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--[[
Copyright (c) 2011-2015, Vsevolod Stakhov <vsevolod@highsecure.ru>
Licensed 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.
]]--
-- This is main lua config file for rspamd
local util = require "rspamd_util"
local rspamd_regexp = require "rspamd_regexp"
local rspamd_logger = require "rspamd_logger"
local reconf = config['regexp']
-- Uncategorized rules
local subject_re = rspamd_regexp.create('/^(?:(?:Re|Fwd|Fw|Aw|Antwort|Sv):\\s*)+(.+)$/i')
-- Local rules
local r_bgcolor = '/BGCOLOR=/iP'
local r_font_color = '/font color=[\\"\']?\\#FFFFFF[\\"\']?/iP'
reconf['R_WHITE_ON_WHITE'] = string.format('(!(%s) & (%s))', r_bgcolor, r_font_color)
reconf['R_FLASH_REDIR_IMGSHACK'] = '/^(?:http:\\/\\/)?img\\d{1,5}\\.imageshack\\.us\\/\\S+\\.swf/U'
-- Local functions
-- Subject issues
local function test_subject(task, check_function, rate)
local function normalize_linear(a, x)
local f = a * x
return true, (( f < 1 ) and f or 1), tostring(x)
end
local sbj = task:get_header('Subject')
if sbj then
local stripped_subject = subject_re:search(sbj, false, true)
if stripped_subject and stripped_subject[1] and stripped_subject[1][2] then
sbj = stripped_subject[1][2]
end
local l = util.strlen_utf8(sbj)
if check_function(sbj, l) then
return normalize_linear(rate, l)
end
end
return false
end
rspamd_config.SUBJ_ALL_CAPS = {
callback = function(task)
local caps_test = function(sbj, len)
return util.is_uppercase(sbj)
end
return test_subject(task, caps_test, 1.0/40.0)
end,
score = 3.0,
group = 'subject',
description = 'All capital letters in subject'
}
rspamd_config.LONG_SUBJ = {
callback = function(task)
local length_test = function(sbj, len)
return len > 200
end
return test_subject(task, length_test, 1.0/400.0)
end,
score = 3.0,
group = 'subject',
description = 'Subject is too long'
}
-- Different text parts
rspamd_config.R_PARTS_DIFFER = function(task)
local distance = task:get_mempool():get_variable('parts_distance', 'double')
if distance then
local nd = tonumber(distance)
-- ND is relation of different words to total words
if nd >= 0.5 then
local tw = task:get_mempool():get_variable('total_words', 'int')
if tw then
local score
if tw > 30 then
-- We are confident about difference
score = (nd - 0.5) * 2.0
else
-- We are not so confident about difference
score = (nd - 0.5)
end
task:insert_result('R_PARTS_DIFFER', score, tostring(100.0 * nd) .. '%')
end
end
end
return false
end
-- Date issues
rspamd_config.MISSING_DATE = function(task)
if rspamd_config:get_api_version() >= 5 then
local date = task:get_header_raw('Date')
if date == nil or date == '' then
return true
end
end
return false
end
rspamd_config.DATE_IN_FUTURE = function(task)
if rspamd_config:get_api_version() >= 5 then
local dm = task:get_date{format = 'message'}
local dt = task:get_date{format = 'connect'}
-- An 2 hour
if dm > 0 and dm - dt > 7200 then
return true
end
end
return false
end
rspamd_config.DATE_IN_PAST = function(task)
if rspamd_config:get_api_version() >= 5 then
local dm = task:get_date{format = 'message', gmt = true}
local dt = task:get_date{format = 'connect', gmt = true}
-- A day
if dm > 0 and dt - dm > 86400 then
return true
end
end
return false
end
rspamd_config.R_SUSPICIOUS_URL = function(task)
local urls = task:get_urls()
if urls then
for i,u in ipairs(urls) do
if u:is_obscured() then
task:insert_result('R_SUSPICIOUS_URL', 1.0, u:get_host())
end
end
end
return false
end
rspamd_config.BROKEN_HEADERS = {
callback = function(task)
if task:has_flag('broken_headers') then
return true
end
return false
end,
score = 1.0,
group = 'header',
description = 'Headers structure is likely broken'
}
rspamd_config.HEADER_RCONFIRM_MISMATCH = {
callback = function (task)
local header_from = nil
local cread = task:get_header('X-Confirm-Reading-To')
if task:has_from('mime') then
header_from = task:get_from('mime')[1]
end
local header_cread = nil
if cread then
local headers_cread = util.parse_mail_address(cread)
