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-rw-r--r--src/detect-tls-ja3s-hash.c225
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diff --git a/src/detect-tls-ja3s-hash.c b/src/detect-tls-ja3s-hash.c
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+/* Copyright (C) 2019 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 Mats Klepsland <mats.klepsland@gmail.com>
+ *
+ * Implements support for ja3s.hash keyword.
+ */
+
+#include "suricata-common.h"
+#include "threads.h"
+#include "decode.h"
+#include "detect.h"
+
+#include "detect-parse.h"
+#include "detect-engine.h"
+#include "detect-engine-mpm.h"
+#include "detect-engine-prefilter.h"
+#include "detect-content.h"
+#include "detect-pcre.h"
+#include "detect-tls-ja3s-hash.h"
+
+#include "flow.h"
+#include "flow-util.h"
+#include "flow-var.h"
+
+#include "conf.h"
+#include "conf-yaml-loader.h"
+
+#include "util-debug.h"
+#include "util-spm.h"
+#include "util-print.h"
+#include "util-ja3.h"
+
+#include "stream-tcp.h"
+
+#include "app-layer.h"
+#include "app-layer-ssl.h"
+
+#include "util-unittest.h"
+#include "util-unittest-helper.h"
+
+static int DetectTlsJa3SHashSetup(DetectEngineCtx *, Signature *, const char *);
+static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
+ const DetectEngineTransforms *transforms,
+ Flow *f, const uint8_t flow_flags,
+ void *txv, const int list_id);
+static void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
+ Signature *s);
+static bool DetectTlsJa3SHashValidateCallback(const Signature *s,
+ const char **sigerror);
+static int g_tls_ja3s_hash_buffer_id = 0;
+
+/**
+ * \brief Registration function for keyword: ja3s.hash
+ */
+void DetectTlsJa3SHashRegister(void)
+{
+ sigmatch_table[DETECT_AL_TLS_JA3S_HASH].name = "ja3s.hash";
+ sigmatch_table[DETECT_AL_TLS_JA3S_HASH].desc = "sticky buffer to match the JA3S hash buffer";
+ sigmatch_table[DETECT_AL_TLS_JA3S_HASH].url = "/rules/ja3-keywords.html#ja3s-hash";
+ sigmatch_table[DETECT_AL_TLS_JA3S_HASH].Setup = DetectTlsJa3SHashSetup;
+ sigmatch_table[DETECT_AL_TLS_JA3S_HASH].flags |= SIGMATCH_NOOPT;
+ sigmatch_table[DETECT_AL_TLS_JA3S_HASH].flags |= SIGMATCH_INFO_STICKY_BUFFER;
+
+ DetectAppLayerInspectEngineRegister2("ja3s.hash", ALPROTO_TLS, SIG_FLAG_TOCLIENT, 0,
+ DetectEngineInspectBufferGeneric, GetData);
+
+ DetectAppLayerMpmRegister2("ja3s.hash", SIG_FLAG_TOCLIENT, 2,
+ PrefilterGenericMpmRegister, GetData, ALPROTO_TLS, 0);
+
+ DetectAppLayerMpmRegister2("ja3s.hash", SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,
+ Ja3DetectGetHash, ALPROTO_QUIC, 1);
+
+ DetectAppLayerInspectEngineRegister2("ja3s.hash", ALPROTO_QUIC, SIG_FLAG_TOCLIENT, 1,
+ DetectEngineInspectBufferGeneric, Ja3DetectGetHash);
+
+ DetectBufferTypeSetDescriptionByName("ja3s.hash", "TLS JA3S hash");
+
+ DetectBufferTypeRegisterSetupCallback("ja3s.hash",
+ DetectTlsJa3SHashSetupCallback);
+
+ DetectBufferTypeRegisterValidateCallback("ja3s.hash",
+ DetectTlsJa3SHashValidateCallback);
+
+ g_tls_ja3s_hash_buffer_id = DetectBufferTypeGetByName("ja3s.hash");
+}
+
+/**
+ * \brief this function setup the ja3s.hash modifier keyword used in the rule
+ *
+ * \param de_ctx Pointer to the Detection Engine Context
+ * \param s Pointer to the Signature to which the current keyword belongs
+ * \param str Should hold an empty string always
