From cbce2c78bd779daeafc541bd6f182941c14eeae0 Mon Sep 17 00:00:00 2001 From: Eric Leblond Date: Sun, 19 Nov 2017 20:21:08 +0100 Subject: [PATCH] detect-ftpdata: match on ftp-data operation This keyword mathes on ftp operation STOR and RETR. It will allow rules writer to select if the alert has to be on a put or a fetch operation. It is now possible to write a signature like: alert ftp-data any any -> any any (msg:"FTP data get firwmare"; ftdata_command:retr; sid:2; rev:1;) to alert when a file is retrieved from a FTP server. --- src/Makefile.am | 1 + src/detect-engine-register.h | 1 + src/detect-ftpbounce.c | 1 + src/detect-ftpdata.c | 278 +++++++++++++++++++++++++++++++++++ src/detect-ftpdata.h | 43 ++++++ 5 files changed, 324 insertions(+) create mode 100644 src/detect-ftpdata.c create mode 100644 src/detect-ftpdata.h diff --git a/src/Makefile.am b/src/Makefile.am index 4b89861f38..8158772b1e 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -243,6 +243,7 @@ detect-stream_size.c detect-stream_size.h \ detect-tag.c detect-tag.h \ detect-target.c detect-target.h \ detect-template.c detect-template.h \ +detect-ftpdata.c detect-ftpdata.h \ detect-template-buffer.c detect-template-buffer.h \ detect-threshold.c detect-threshold.h \ detect-tls.c detect-tls.h \ diff --git a/src/detect-engine-register.h b/src/detect-engine-register.h index d41e3f2785..09f88cc4b1 100644 --- a/src/detect-engine-register.h +++ b/src/detect-engine-register.h @@ -189,6 +189,7 @@ enum { DETECT_BASE64_DATA, DETECT_TEMPLATE, + DETECT_FTPDATA, DETECT_TARGET, DETECT_AL_TEMPLATE_BUFFER, diff --git a/src/detect-ftpbounce.c b/src/detect-ftpbounce.c index 64816f0c78..7ee29926b8 100644 --- a/src/detect-ftpbounce.c +++ b/src/detect-ftpbounce.c @@ -71,6 +71,7 @@ void DetectFtpbounceRegister(void) sigmatch_table[DETECT_FTPBOUNCE].Setup = DetectFtpbounceSetup; sigmatch_table[DETECT_FTPBOUNCE].AppLayerTxMatch = DetectFtpbounceALMatch; sigmatch_table[DETECT_FTPBOUNCE].RegisterTests = DetectFtpbounceRegisterTests; + sigmatch_table[DETECT_FTPBOUNCE].url = DOC_URL DOC_VERSION "/rules/ftp-keywords#ftpbounce"; sigmatch_table[DETECT_FTPBOUNCE].flags = SIGMATCH_NOOPT; g_ftp_request_list_id = DetectBufferTypeRegister("ftp_request"); diff --git a/src/detect-ftpdata.c b/src/detect-ftpdata.c new file mode 100644 index 0000000000..7c93c84c13 --- /dev/null +++ b/src/detect-ftpdata.c @@ -0,0 +1,278 @@ +/* Copyright (C) 2017 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 Eric Leblond + * + * Match on ftp command used to trigger a ftp data transfer + */ + +#include "suricata-common.h" +#include "util-unittest.h" + +#include "detect-parse.h" +#include "detect-engine.h" +#include "detect-engine-state.h" + +#include "app-layer-ftp.h" + +#include "detect-ftpdata.h" + +/** + * \brief Regex for parsing our keyword options + */ +#define PARSE_REGEX "^\\s*(stor|retr)\\s*$" +static pcre *parse_regex; +static pcre_extra *parse_regex_study; + +/* Prototypes of functions registered in DetectFtpdataRegister below */ +static int DetectFtpdataMatch(ThreadVars *, DetectEngineThreadCtx *, + Flow *, uint8_t, void *, void *, + const Signature *, const SigMatchCtx *); +static int DetectFtpdataSetup (DetectEngineCtx *, Signature *, const char *); +static void DetectFtpdataFree (void *); +static void DetectFtpdataRegisterTests (void); +static int DetectEngineInspectFtpdataGeneric(ThreadVars *tv, + DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx, + const Signature *s, const SigMatchData *smd, + Flow *f, uint8_t flags, void *alstate, + void *txv, uint64_t tx_id); +static int g_ftpdata_buffer_id = 0; + +/** + * \brief Registration