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--[[
Copyright (c) 2018, Vsevolod Stakhov <vsevolod@highsecure.ru>
Copyright (c) 2018, Carsten Rosenberg <c.rosenberg@heinlein-support.de>
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 oletools
-- This module contains oletools access functions
--]]
local lua_util = require "lua_util"
local tcp = require "rspamd_tcp"
local upstream_list = require "rspamd_upstream_list"
local rspamd_logger = require "rspamd_logger"
local ucl = require "ucl"
local common = require "lua_scanners/common"
local fun = require "fun"
local module_name = 'oletools'
local function oletools_check(task, content, digest, rule)
local function oletools_check_uncached ()
local upstream = rule.upstreams:get_upstream_round_robin()
local addr = upstream:get_addr()
local retransmits = rule.retransmits
local function oletools_callback(err, data, conn)
local function oletools_requery()
-- set current upstream to fail because an error occurred
upstream:fail()
-- retry with another upstream until retransmits exceeds
if retransmits > 0 then
retransmits = retransmits - 1
lua_util.debugm(rule.module_name, task, '%s: Request Error: %s - retries left: %s',
rule.log_prefix, err, retransmits)
-- Select a different upstream!
upstream = rule.upstreams:get_upstream_round_robin()
addr = upstream:get_addr()
lua_util.debugm(rule.module_name, task, '%s: retry IP: %s:%s',
rule.log_prefix, addr, addr:get_port())
tcp.request({
task = task,
host = addr:to_string(),
port = addr:get_port(),
timeout = rule['timeout'],
shutdown = true,
data = content,
callback = oletools_callback,
})
else
rspamd_logger.errx(task, '%s: failed to scan, maximum retransmits '..
'exceed', rule.log_prefix)
task:insert_result(rule['symbol_fail'], 0.0, 'failed to scan and '..
'retransmits exceed')
end
end
if err then
oletools_requery()
else
-- Parse the response
if upstream then upstream:ok() end
data = tostring(data)
local ucl_parser = ucl.parser()
local ok, ucl_err = ucl_parser:parse_string(tostring(data))
if not ok then
rspamd_logger.errx(task, "%s: error parsing json response: %s",
rule.log_prefix, ucl_err)
return
end
local result = ucl_parser:get_object()
local oletools_rc = {
[0] = 'RETURN_OK',
[1] = 'RETURN_WARNINGS',
[2] = 'RETURN_WRONG_ARGS',
[3] = 'RETURN_FILE_NOT_FOUND',
[4] = 'RETURN_XGLOB_ERR',
[5] = 'RETURN_OPEN_ERROR',
[6] = 'RETURN_PARSE_ERROR',
[7] = 'RETURN_SEVERAL_ERRS',
[8] = 'RETURN_UNEXPECTED',
[9] = 'RETURN_ENCRYPTED',
}
--lua_util.debugm(rule.module_name, task, '%s: result: %s', rule.log_prefix, result)
lua_util.debugm(rule.module_name, task, '%s: filename: %s', rule.log_prefix, result[2]['file'])
lua_util.debugm(rule.module_name, task, '%s: type: %s', rule.log_prefix, result[2]['type'])
if result[1].error ~= nil then
rspamd_logger.errx(task, '%s: ERROR found: %s', rule.log_prefix,
result[1].error)
oletools_requery()
elseif result[3]['return_code'] == 9 then
rspamd_logger.warnx(task, '%s: File is encrypted.', rule.log_prefix)
elseif result[3]['return_code'] > 6 then
rspamd_logger.errx(task, '%s: Error Returned: %s',
rule.log_prefix, oletools_rc[result[3]['return_code']])
elseif result[3]['return_code'] > 1 then
rspamd_logger.errx(task, '%s: Error Returned: %s',
rule.log_prefix, oletools_rc[result[3]['return_code']])
oletools_requery()
elseif result[2]['analysis'] == 'null' and #result[2]['macros'] == 0 then
if rule.log_clean == true then
rspamd_logger.infox(task, '%s: Scanned Macro is OK', rule.log_prefix)
else
lua_util.debugm(rule.module_name, task, '%s: No Macro found', rule.log_prefix)
end
elseif #result[2]['macros'] > 0 then
for _,m in ipairs(result[2]['macros']) do
lua_util.debugm(rule.module_name, task, '%s: macros found - code: %s, ole_stream: %s, '..
