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Diffstat (limited to 'lualib/lua_scanners/virustotal.lua')
| -rw-r--r-- | lualib/lua_scanners/virustotal.lua | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/lualib/lua_scanners/virustotal.lua b/lualib/lua_scanners/virustotal.lua new file mode 100644 index 0000000..d937c41 --- /dev/null +++ b/lualib/lua_scanners/virustotal.lua @@ -0,0 +1,214 @@ +--[[ +Copyright (c) 2022, Vsevolod Stakhov <vsevolod@rspamd.com> + +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. +]]-- + +--[[[ +-- @module virustotal +-- This module contains Virustotal integration support +-- https://www.virustotal.com/ +--]] + +local lua_util = require "lua_util" +local http = require "rspamd_http" +local rspamd_cryptobox_hash = require "rspamd_cryptobox_hash" +local rspamd_logger = require "rspamd_logger" +local common = require "lua_scanners/common" + +local N = 'virustotal' + +local function virustotal_config(opts) + + local default_conf = { + name = N, + url = 'https://www.virustotal.com/vtapi/v2/file', + timeout = 5.0, + log_clean = false, + retransmits = 1, + cache_expire = 7200, -- expire redis in 2h + message = '${SCANNER}: spam message found: "${VIRUS}"', + detection_category = "virus", + default_score = 1, + action = false, + scan_mime_parts = true, + scan_text_mime = false, + scan_image_mime = false, + apikey = nil, -- Required to set by user + -- Specific for virustotal + minimum_engines = 3, -- Minimum required to get scored + full_score_engines = 7, -- After this number we set max score + } + + default_conf = lua_util.override_defaults(default_conf, opts) + + if not default_conf.prefix then + default_conf.prefix = 'rs_' .. default_conf.name .. '_' + end + + if not default_conf.log_prefix then + if default_conf.name:lower() == default_conf.type:lower() then + default_conf.log_prefix = default_conf.name + else + default_conf.log_prefix = default_conf.name .. ' (' .. default_conf.type .. ')' + end + end + + if not default_conf.apikey then + rspamd_logger.errx(rspamd_config, 'no apikey defined for virustotal, disable checks') + + return nil + end + + lua_util.add_debug_alias('external_services', default_conf.name) + return default_conf +end + +local function virustotal_check(task, content, digest, rule, maybe_part) + local function virustotal_check_uncached() + local function make_url(hash) + return string.format('%s/report?apikey=%s&resource=%s', + rule.url, rule.apikey, hash) + end + + local hash = rspamd_cryptobox_hash.create_specific('md5') + hash:update(content) + hash = hash:hex() + + local url = make_url(hash) + lua_util.debugm(N, task, "send request %s", url) + local request_data = { + task = task, + url = url, + timeout = rule.timeout, + } + + local function vt_http_callback(http_err, code, body, headers) + if http_err then + rspamd_logger.errx(task, 'HTTP error: %s, body: %s, headers: %s', http_err, body, headers) + else + local cached + local dyn_score + -- Parse the response + if code ~= 200 then + if code == 404 then + cached = 'OK' + if rule['log_clean'] then + rspamd_logger.infox(task, '%s: hash %s clean (not found)', + rule.log_prefix, hash) + else + lua_util.debugm(rule.name, task, '%s: hash %s clean (not found)', + rule.log_prefix, hash) + end + elseif code == 204 then + -- Request rate limit exceeded + rspamd_logger.infox(task, 'virustotal request rate limit exceeded') + task:insert_result(rule.symbol_fail, 1.0, 'rate limit exceeded') + return + else + rspamd_logger.errx(task, 'invalid HTTP code: %s, body: %s, headers: %s', code, body, headers) + task:insert_result(rule.symbol_fail, 1.0, 'Bad HTTP code: ' .. code) + return + end + else + local ucl = require "ucl" + local parser = ucl.parser() + local res, json_err = parser:parse_string(body) + + lua_util.debugm(rule.name, task, '%s: got reply data: "%s"', + rule.log_prefix, body) + + if res then + local obj = parser:get_object() + if not obj.positives or type(obj.positives) ~= 'number' then + if obj.response_code then + if obj.response_code == 0 then + cached = 'OK' + if rule['log_clean'] then + rspamd_logger.infox(task, '%s: hash %s clean (not found)', + rule.log_prefix, hash) + else + lua_util.debugm(rule.name, task, '%s: hash %s clean (not found)', + rule.log_prefix, hash) + end + else + rspamd_logger.errx(task, 'invalid JSON reply: %s, body: %s, headers: %s', + 'bad response code: ' .. tostring(obj.response_code), body, headers) + task:insert_result(rule.symbol_fail, 1.0, 'Bad JSON reply: no `positives` element') + return + end + else + rspamd_logger.errx(task, 'invalid JSON reply: %s, body: %s, headers: %s', + 'no response_code', body, headers) + task:insert_result(rule.symbol_fail, 1.0, 'Bad JSON reply: no `positives` element') + return + end + else + if obj.positives < rule.minimum_engines then + lua_util.debugm(rule.name, task, '%s: hash %s has not enough hits: %s where %s is min', + rule.log_prefix, obj.positives, rule.minimum_engines) + -- TODO: add proper hashing! + cached = 'OK' + else + if obj.positives > rule.full_score_engines then + dyn_score = 1.0 + else + local norm_pos = obj.positives - rule.minimum_engines + dyn_score = norm_pos / (rule.full_score_engines - rule.minimum_engines) + end + + if dyn_score < 0 or dyn_score > 1 then + dyn_score = 1.0 + end + local sopt = string.format("%s:%s/%s", + hash, obj.positives, obj.total) + common.yield_result(task, rule, sopt, dyn_score, nil, maybe_part) + cached = sopt + end + end + else + -- not res + rspamd_logger.errx(task, 'invalid JSON reply: %s, body: %s, headers: %s', + json_err, body, headers) + task:insert_result(rule.symbol_fail, 1.0, 'Bad JSON reply: ' .. json_err) + return + end + end + + if cached then + common.save_cache(task, digest, rule, cached, dyn_score, maybe_part) + end + end + end + + request_data.callback = vt_http_callback + http.request(request_data) + end + + if common.condition_check_and_continue(task, content, rule, digest, + virustotal_check_uncached) then + return + else + + virustotal_check_uncached() + end + +end + +return { + type = 'antivirus', + description = 'Virustotal integration', + configure = virustotal_config, + check = virustotal_check, + name = N +} |