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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, |
0b1fe046 | 13 | "ssh" => \&message_parser_ssh, |
88d9af2c SS |
14 | ); |
15 | ||
16 | # | |
17 | ## The main parsing function. | |
18 | # | |
19 | ## It is used to determine which sub-parser has to be used to | |
20 | ## parse the given message in the right way and to return if | |
21 | ## any action should be performed. | |
22 | # | |
23 | sub Parser ($$) { | |
cfe5a220 | 24 | my ($parser, @message) = @_; |
88d9af2c SS |
25 | |
26 | # If no responsible message parser could be found, just return nothing. | |
cfe5a220 | 27 | unless (exists($logfile_parsers{$parser})) { |
88d9af2c SS |
28 | return; |
29 | } | |
30 | ||
cfe5a220 SS |
31 | # Call responsible message parser. |
32 | my $action = $logfile_parsers{$parser}->(@message); | |
88d9af2c | 33 | |
72d0b626 SS |
34 | # Return which action should be performed. |
35 | return "count $action"; | |
88d9af2c SS |
36 | } |
37 | ||
cfe5a220 SS |
38 | # |
39 | ## IsSupportedParser function. | |
40 | # | |
41 | ## This very tiny function checks if a given parser name is available and | |
42 | ## therefore a supported parser. | |
43 | # | |
44 | ## To perform these check, the function is going to lookup if a key in the | |
45 | ## hash of supported parsers is available | |
46 | # | |
47 | sub IsSupportedParser ($) { | |
48 | my $parser = $_[0]; | |
49 | ||
50 | # Check if a key for the given parser exists in the hash of logfile_parsers. | |
51 | if(exists($logfile_parsers{$parser})) { | |
52 | # Found a valid parser, so return nothing. | |
53 | return 1; | |
54 | } | |
55 | ||
56 | # Return "False" if we got here, and therefore no parser | |
57 | # is available. | |
58 | return; | |
59 | } | |
60 | ||
88d9af2c SS |
61 | # |
62 | ## The Snort message parser. | |
63 | # | |
64 | ## This subfunction is responsible for parsing sort alerts and determine if | |
65 | ## an action should be performed. | |
66 | # | |
67 | sub message_parser_snort($) { | |
68 | my @message = @_; | |
69 | ||
70 | # XXX | |
71 | # Currently this parser just returns a simple message. | |
ebd440a9 | 72 | return "$message[0] SNORT A simple Snort Message"; |
88d9af2c SS |
73 | } |
74 | ||
0b1fe046 SS |
75 | # |
76 | ## The SSH message parser. | |
77 | # | |
78 | ## This subfunction is used for parsing and detecting different attacks | |
79 | ## against the SSH service. | |
80 | # | |
81 | sub message_parser_ssh (@) { | |
82 | my @message = @_; | |
83 | ||
84 | # The name of the parser module. | |
85 | my $name = "SSH"; | |
86 | ||
87 | # Variable to store the grabbed IP-address. | |
88 | my $address; | |
89 | ||
90 | # Variable to store the parsed event. | |
91 | my $message; | |
92 | ||
93 | # Loop through all lines, in case multiple one have | |
94 | # been passed. | |
95 | foreach my $line (@message) { | |
96 | # Check for failed password attempts. | |
97 | if ($line =~/.*sshd.*Failed password for (.*) from (.*) port.*/) { | |
98 | # Store the grabbed IP-address. | |
99 | $address = $2; | |
100 | ||
101 | # Set event message. | |
102 | $message = "Possible SSH-Bruteforce Attack for user: $1."; | |
103 | } | |
104 | ||
105 | # This should catch Bruteforce Attacks with enabled preauth | |
106 | elsif ($line =~ /.*sshd.*Received disconnect from (.*):.*\[preauth\]/) { | |
107 | # Store obtained IP-address. | |
108 | $address = $1; | |
109 | ||
110 | # Set event message. | |
111 | $message = "Possible SSH-Bruteforce Attack - failed preauth."; | |
112 | } | |
113 | } | |
114 | ||
115 | # Check if at least the IP-address information has been extracted. | |
116 | if (defined ($address)) { | |
117 | # Return the extracted values and event message. | |
118 | return "$address $name $message"; | |
119 | } | |
120 | ||
121 | # If we got here, the provided message is not affected by any filter and | |
122 | # therefore can be skipped. Return nothing (False) in this case. | |
123 | return; | |
124 | } | |
125 | ||
88d9af2c | 126 | 1; |