1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
-- Gemeinschaft 5 module: perimeter class
-- (c) AMOOMA GmbH 2013
--
module(...,package.seeall)
Perimeter = {}
function Perimeter.new(self, arg)
arg = arg or {}
object = arg.object or {}
setmetatable(object, self);
self.__index = self;
self.log = arg.log;
self.class = 'perimeter'
self.database = arg.database;
self.domain = arg.domain;
self.sources = {};
self.checks_available = {
check_frequency = self.check_frequency,
check_username_scan = self.check_username_scan,
check_bad_headers = self.check_bad_headers,
};
return object;
end
function Perimeter.setup(self, event)
require 'common.configuration_table';
local config = common.configuration_table.get(self.database, 'perimeter');
self.contact_count_threshold = 10;
self.contact_span_threshold = 2;
self.name_changes_threshold = 2;
self.blacklist_file = '/var/opt/gemeinschaft/firewall/blacklist';
self.blacklist_file_comment = '# PERIMETER_BAN - points: {points}, generated: {date}';
self.blacklist_file_entry = '{received_ip} udp 5060';
self.ban_command = 'sudo /sbin/service shorewall refresh';
self.ban_threshold = 20;
self.ban_tries = 1;
if config and config.general then
for key, value in pairs(config.general) do
self[key] = value;
end
end
self.checks = config.checks;
self.bad_headers = config.bad_headers;
self.log:info('[perimeter] PERIMETER - setup perimeter defense');
end
function Perimeter.record_load(self, event)
if not self.sources[event.key] then
self.sources[event.key] = {
contact_first = event.timestamp,
contact_last = event.timestamp,
contact_count = 0,
span_contact_count = 0,
span_start = event.timestamp,
points = 0,
banned = 0,
}
end
return self.sources[event.key];
end
function Perimeter.format_date(self, value)
local epoch = tonumber(tostring(value/1000000):match('^(%d-)%.'));
return os.date('%Y-%m-%d %X', tonumber(epoch)) .. '.' .. (value-(epoch*1000000));
end
function Perimeter.record_update(self, event)
event.record.contact_last = event.timestamp;
event.record.contact_count = event.record.contact_count + 1;
event.record.points = event.points or event.record.points;
event.record.span_start = event.span_start or event.record.span_start;
event.record.span_contact_count = (event.span_contact_count or event.record.span_contact_count) + 1;
event.record.users = event.users or event.record.users;
end
function Perimeter.check(self, event)
event.record = self:record_load(event);
-- self.log:debug('[', event.sequence, '] PERIMETER_CHECK - received: ', event.received_ip, ':', event.received_port, ', contacts: ', event.record.contact_count, ', since: ', self:format_date(event.record.contact_first), ', points: ', event.record.points);
if event.record.banned <= self.ban_tries then
for check_name, check_points in pairs(self.checks) do
if self.checks_available[check_name] then
local result = self.checks_available[check_name](self, event);
if tonumber(result) then
event.points = (event.points or event.record.points) + result * check_points;
end
end
end
end
if (event.points or event.record.points) > self.ban_threshold and event.record.banned <= self.ban_tries then
if event.record.banned > 0 and event.record.banned == self.ban_tries then
self.log:warning('[', event.sequence, '] PERIMETER_BAN_FUTILE - points: ', event.points,', event: ', event.class, ', ip: ', event.received_ip, ', to: ', event.to_user, '@', event.to_host);
else
self.log:notice('[', event.sequence, '] PERIMETER_BAN - threshold reached: ', event.points,', event: ', event.class, ', ip: ', event.received_ip, ', to: ', event.to_user, '@', event.to_host);
if event.record.banned == 0 then
self:append_blacklist_file(event);
end
self:execute_ban(event);
end
event.record.banned = event.record.banned + 1;
event.span_start = event.timestamp;
event.span_contact_count = 0;
event.points = 0;
end
self:record_update(event);
end
function Perimeter.check_frequency(self, event)
if event.record.span_contact_count >= self.contact_count_threshold then
self.log:info('[', event.sequence, '] PERIMETER_FREQUENCY_CHECK - contacts: ', event.record.span_contact_count, ' in < ', (event.timestamp - event.record.span_start)/1000000, ' sec, threshold: ', self.contact_count_threshold, ' in ', self.contact_span_threshold, ' sec');
event.span_contact_count = 0;
event.span_start = event.timestamp;
return 1;
elseif (event.timestamp - event.record.span_start) > (self.contact_span_threshold * 1000000) then
event.span_contact_count = 0;
event.span_start = event.timestamp;
end
end
function Perimeter.check_username_scan(self, event)
if not event.to_user then
return;
end
if not event.record.users then
event.users = { event.to_user };
return;
end
if #event.record.users >= self.name_changes_threshold then
self.log:info('[', event.sequence, '] PERIMETER_USER_SCAN - user names: ', #event.record.users, ', threshold: ', self.name_changes_threshold);
event.users = {};
return 1;
else
for index=1, #event.record.users do
if event.record.users[index] == tostring(event.to_user) then
return
end
end
if not event.users then
event.users = event.record.users or {};
end
table.insert(event.users, tostring(event.to_user));
end
end
function Perimeter.check_bad_headers(self, event)
local points = nil;
for name, pattern in pairs(self.bad_headers) do
local success, result = pcall(string.find, event[name], pattern);
if success and result then
self.log:info('[', event.sequence, '] PERIMETER_BAD_HEADERS - ', name, '=', event[name], ' ~= ', pattern);
points = (points or 0) + 1;
end
end
return points;
end
function Perimeter.append_blacklist_file(self, event)
local blacklist = io.open(self.blacklist_file, 'a');
if not blacklist then
self.log:error('[', event.sequence, '] PERIMETER_APPEND_BLACKLIST - could not open file: ', self.blacklist_file);
return false;
end
event.date = self:format_date(event.timestamp);
if self.blacklist_file_comment then
blacklist:write(self:expand_variables(self.blacklist_file_comment, event), '\n');
end
self.log:debug('[', event.sequence, '] PERIMETER_APPEND_BLACKLIST - ip: ', event.received_ip);
blacklist:write(self:expand_variables(self.blacklist_file_entry, event), '\n');
blacklist:close();
end
function Perimeter.execute_ban(self, event)
local command = self:expand_variables(self.ban_command, event);
self.log:debug('[', event.sequence, '] PERIMETER_EXECUTE_BAN - ip: ', event.received_ip, ', command: ', command);
local result = os.execute(command);
end
function Perimeter.expand_variables(self, line, variables)
return (line:gsub('{([%a%d%._]+)}', function(captured)
return variables[captured] or '';
end))
end
|
