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.

diff --git a/src/Makefile.am b/src/Makefile.am
index 4b89861f38265a0bf56a10e382e452b669806402..8158772b1e262598ba94b8962c07121abe8a4b94 100644 (file)
--- 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 d41e3f2785c1724b5a17717caa56bfc10cc0a565..09f88cc4b1c93c3160341730cc5e6ca97d2a43be 100644 (file)
--- 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 64816f0c78750eb00ca472546266f8707b86b923..7ee29926b88076133e1ffb1ef1a96b56809030c0 100644 (file)
--- 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 (file)
index 0000000..7c93c84
--- /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 <eric@regit.org>
+ *
+ * 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 (file)
index 0000000..0f03ee1
--- /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 <eric@regit.org>
+ */
+
+#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__ */