \&message_parser_snort, |
88d9af2c SS |
13 | ); |
14 | ||
15 | # | |
16 | ## The main parsing function. | |
17 | # | |
18 | ## It is used to determine which sub-parser has to be used to | |
19 | ## parse the given message in the right way and to return if | |
20 | ## any action should be performed. | |
21 | # | |
22 | sub Parser ($$) { | |
cfe5a220 | 23 | my ($parser, @message) = @_; |
88d9af2c SS |
24 | |
25 | # If no responsible message parser could be found, just return nothing. | |
cfe5a220 | 26 | unless (exists($logfile_parsers{$parser})) { |
88d9af2c SS |
27 | return; |
28 | } | |
29 | ||
cfe5a220 SS |
30 | # Call responsible message parser. |
31 | my $action = $logfile_parsers{$parser}->(@message); | |
88d9af2c | 32 | |
dd048373 SS |
33 | # If the parser successfully parsed the message, an action |
34 | # has been returned. | |
35 | if ($action) { | |
36 | # Return which action should be performed. | |
37 | return "count $action"; | |
38 | } | |
39 | ||
40 | # If the parser was not able to parse the the given message | |
41 | # in the right way, return Nothing. | |
42 | return; | |
88d9af2c SS |
43 | } |
44 | ||
cfe5a220 SS |
45 | # |
46 | ## IsSupportedParser function. | |
47 | # | |
48 | ## This very tiny function checks if a given parser name is available and | |
49 | ## therefore a supported parser. | |
50 | # | |
51 | ## To perform these check, the function is going to lookup if a key in the | |
52 | ## hash of supported parsers is available | |
53 | # | |
54 | sub IsSupportedParser ($) { | |
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 | ||
88d9af2c SS |
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 | # | |
53a02397 SS |
74 | ## XXX Currently the parser only supports IPv4. Add support for IPv6 at a |
75 | ## later time. | |
76 | # | |
77 | sub message_parser_snort(@) { | |
88d9af2c SS |
78 | my @message = @_; |
79 | ||
53a02397 SS |
80 | # The name of the parser module. |
81 | my $name = "SNORT"; | |
82 | ||
83 | # Variable to store the grabbed IP-address. | |
84 | my $address; | |
85 | ||
86 | # Default returned message in case no one could be grabbed | |
87 | # from the snort alert. | |
88 | my $message = "An active snort rule has matched and gained an alert."; | |
89 | ||
90 | # A snort alert contains multiple lines, loop through all lines | |
91 | # to parse the complete alert. | |
92 | foreach my $line (@message) { | |
93 | # Check Priority Level and skip the alert if it is to low. | |
94 | #if ($line =~ /.*\[Priority: (\d+)\].*/) { | |
95 | # return unless($1 < $priority); | |
96 | #} | |
97 | ||
98 | # Search for a line like xxx.xxx.xxx.xxx -> xxx.xxx.xxx.xxx | |
99 | if ($line =~ /(\d+\.\d+\.\d+\.\d+)+ -\> (\d+\.\d+\.\d+\.\d+)+/) { | |
100 | # Store the grabbed IP-address. | |
101 | $address = $1; | |
102 | } | |
103 | ||
104 | # Search for a line like xxx.xxx.xxx.xxx:xxx -> xxx.xxx.xxx.xxx:xxx | |
105 | elsif ($line =~ /(\d+\.\d+\.\d+\.\d+):\d+ -\> (\d+\.\d+\.\d+\.\d+):\d+/) { | |
106 | # Store the obtained IP-address. | |
107 | $address = $1; | |
108 | } | |
109 | ||
110 | # Obtain the reported reason. | |
111 | if ($line =~ /.*msg:\"(.*)\".*/) { | |
112 | # Store the extracted message. | |
113 | $message = $1; | |
114 | } | |
115 | } | |
116 | ||
117 | # Check if at least the IP-address information are obtained from the | |
118 | # provided alert. | |
119 | if ($address) { | |
120 | # Return the extracted values. | |
121 | return "$address $name $message"; | |
122 | } | |
123 | ||
124 | # If we got here, the alert could not be parsed correctly, return nothing. | |
125 | return; | |
88d9af2c SS |
126 | } |
127 | ||
128 | 1; |