function for ftpcommand: keyword + * + * This function is called once in the 'lifetime' of the engine. + */ +void DetectFtpdataRegister(void) { + /* keyword name: this is how the keyword is used in a rule */ + sigmatch_table[DETECT_FTPDATA].name = "ftpdata_command"; + /* description: listed in "suricata --list-keywords=all" */ + sigmatch_table[DETECT_FTPDATA].desc = "match FTP command triggering a FTP data channel"; + sigmatch_table[DETECT_FTPDATA].url = DOC_URL DOC_VERSION "/rules/ftp-keywords#ftpdata_command"; + sigmatch_table[DETECT_FTPDATA].AppLayerTxMatch = DetectFtpdataMatch; + /* setup function is called during signature parsing, when the ftpcommand + * keyword is encountered in the rule */ + sigmatch_table[DETECT_FTPDATA].Setup = DetectFtpdataSetup; + /* free function is called when the detect engine is freed. Normally at + * shutdown, but also during rule reloads. */ + sigmatch_table[DETECT_FTPDATA].Free = DetectFtpdataFree; + /* registers unittests into the system */ + sigmatch_table[DETECT_FTPDATA].RegisterTests = DetectFtpdataRegisterTests; + + DetectAppLayerInspectEngineRegister("ftpdata_command", + ALPROTO_FTPDATA, SIG_FLAG_TOSERVER, 0, + DetectEngineInspectFtpdataGeneric); + + DetectAppLayerInspectEngineRegister("ftpdata_command", + ALPROTO_FTPDATA, SIG_FLAG_TOCLIENT, 0, + DetectEngineInspectFtpdataGeneric); + g_ftpdata_buffer_id = DetectBufferTypeGetByName("ftpdata_command"); + + /* set up the PCRE for keyword parsing */ + DetectSetupParseRegexes(PARSE_REGEX, &parse_regex, &parse_regex_study); +} + +static int DetectEngineInspectFtpdataGeneric(ThreadVars *tv, + DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx, + const Signature *s, const SigMatchData *smd, + Flow *f, uint8_t flags, void *alstate, + void *txv, uint64_t tx_id) +{ + return DetectEngineInspectGenericList(tv, de_ctx, det_ctx, s, smd, + f, flags, alstate, txv, tx_id); +} + +/** + * \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 + * \retval 0 no match + * \retval 1 match + */ +static int DetectFtpdataMatch(ThreadVars *t, DetectEngineThreadCtx *det_ctx, + Flow *f, uint8_t flags, + void *state, void *txv, + const Signature *s, const SigMatchCtx *m) +{ + const DetectFtpdataData *ftpcommandd = (const DetectFtpdataData *) m; + const FtpDataState *ftp_state = (const FtpDataState *)state; + + if (ftp_state == NULL) + return 0; + + if (ftpcommandd->command == ftp_state->command) { + /* Only match if the flow is in the good direction */ + if ((flags & STREAM_TOSERVER) && (ftpcommandd->command == FTP_COMMAND_RETR)) { + return 0; + } else if ((flags & STREAM_TOCLIENT) && (ftpcommandd->command == FTP_COMMAND_STOR)) { + return 0; + } + return 1; + } + + return 0; +} + +/** + * \brief This function is used to parse ftpcommand options passed via ftpcommand: keyword + * + * \param ftpcommandstr Pointer to the user provided ftpcommand options + * + * \retval ftpcommandd pointer to DetectFtpdataData on success + * \retval NULL on failure + */ +static DetectFtpdataData *DetectFtpdataParse(const char *ftpcommandstr) +{ + DetectFtpdataData *ftpcommandd = NULL; + char arg1[5] = ""; +#define MAX_SUBSTRINGS 30 + int ret = 0, res = 0; + int ov[MAX_SUBSTRINGS]; + + ret = pcre_exec(parse_regex, parse_regex_study, + ftpcommandstr, strlen(ftpcommandstr), + 0, 0, ov, MAX_SUBSTRINGS); + if (ret != 2) { + SCLogError(SC_ERR_PCRE_MATCH, "parse error, ret %" PRId32 "", ret); + goto error; + } + + res = pcre_copy_substring((char *) ftpcommandstr, ov, MAX_SUBSTRINGS, 1, arg1, sizeof(arg1)); + if (res < 0) { + SCLogError(SC_ERR_PCRE_GET_SUBSTRING, "pcre_copy_substring failed"); + goto error; + } + SCLogDebug("Arg1 \"%s\"", arg1); + + ftpcommandd = SCMalloc(sizeof (DetectFtpdataData)); + if (unlikely(ftpcommandd == NULL)) + goto error; + if (!strcmp(arg1, "stor")) { + ftpcommandd->command = FTP_COMMAND_STOR; + } else if (!strcmp(arg1, "retr")) { + ftpcommandd->command = FTP_COMMAND_RETR; + } else { + SCLogError(SC_ERR_NOT_SUPPORTED, "Invalid command value"); + goto error; + } + + + return ftpcommandd; + +error: + if (ftpcommandd) + SCFree(ftpcommandd); + return NULL; +} + +/** + * \brief parse the options from the 'ftpcommand' keyword in the rule into + * the Signature data structure. + * + * \param de_ctx pointer to the Detection Engine Context + * \param s pointer to the Current Signature + * \param ftpcommandstr pointer to the user provided ftpcommand options + * + * \retval 0 on Success + * \retval -1 on Failure + */ +static int DetectFtpdataSetup(DetectEngineCtx *de_ctx, Signature *s, const char *ftpcommandstr) +{ + DetectFtpdataData *ftpcommandd = NULL; + SigMatch *sm = NULL; + + if (DetectSignatureSetAppProto(s, ALPROTO_FTPDATA) != 0) + return -1; + + ftpcommandd = DetectFtpdataParse(ftpcommandstr); + if (ftpcommandd == NULL) + goto error; + + sm = SigMatchAlloc(); + if (sm == NULL) + goto error; + + sm->type = DETECT_FTPDATA; + sm->ctx = (void *)ftpcommandd; + + s->flags |= SIG_FLAG_STATE_MATCH; + SigMatchAppendSMToList(s, sm, g_ftpdata_buffer_id); + + return 0; + +error: + if (ftpcommandd != NULL) + DetectFtpdataFree(ftpcommandd); + if (sm != NULL) + SCFree(sm); + return -1; +} + +/** + * \brief this function will free memory associated with DetectFtpdataData + * + * \param ptr pointer to DetectFtpdataData + */ +static void DetectFtpdataFree(void *ptr) { + DetectFtpdataData *ftpcommandd = (DetectFtpdataData *)ptr; + + /* do more specific cleanup here, if needed */ + + SCFree(ftpcommandd); +} + +#if UNITTESTS + +static int DetectFtpdataParseTest01(void) +{ + DetectFtpdataData *ftpcommandd = DetectFtpdataParse("stor"); + FAIL_IF_NULL(ftpcommandd); + FAIL_IF(!(ftpcommandd->command == FTP_COMMAND_STOR)); + DetectFtpdataFree(ftpcommandd); + PASS; +} + +static int DetectFtpdataSignatureTest01(void) +{ + DetectEngineCtx *de_ctx = DetectEngineCtxInit(); + FAIL_IF_NULL(de_ctx); + + Signature *sig = DetectEngineAppendSig(de_ctx, "alert ip any any -> any any (ftpdata_command:stor; sid:1; rev:1;)"); + FAIL_IF_NULL(sig); + + DetectEngineCtxFree(de_ctx); + PASS; +} + +#endif /* UNITTESTS */ + +/** + * \brief this function registers unit tests for DetectFtpdata + */ +void DetectFtpdataRegisterTests(void) { +#ifdef UNITTESTS + UtRegisterTest("DetectFtpdataParseTest01", DetectFtpdataParseTest01); + UtRegisterTest("DetectFtpdataSignatureTest01", + DetectFtpdataSignatureTest01); +#endif /* UNITTESTS */ +} diff --git a/src/detect-ftpdata.h b/src/detect-ftpdata.h new file mode 100644 index 0000000000..0f03ee1c97 --- /dev/null +++ b/src/detect-ftpdata.h @@ -0,0 +1,43 @@ +/* Copyright (C) 2017 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 Eric Leblond + */ + +#ifndef __DETECT_FTPDATA_H__ +#define __DETECT_FTPDATA_H__ + +#include "detect-engine.h" +#include "app-layer-ftp.h" + +/** Per keyword data. This is set up by the DetectFtpcommandSetup() function. + * Each signature will have an instance of DetectFtpcommandData per occurence + * of the keyword. + * The structure should be considered static/readonly after initialization. + */ +typedef struct DetectFtpdataData_ { + FtpRequestCommand command; +} DetectFtpdataData; + +/** \brief registers the keyword into the engine. Called from + * detect.c::SigTableSetup() */ +void DetectFtpdataRegister(void); + +#endif /* __DETECT_FTPDATA_H__ */