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--[[
Copyright (c) 2011-2017, 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 fun = require "fun"
local util = require "rspamd_util"
local rspamd_regexp = require "rspamd_regexp"
-- Different text parts
rspamd_config.R_PARTS_DIFFER = {
callback = 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,
string.format('%.1f%%', tostring(100.0 * nd)))
end
end
end
return false
end,
score = 1.0,
description = 'Text and HTML parts differ',
group = 'body'
}
-- Date issues
rspamd_config.MISSING_DATE = {
callback = 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,
score = 1.0,
description = 'Message date is missing',
group = 'date'
}
rspamd_config.DATE_IN_FUTURE = {
callback = 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}
-- 2 hours
if dm > 0 and dm - dt > 7200 then
return true
end
end
return false
end,
score = 4.0,
description = 'Message date is in future',
group = 'date'
}
rspamd_config.DATE_IN_PAST = {
callback = 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,
score = 1.0,
description = 'Message date is in past',
group = 'date'
}
rspamd_config.R_SUSPICIOUS_URL = {
callback = function(task)
local urls = task:get_urls()
if urls then
for _,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,
score = 5.0,
one_shot = true,
description = 'Obfusicated or suspicious URL has been found in a message',
group = 'url'
}
rspamd_config.ENVFROM_PRVS = {
callback = function (task)
--[[
Detect PRVS/BATV addresses to avoid FORGED_SENDER
https://en.wikipedia.org/wiki/Bounce_Address_Tag_Validation
Signature syntax:
prvs=TAG=USER@example.com BATV draft (https://tools.ietf.org/html/draft-levine-smtp-batv-01)
prvs=USER=TAG@example.com
btv1==TAG==USER@example.com Barracuda appliance
msprvs1=TAG=USER@example.com Sparkpost email delivery service
]]--
if not (task:has_from(1) and task:has_from(2)) then
return false
end
local envfrom = task:get_from(1)
local re_text = '^(?:(prvs|msprvs1)=([^=]+)=|btv1==[^=]+==)(.+@(.+))$'
local re = rspamd_regexp.create_cached(re_text)
local c = re:search(envfrom[1].addr:lower(), false, true)
if not c then return false end
local ef = c[1][4]
-- See if it matches the From header
local from = task:get_from(2)
if ef == from[1].addr:lower() then
return true
end
-- Check for prvs=USER=TAG@example.com
local t = c[1][2]
if t == 'prvs' then
local efr = c[1][3] .. '@' .. c[1][5]
if efr == from[1].addr:lower() then
return true
end
end
return false
end,
score = 0.0,
description = "Envelope From is a PRVS address that matches the From address",
group = 'prvs'
}
rspamd_config.ENVFROM_VERP = {
callback = function (task)
if not (task:has_from(1) and task:has_recipients(1)) then
return false
end
local envfrom = task:get_from(1)
local envrcpts = task:get_recipients(1)
-- VERP only works for single recipient messages
if #envrcpts > 1 then return false end
-- Get recipient and compute VERP address
local rcpt = envrcpts[1].addr:lower()
local verp = rcpt:gsub('@','=')
-- Get the user portion of the envfrom
local ef_user = envfrom[1].user:lower()
-- See if the VERP representation of the recipient appears in it
if ef_user:find(verp, 1, true)
and not ef_user:find('+caf_=' .. verp, 1, true) -- Google Forwarding
and not ef_user:find('^srs[01]=') -- SRS
then
return true
end
return false
end,
score = 0.0,
description = "Envelope From is a VERP address",
group = "mailing_list"
}
rspamd_config.RCVD_TLS_ALL = {
callback = function (task)
local rcvds = task:get_header_full('Received')
if not rcvds then return false end
local ret = fun.all(function(rc)
return rc.flags and (rc.flags['ssl'] or rc.flags['authenticated'])
end, rcvds)
return ret
end,
score = 0.0,
description = "All hops used encrypted transports",
group = "encryption"
}
rspamd_config.RCVD_HELO_USER = {
callback = function (task)
-- Check HELO argument from MTA
local helo = task:get_helo()
if (helo and helo:lower():find('^user$')) then
return true
end
-- Check Received headers
local rcvds = task:get_header_full('Received')
if not rcvds then return false end
for _, rcvd in ipairs(rcvds) do
local r = rcvd['decoded']:lower()
if (r:find("^%s*from%suser%s")) then return true end
if (r:find("helo[%s=]user[%s%)]")) then return true end