if headers_cread then header_cread = headers_cread[1] end
end
if header_from and header_cread then
if not string.find(header_from['addr'], header_cread['addr']) then
return true
end
end
return false
end,
score = 2.0,
group = 'header',
description = 'Read confirmation address is different to from address'
}
rspamd_config.HEADER_FORGED_MDN = {
callback = function (task)
local mdn = task:get_header('Disposition-Notification-To')
local header_rp = nil
if task:has_from('smtp') then
header_rp = task:get_from('smtp')[1]
end
-- Parse mail addr
local header_mdn = nil
if mdn then
local headers_mdn = util.parse_mail_address(mdn)
if headers_mdn then header_mdn = headers_mdn[1] end
end
if header_mdn and not header_rp then return true end
if header_rp and not header_mdn then return false end
if header_mdn and header_mdn['addr'] ~= header_rp['addr'] then
return true
end
return false
end,
score = 2.0,
group = 'header',
description = 'Read confirmation address is different to return path'
}
local headers_unique = {
'Content-Type',
'Content-Transfer-Encoding',
-- https://tools.ietf.org/html/rfc5322#section-3.6
'Date',
'From',
'Sender',
'Reply-To',
'To',
'Cc',
'Bcc',
'Message-ID',
'In-Reply-To',
'References',
'Subject'
}
rspamd_config.MULTIPLE_UNIQUE_HEADERS = {
callback = function (task)
local res = 0
local res_tbl = {}
for i,hdr in ipairs(headers_unique) do
local h = task:get_header_full(hdr)
if h and #h > 1 then
res = res + 1
table.insert(res_tbl, hdr)
end
end
if res > 0 then
return true,res,table.concat(res_tbl, ',')
end
return false
end,
score = 5.0,
group = 'header',
description = 'Repeated unique headers'
}
rspamd_config.ENVFROM_PRVS = {
callback = function (task)
-- Detect PRVS/BATV addresses to avoid FORGED_SENDER
-- https://en.wikipedia.org/wiki/Bounce_Address_Tag_Validation
if not (task:has_from(1) and task:has_from(2)) then
return false
end
local envfrom = task:get_from(1)
local tag,ef = envfrom[1].addr:lower():match("^prvs=([^=]+)=(.+)$")
if not ef then return false end
-- See if it matches the From header
local from = task:get_from(2)
if ef == from[1].addr:lower() then
return true
end
return false
end,
score = 0.01,
description = "Envelope From is a PRVS address that matches the From address",
group = 'prvs'
}
rspamd_config.ENVFROM_VERP = {
callback = function (task)
if not (task:has_from(1) and task:has_recipients(1)) then
return false
end
local envfrom = task:get_from(1)
local envrcpts = task:get_recipients(1)
-- VERP only works for single recipient messages
if table.getn(envrcpts) > 1 then return false end
-- Get recipient and compute VERP address
local rcpt = envrcpts[1].addr:lower()
local verp = rcpt:gsub('@','=')
-- Get the user portion of the envfrom
local ef_user = envfrom[1].user:lower()
-- See if the VERP representation of the recipient appears in it
if ef_user:find(verp, 1, true)
and not ef_user:find('+caf_=' .. verp, 1, true) -- Google Forwarding
and not ef_user:find('^srs[01]=') -- SRS
then
return true
end
return false
end,
score = 0.01,
description = "Envelope From is a VERP address",
group = "mailing_list"
}
rspamd_config.RCVD_TLS_ALL = {
callback = function (task)
local rcvds = task:get_header_full('Received')
if not rcvds then return false end
local count = 0
local encrypted = 0
for _, rcvd in ipairs(rcvds) do
count = count + 1
local r = rcvd['decoded']:lower()
local by = r:match('^by%s+([^%s]+)') or r:match('%sby%s+([^%s]+)')
local with = r:match('%swith%s+(e?smtps?a?)')
if with and with:match('esmtps') then
encrypted = encrypted + 1
end
end
if (count > 0 and count == encrypted) then
return true
end
end,
score = 0.01,
description = "All hops used encrypted transports",
group = "encryption"
}
rspamd_config.MISSING_FROM = {
callback = function(task)
local from = task:get_header('From')
if from == nil or from == '' then
return true
end
return false
end,
score = 2.0,
group = 'header',
description = 'Missing From: header'
}
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