'vba_filename: %s', rule.log_prefix, m.code, m.ole_stream, m.vba_filename)
end
local macro_autoexec = false
local macro_suspicious = false
local macro_keyword_table = {}
for _,a in ipairs(result[2]['analysis']) do
if a.type ~= 'AutoExec' or a.type ~= 'Suspicious' then
lua_util.debugm(rule.module_name, task, '%s: threat found - type: %s, keyword: %s, '..
'description: %s', rule.log_prefix, a.type, a.keyword, a.description)
end
if a.type == 'AutoExec' then
macro_autoexec = true
if rule.extended == true then
table.insert(macro_keyword_table, a.keyword)
end
elseif a.type == 'Suspicious'
and a.keyword ~= 'Base64 Strings'
and a.keyword ~= 'Hex Strings'
then
macro_suspicious = true
if rule.extended == true then
table.insert(macro_keyword_table, a.keyword)
end
end
end
if macro_autoexec then
table.insert(macro_keyword_table, 'AutoExec')
end
if macro_suspicious then
table.insert(macro_keyword_table, 'Suspicious')
end
lua_util.debugm(rule.module_name, task, '%s: extended: %s', rule.log_prefix, rule.extended)
if rule.extended == false and macro_autoexec and macro_suspicious then
lua_util.debugm(rule.module_name, task, '%s: found macro_autoexec and '..
'macro_suspicious', rule.log_prefix)
local threat = 'AutoExec+Suspicious'
common.yield_result(task, rule, threat, rule.default_score)
common.save_av_cache(task, digest, rule, threat, rule.default_score)
elseif rule.extended == true and #macro_keyword_table > 0 then
common.yield_result(task, rule, macro_keyword_table, rule.default_score)
common.save_av_cache(task, digest, rule, macro_keyword_table, rule.default_score)
elseif rule.log_clean == true then
rspamd_logger.infox(task, '%s: Scanned Macro is OK', rule.log_prefix)
end
else
rspamd_logger.warnx(task, '%s: unhandled response', rule.log_prefix)
end
end
end
tcp.request({
task = task,
host = addr:to_string(),
port = addr:get_port(),
timeout = rule['timeout'],
shutdown = true,
data = content,
callback = oletools_callback,
})
end
if common.need_av_check(task, content, rule) then
if common.check_av_cache(task, digest, rule, oletools_check_uncached) then
return
else
oletools_check_uncached()
end
end
end
local function oletools_config(opts)
local oletools_conf = {
module_name = module_name,
scan_mime_parts = false,
scan_text_mime = false,
scan_image_mime = false,
default_port = 5954,
timeout = 15.0,
log_clean = false,
retransmits = 2,
cache_expire = 7200, -- expire redis in 2h
message = '${SCANNER}: Oletools threat message found: "${VIRUS}"',
detection_category = "office macro",
default_score = 1,
action = false,
extended = false,
}
oletools_conf = lua_util.override_defaults(oletools_conf, opts)
if not oletools_conf.prefix then
oletools_conf.prefix = 'rs_' .. oletools_conf.name .. '_'
end
if not oletools_conf.log_prefix then
if oletools_conf.name:lower() == oletools_conf.type:lower() then
oletools_conf.log_prefix = oletools_conf.name
else
oletools_conf.log_prefix = oletools_conf.name .. ' (' .. oletools_conf.type .. ')'
end
end
if not oletools_conf.servers then
rspamd_logger.errx(rspamd_config, 'no servers defined')
return nil
end
oletools_conf.upstreams = upstream_list.create(rspamd_config,
oletools_conf.servers,
oletools_conf.default_port)
if oletools_conf.upstreams then
lua_util.add_debug_alias('antivirus', oletools_conf.module_name)
return oletools_conf
end
rspamd_logger.errx(rspamd_config, 'cannot parse servers %s',
oletools_conf.servers)
return nil
end
return {
type = {module_name,'office macro scanner', 'hash', 'scanner'},
description = 'oletools office macro scanner',
configure = oletools_config,
check = oletools_check,
name = module_name
}
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