+ *
+ * \retval 0 On success
+ * \retval -1 On failure
+ */
+static int DetectTlsJa3SHashSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
+{
+ if (DetectBufferSetActiveList(de_ctx, s, g_tls_ja3s_hash_buffer_id) < 0)
+ return -1;
+
+ if (s->alproto != ALPROTO_UNKNOWN && s->alproto != ALPROTO_TLS && s->alproto != ALPROTO_QUIC) {
+ SCLogError("rule contains conflicting protocols.");
+ return -1;
+ }
+
+ /* try to enable JA3 */
+ SSLEnableJA3();
+
+ /* Check if JA3 is disabled */
+ if (!RunmodeIsUnittests() && Ja3IsDisabled("rule")) {
+ if (!SigMatchSilentErrorEnabled(de_ctx, DETECT_AL_TLS_JA3S_HASH)) {
+ SCLogError("ja3(s) support is not enabled");
+ }
+ return -2;
+ }
+ s->init_data->init_flags |= SIG_FLAG_INIT_JA3;
+
+ return 0;
+}
+
+static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
+ const DetectEngineTransforms *transforms, Flow *f,
+ const uint8_t flow_flags, void *txv, const int list_id)
+{
+ InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
+ if (buffer->inspect == NULL) {
+ const SSLState *ssl_state = (SSLState *)f->alstate;
+
+ if (ssl_state->server_connp.ja3_hash == NULL) {
+ return NULL;
+ }
+
+ const uint32_t data_len = strlen(ssl_state->server_connp.ja3_hash);
+ const uint8_t *data = (uint8_t *)ssl_state->server_connp.ja3_hash;
+
+ InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
+ InspectionBufferApplyTransforms(buffer, transforms);
+ }
+
+ return buffer;
+}
+
+static bool DetectTlsJa3SHashValidateCallback(const Signature *s,
+ const char **sigerror)
+{
+ for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
+ if (s->init_data->buffers[x].id != (uint32_t)g_tls_ja3s_hash_buffer_id)
+ continue;
+ const SigMatch *sm = s->init_data->buffers[x].head;
+ for (; sm != NULL; sm = sm->next) {
+ if (sm->type != DETECT_CONTENT)
+ continue;
+
+ const DetectContentData *cd = (DetectContentData *)sm->ctx;
+
+ if (cd->flags & DETECT_CONTENT_NOCASE) {
+ *sigerror = "ja3s.hash should not be used together with "
+ "nocase, since the rule is automatically "
+ "lowercased anyway which makes nocase redundant.";
+ SCLogWarning("rule %u: %s", s->id, *sigerror);
+ }
+
+ if (cd->content_len == SC_MD5_HEX_LEN)
+ return true;
+
+ *sigerror = "Invalid length of the specified JA3S hash (should "
+ "be 32 characters long). This rule will therefore "
+ "never match.";
+ SCLogError("rule %u: %s", s->id, *sigerror);
+ return false;
+ }
+ }
+ return true;
+}
+
+static void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
+ Signature *s)
+{
+ for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
+ if (s->init_data->buffers[x].id != (uint32_t)g_tls_ja3s_hash_buffer_id)
+ continue;
+ SigMatch *sm = s->init_data->buffers[x].head;
+ for (; sm != NULL; sm = sm->next) {
+ if (sm->type != DETECT_CONTENT)
+ continue;
+
+ DetectContentData *cd = (DetectContentData *)sm->ctx;
+
+ bool changed = false;
+ uint32_t u;
+ for (u = 0; u < cd->content_len; u++) {
+ if (isupper(cd->content[u])) {
+ cd->content[u] = u8_tolower(cd->content[u]);
+ changed = true;
+ }
+ }
+
+ /* recreate the context if changes were made */
+ if (changed) {
+ SpmDestroyCtx(cd->spm_ctx);
+ cd->spm_ctx =
+ SpmInitCtx(cd->content, cd->content_len, 1, de_ctx->spm_global_thread_ctx);
+ }
+ }
+ }
+}
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