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
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
|
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements. See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to you under the Apache License, Version 2.0
-- (the "License"); you may not use this file except in compliance with
-- the License. You may obtain a copy of the License at:
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
local reconf = config['regexp']
local rspamd_regexp = require "rspamd_regexp"
-- Messages that have only HTML part
reconf['MIME_HTML_ONLY'] = {
re = 'has_only_html_part()',
score = 0.2,
description = 'Messages that have only HTML part',
group = 'headers'
}
local function has_anchor_parent(tag)
local parent = tag
repeat
parent = parent:get_parent()
if parent then
if parent:get_type() == 'a' then
return true
end
end
until not parent
return false
end
local function check_html_image(task, min, max)
local tp = task:get_text_parts()
for _,p in ipairs(tp) do
if p:is_html() then
local hc = p:get_html()
local len = p:get_length()
if hc and len >= min and len < max then
local images = hc:get_images()
if images then
for _,i in ipairs(images) do
local tag = i['tag']
if tag then
if has_anchor_parent(tag) then
-- do not trigger on small and unknown size images
if i['height'] + i['width'] >= 210 and i['embedded'] then
return true
end
end
end
end
end
end
end
end
end
rspamd_config.HTML_SHORT_LINK_IMG_1 = {
callback = function(task)
return check_html_image(task, 0, 1024)
end,
score = 2.0,
group = 'html',
description = 'Short html part (0..1K) with a link to an image'
}
rspamd_config.HTML_SHORT_LINK_IMG_2 = {
callback = function(task)
return check_html_image(task, 1024, 1536)
end,
score = 1.0,
group = 'html',
description = 'Short html part (1K..1.5K) with a link to an image'
}
rspamd_config.HTML_SHORT_LINK_IMG_3 = {
callback = function(task)
return check_html_image(task, 1536, 2048)
end,
score = 0.5,
group = 'html',
description = 'Short html part (1.5K..2K) with a link to an image'
}
rspamd_config.R_EMPTY_IMAGE = {
callback = function(task)
local tp = task:get_text_parts() -- get text parts in a message
for _,p in ipairs(tp) do -- iterate over text parts array using `ipairs`
if p:is_html() then -- if the current part is html part
local hc = p:get_html() -- we get HTML context
local len = p:get_length() -- and part's length
if hc and len < 50 then -- if we have a part that has less than 50 bytes of text
local images = hc:get_images() -- then we check for HTML images
if images then -- if there are images
for _,i in ipairs(images) do -- then iterate over images in the part
if i['height'] + i['width'] >= 400 then -- if we have a large image
local tag = i['tag']
if tag then
if not has_anchor_parent(tag) then
return true
end
end
end
end
end
end
end
end
end,
score = 2.0,
group = 'html',
description = 'Message contains empty parts and image'
}
rspamd_config.R_SUSPICIOUS_IMAGES = {
callback = function(task)
local tp = task:get_text_parts() -- get text parts in a message
for _, p in ipairs(tp) do
local h = p:get_html()
if h then
local l = p:get_words_count()
local img = h:get_images()
local pic_words = 0
if img then
for _, i in ipairs(img) do
local dim = i['width'] + i['height']
local tag = i['tag']
if tag then
if has_anchor_parent(tag) then
if dim > 100 and dim < 3000 then
-- We assume that a single picture 100x200 contains approx 3 words of text
pic_words = pic_words + dim / 100
end
end
end
end
end
if l + pic_words > 0 then
local rel = pic_words / (l + pic_words)
if rel > 0.5 then
return true, (rel - 0.5) * 2
end
end
end
end
return false
end,
score = 5.0,
group = 'html',
description = 'Message contains many suspicious messages'
}
local vis_check_id = rspamd_config:register_symbol{
name = 'HTML_VISIBLE_CHECKS',
type = 'callback',
group = 'html',
callback = function(task)
--local logger = require "rspamd_logger"
local tp = task:get_text_parts() -- get text parts in a message
local ret = false
local transp_rate = 0
local invisible_blocks = 0
local zero_size_blocks = 0
local arg
local normal_len = 0
local transp_len = 0
for _,p in ipairs(tp) do -- iterate over text parts array using `ipairs`
normal_len = normal_len + p:get_length()
if p:is_html() and p:get_html() then -- if the current part is html part
local hc = p:get_html() -- we get HTML context
hc:foreach_tag({'font', 'span', 'div', 'p', 'td'}, function(tag, clen, is_leaf)
local bl = tag:get_style()
if bl then
if not bl.visible and is_leaf then
invisible_blocks = invisible_blocks + 1
