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/* Copyright (C) 2007-2010 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Pablo Rincon <pablo.rincon.crespo@gmail.com>
*
* ftpbounce keyword, part of the detection engine.
*/
#include "suricata-common.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-state.h"
#include "detect-content.h"
#include "detect-engine-build.h"
#include "app-layer.h"
#include "app-layer-parser.h"
#include "app-layer-ftp.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "util-debug.h"
#include "flow.h"
#include "flow-var.h"
#include "flow-util.h"
#include "threads.h"
#include "detect-ftpbounce.h"
#include "stream-tcp.h"
#include "util-byte.h"
static int DetectFtpbounceALMatch(DetectEngineThreadCtx *,
Flow *, uint8_t, void *, void *,
const Signature *, const SigMatchCtx *);
static int DetectFtpbounceSetup(DetectEngineCtx *, Signature *, const char *);
static int g_ftp_request_list_id = 0;
/**
* \brief Registration function for ftpbounce: keyword
* \todo add support for no_stream and stream_only
*/
void DetectFtpbounceRegister(void)
{
sigmatch_table[DETECT_FTPBOUNCE].name = "ftpbounce";
sigmatch_table[DETECT_FTPBOUNCE].desc = "detect FTP bounce attacks";
sigmatch_table[DETECT_FTPBOUNCE].Setup = DetectFtpbounceSetup;
sigmatch_table[DETECT_FTPBOUNCE].AppLayerTxMatch = DetectFtpbounceALMatch;
sigmatch_table[DETECT_FTPBOUNCE].url = "/rules/ftp-keywords.html#ftpbounce";
sigmatch_table[DETECT_FTPBOUNCE].flags = SIGMATCH_NOOPT;
g_ftp_request_list_id = DetectBufferTypeRegister("ftp_request");
DetectAppLayerInspectEngineRegister2(
"ftp_request", ALPROTO_FTP, SIG_FLAG_TOSERVER, 0, DetectEngineInspectGenericList, NULL);
}
/**
* \brief This function is used to match ftpbounce attacks
*
* \param payload Payload of the PORT command
* \param payload_len Length of the payload
* \param ip_orig IP source to check the ftpbounce condition
* \param offset offset to the arguments of the PORT command
*
* \retval 1 if ftpbounce detected, 0 if not
*/
static int DetectFtpbounceMatchArgs(
uint8_t *payload, uint32_t payload_len, uint32_t ip_orig, uint32_t offset)
{
SCEnter();
SCLogDebug("Checking ftpbounce condition");
char *c = NULL;
uint32_t i = 0;
int octet = 0;
int octet_ascii_len = 0;
int noctet = 0;
uint32_t ip = 0;
/* PrintRawDataFp(stdout, payload, payload_len); */
if (payload_len < 7) {
/* we need at least a different ip address
* in the format 1,2,3,4,x,y where x,y is the port
* in two byte representation so let's look at
* least for the IP octets in comma separated */
return 0;
}
if (offset + 7 >= payload_len)
return 0;
c =(char*) payload;
if (c == NULL) {
SCLogDebug("No payload to check");
return 0;
}
i = offset;
/* Search for the first IP octect(Skips "PORT ") */
while (i < payload_len && !isdigit((unsigned char)c[i])) i++;
for (;i < payload_len && octet_ascii_len < 4 ;i++) {
if (isdigit((unsigned char)c[i])) {
octet =(c[i] - '0') + octet * 10;
octet_ascii_len++;
} else {
if (octet > 256) {
SCLogDebug("Octet not in ip format");
return 0;
}
if (isspace((unsigned char)c[i]))
while (i < payload_len && isspace((unsigned char)c[i]) ) i++;
if (i < payload_len && c[i] == ',') { /* we have an octet */
noctet++;
octet_ascii_len = 0;
ip =(ip << 8) + octet;
octet = 0;
} else {
SCLogDebug("Unrecognized character '%c'", c[i]);
return 0;
}
if (noctet == 4) {
/* Different IP than src, ftp bounce scan */
ip = SCNtohl(ip);
if (ip != ip_orig) {
SCLogDebug("Different ip, so Matched ip:%d <-> ip_orig:%d",
ip, ip_orig);
return 1;
}
SCLogDebug("Same ip, so no match here");
return 0;
}
}
}
SCLogDebug("No match");
return 0;
}
/**
* \brief This function is used to check matches from the FTP App Layer Parser
*
* \param t pointer to thread vars
* \param det_ctx pointer to the pattern matcher thread
* \param p pointer to the current packet
* \param m pointer to the sigmatch but we don't use it since ftpbounce
* has no options
* \retval 0 no match
* \retval 1 match
*/
static int DetectFtpbounceALMatch(DetectEngineThreadCtx *det_ctx,
Flow *f, uint8_t flags,
void *state, void *txv,
const Signature *s, const SigMatchCtx *m)
{
SCEnter();
FtpState *ftp_state = (FtpState *)state;
if (ftp_state == NULL) {
SCLogDebug("no ftp state, no match");
SCReturnInt(0);
}
int ret = 0;
if (ftp_state->command == FTP_COMMAND_PORT) {
ret = DetectFtpbounceMatchArgs(ftp_state->port_line,
ftp_state->port_line_len, f->src.address.address_un_data32[0],
ftp_state->arg_offset);
}
SCReturnInt(ret);
}
/**
* \brief this function is used to add the parsed ftpbounce
*
* \param de_ctx pointer to the Detection Engine Context
* \param s pointer to the Current Signature
* \param m pointer to the Current SigMatch
* \param ftpbouncestr pointer to the user provided ftpbounce options
* currently there are no options.
*
* \retval 0 on Success
* \retval -1 on Failure
*/
int DetectFtpbounceSetup(DetectEngineCtx *de_ctx, Signature *s, const char *ftpbouncestr)
{
SCEnter();
SigMatch *sm = NULL;
if (DetectSignatureSetAppProto(s, ALPROTO_FTP) != 0)
return -1;
sm = SigMatchAlloc();
if (sm == NULL) {
return -1;
}
sm->type = DETECT_FTPBOUNCE;
/* We don't need to allocate any data for ftpbounce here.
*
* TODO: As a suggestion, maybe we can add a flag in the flow
* to set the stream as "bounce detected" for fast Match.
* When you do a ftp bounce attack you usually use the same
* communication control stream to "setup" various destinations
* without breaking the connection, so I guess we can make it a bit faster
* with a flow flag set lookup in the Match function.
*/
sm->ctx = NULL;
SigMatchAppendSMToList(s, sm, g_ftp_request_list_id);
SCReturnInt(0);
}
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