83 lines
2.7 KiB
C++
83 lines
2.7 KiB
C++
/*
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*
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* Copyright (c) 2011-2016 The University of Waikato, Hamilton, New Zealand.
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* All rights reserved.
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*
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* This file is part of libprotoident.
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*
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* This code has been developed by the University of Waikato WAND
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* research group. For further information please see http://www.wand.net.nz/
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*
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* libprotoident is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* libprotoident is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#include <string.h>
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#include "libprotoident.h"
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#include "proto_manager.h"
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#include "proto_common.h"
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/* Strange flows that seem to be related to users running the Baidu browser.
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* The flow will connect to a Baidu server on port 80, send no data, then
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* start sending FINs. After about 6 FINs, the client will then send a one
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* byte packet with a sequence number matching the original SYN (which is
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* of course completely invalid). At this point, the server usually terminates
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* the connection.
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*
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* Confirmed as being associated with Baidu browser after observing this
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* exact traffic after installing the browser.
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*
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* Not sure what the purpose of this is, or how the browser manages to send
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* invalid TCP traffic but it is the root cause behind a lot of non-HTTP
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* flows on TCP port 80.
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*/
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static inline bool match_badbaidu(lpi_data_t *data, lpi_module_t *mod UNUSED) {
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/* Only seen on port 80 */
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if (data->client_port != 80 && data->server_port != 80)
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return false;
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/* Packet is one byte; the byte itself is 0x00. The other end
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* does not send any payload.
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*/
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if (data->payload_len[0] == 0 && data->payload_len[1] == 1) {
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if (MATCH(data->payload[1], 0x00, 0x00, 0x00, 0x00))
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return true;
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}
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if (data->payload_len[1] == 0 && data->payload_len[0] == 1) {
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if (MATCH(data->payload[0], 0x00, 0x00, 0x00, 0x00))
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return true;
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}
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return false;
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}
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static lpi_module_t lpi_badbaidu = {
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LPI_PROTO_BADBAIDU,
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LPI_CATEGORY_MALWARE,
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"BadBaidu",
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100,
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match_badbaidu
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};
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void register_badbaidu(LPIModuleMap *mod_map) {
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register_protocol(&lpi_badbaidu, mod_map);
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}
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