end
if (bl.font_size or 12) == 0 and is_leaf then
zero_size_blocks = zero_size_blocks + 1
end
if bl.transparent and is_leaf then
ret = true
invisible_blocks = invisible_blocks + 1 -- This block is invisible
transp_len = transp_len + clen
normal_len = normal_len - clen
local tr = transp_len / (normal_len + transp_len)
if tr > transp_rate then
transp_rate = tr
if not bl.color then bl.color = {0, 0, 0} end
if not bl.bgcolor then bl.bgcolor = {0, 0, 0} end
arg = string.format('%s color #%x%x%x bgcolor #%x%x%x',
tag:get_type(),
bl.color[1], bl.color[2], bl.color[3],
bl.bgcolor[1], bl.bgcolor[2], bl.bgcolor[3])
end
end
end
return false -- Continue search
end)
end
end
if ret then
transp_rate = transp_len / (normal_len + transp_len)
if transp_rate > 0.1 then
if transp_rate > 0.5 or transp_rate ~= transp_rate then
transp_rate = 0.5
end
task:insert_result('R_WHITE_ON_WHITE', (transp_rate * 2.0), arg)
end
end
if invisible_blocks > 0 then
if invisible_blocks > 10 then
invisible_blocks = 10
end
local rates = { -- From 1 to 10
0.05,
0.1,
0.2,
0.3,
0.4,
0.5,
0.6,
0.7,
0.8,
1.0,
}
task:insert_result('MANY_INVISIBLE_PARTS', rates[invisible_blocks],
tostring(invisible_blocks))
end
if zero_size_blocks > 0 then
if zero_size_blocks > 5 then
if zero_size_blocks > 10 then
-- Full score
task:insert_result('ZERO_FONT', 1.0,
tostring(zero_size_blocks))
else
zero_size_blocks = 5
end
end
if zero_size_blocks <= 5 then
local rates = { -- From 1 to 5
0.1,
0.2,
0.2,
0.3,
0.5,
}
task:insert_result('ZERO_FONT', rates[zero_size_blocks],
tostring(zero_size_blocks))
end
end
end,
}
rspamd_config:register_symbol{
type = 'virtual',
parent = vis_check_id,
name = 'R_WHITE_ON_WHITE',
description = 'Message contains low contrast text',
score = 4.0,
group = 'html',
one_shot = true,
}
rspamd_config:register_symbol{
type = 'virtual',
parent = vis_check_id,
name = 'ZERO_FONT',
description = 'Zero sized font used',
score = 1.0, -- Reached if more than 5 elements have zero size
one_shot = true,
group = 'html'
}
rspamd_config:register_symbol{
type = 'virtual',
parent = vis_check_id,
name = 'MANY_INVISIBLE_PARTS',
description = 'Many parts are visually hidden',
score = 1.0, -- Reached if more than 10 elements are hidden
one_shot = true,
group = 'html'
}
rspamd_config.EXT_CSS = {
callback = function(task)
local regexp_lib = require "rspamd_regexp"
local re = regexp_lib.create_cached('/^.*\\.css(?:[?#].*)?$/i')
local tp = task:get_text_parts() -- get text parts in a message
local ret = false
for _,p in ipairs(tp) do -- iterate over text parts array using `ipairs`
if p:is_html() and p:get_html() then -- if the current part is html part
local hc = p:get_html() -- we get HTML context
hc:foreach_tag({'link'}, function(tag)
local bl = tag:get_extra()
if bl then
local s = tostring(bl)
if s and re:match(s) then
ret = true
end
end
return ret -- Continue search
end)
end
end
return ret
end,
score = 1.0,
group = 'html',
description = 'Message contains external CSS reference'
}
local https_re = rspamd_regexp.create_cached('/^https:/i')
rspamd_config.HTTP_TO_HTTPS = {
callback = function(task)
local found_opts
local tp = task:get_text_parts() or {}
for _,p in ipairs(tp) do
if p:is_html() then
local hc = p:get_html()
if (not hc) then return false end
local found = false
hc:foreach_tag('a', function (tag, _)
-- Skip this loop if we already have a match
if (found) then return true end
local c = tag:get_content()
if (c) then
if (not https_re:match(c)) then return false end
local u = tag:get_extra()
if (not u) then return false end
local url_proto = u:get_protocol()
if url_proto ~= 'http' then return false end
-- Capture matches for http in href to https in visible part only
found = true
found_opts = u:get_host()
return true
end
return false
end)
if (found) then
return true,1.0,found_opts
end
return false
end
end
return false
end,
description = 'Anchor text contains different scheme to target URL',
score = 2.0,
group = 'html'
}
rspamd_config.HTTP_TO_IP = {
callback = function(task)
local tp = task:get_text_parts()
if (not tp) then return false end
for _,p in ipairs(tp) do
if p:is_html() then
local hc = p:get_html()
if (not hc) then return false end
local found = false
hc:foreach_tag('a', function (tag, length)
if (found) then return true end
local u = tag:get_extra()
if (u) then
u = tostring(u):lower()
if (u:match('^https?://%d+%.%d+%.%d+%.%d+')) then
found = true
end
end
return false
end)
if found then return true end
return false
end
end
end,
description = 'Anchor points to an IP address',
score = 1.0,
group = 'html'
}
|