end
end,
description = 'HELO User spam pattern',
score = 3.0
}
rspamd_config.URI_COUNT_ODD = {
callback = function (task)
local ct = task:get_header('Content-Type')
if (ct and ct:lower():find('^multipart/alternative')) then
local urls = task:get_urls() or {}
local nurls = fun.filter(function(url)
return not url:is_html_displayed()
end, urls):foldl(function(acc, val) return acc + 1 end, 0)
if nurls % 2 == 1 then
return true, 1.0, tostring(nurls)
end
end
end,
description = 'Odd number of URIs in multipart/alternative message',
score = 1.0
}
rspamd_config.HAS_ATTACHMENT = {
callback = function (task)
local parts = task:get_parts()
if parts and #parts > 1 then
for _, p in ipairs(parts) do
local cd = p:get_header('Content-Disposition')
if (cd and cd:lower():match('^attachment')) then
return true
end
end
end
end,
description = 'Message contains attachments'
}
-- Requires freemail maps loaded in multimap
local function freemail_reply_neq_from(task)
local frt = task:get_symbol('FREEMAIL_REPLYTO')
local ff = task:get_symbol('FREEMAIL_FROM')
if (frt and ff and frt['options'] and ff['options'] and
frt['options'][1] ~= ff['options'][1])
then
return true
end
return false
end
local freemail_reply_neq_from_id = rspamd_config:register_symbol({
name = 'FREEMAIL_REPLYTO_NEQ_FROM_DOM',
callback = freemail_reply_neq_from,
description = 'Freemail From and Reply-To, but to different Freemail services',
score = 3.0
})
rspamd_config:register_dependency(freemail_reply_neq_from_id, 'FREEMAIL_REPLYTO')
rspamd_config:register_dependency(freemail_reply_neq_from_id, 'FREEMAIL_FROM')
rspamd_config.OMOGRAPH_URL = {
callback = function(task)
local urls = task:get_urls()
if urls then
local bad_omographs = 0
local bad_urls = {}
fun.each(function(u)
local h1 = u:get_host()
local h2 = u:get_phished():get_host()
if h1 and h2 then
if util.is_utf_spoofed(h1, h2) then
table.insert(bad_urls, string.format('%s->%s', h1, h2))
bad_omographs = bad_omographs + 1
end
end
end, fun.filter(function(u) return u:is_phished() end, urls))
if bad_omographs > 0 then
if bad_omographs > 1 then bad_omographs = 1.0 end
return true, bad_omographs, bad_urls
end
end
return false
end,
score = 5.0,
description = 'Url contains both latin and non-latin characters'
}
local aliases_id = rspamd_config:register_symbol{
type = 'prefilter',
name = 'EMAIL_PLUS_ALIASES',
callback = function(task)
local function check_address(addr)
if addr.user then
local cap, pluses = string.match(addr.user, '^([^%+][^%+]*)(%+.*)$')
if cap then
return cap, rspamd_str_split(pluses, '+')
end
end
return nil
end
local function set_addr(addr, new_user)
addr.user = new_user
if addr.domain then
addr.addr = string.format('%s@%s', addr.user, addr.domain)
else
addr.addr = string.format('%s@', addr.user)
end
if addr.name then
addr.raw = string.format('%s <%s>', addr.name, addr.addr)
else
addr.raw = string.format('<%s>', addr.addr)
end
end
local function check_from(type)
if task:has_from(type) then
local addr = task:get_from(type)[1]
local na,tags = check_address(addr)
if na then
set_addr(addr, na)
task:set_from(type, addr)
task:insert_result('TAGGED_FROM', 1.0, fun.totable(
fun.filter(function(t) return t and #t > 0 end, tags)))
end
end
end
check_from('smtp')
check_from('mime')
local function check_rcpt(type)
if task:has_recipients(type) then
local modified = false
local all_tags = {}
local addrs = task:get_recipients(type)
for _, addr in ipairs(addrs) do
local na,tags = check_address(addr)
if na then
set_addr(addr, na)
modified = true
fun.each(function(t) table.insert(all_tags, t) end,
fun.filter(function(t) return t and #t > 0 end, tags))
end
end
if modified then
task:set_recipients(type, addrs)
task:insert_result('TAGGED_RCPT', 1.0, all_tags)
end
end
end
check_rcpt('smtp')
check_rcpt('mime')
end,
priority = 150,
description = 'Removes plus aliases from the email',
}
rspamd_config:register_symbol{
type = 'virtual',
parent = aliases_id,
name = 'TAGGED_RCPT',
description = 'SMTP recipients have plus tags',
score = 0,
}
rspamd_config:register_symbol{
type = 'virtual',
parent = aliases_id,
name = 'TAGGED_FROM',
description = 'SMTP from has plus tags',
score = 0,
}
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