1 files changed, 143 insertions, 0 deletions
diff --git a/src/detect-ssh-hassh-server-string.c b/src/detect-ssh-hassh-server-string.c
new file mode 100644
index 0000000..27b0e0c
--- /dev/null
+++ b/src/detect-ssh-hassh-server-string.c
@@ -0,0 +1,143 @@
+/* Copyright (C) 2007-2020 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 Vadym Malakhatko <v.malakhatko@sirinsoftware.com>
+ */
+
+#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-state.h"
+#include "detect-engine-prefilter.h"
+
+#include "flow.h"
+#include "flow-var.h"
+#include "flow-util.h"
+#include "stream-tcp.h"
+#include "util-debug.h"
+#include "util-unittest.h"
+#include "util-unittest-helper.h"
+
+#include "app-layer.h"
+#include "app-layer-parser.h"
+#include "app-layer-ssh.h"
+#include "detect-ssh-hassh-server-string.h"
+#include "rust.h"
+
+
+#define KEYWORD_NAME "ssh.hassh.server.string"
+#define KEYWORD_ALIAS "ssh-hassh-server-string"
+#define KEYWORD_DOC "ssh-keywords.html#ssh.hassh.server.string"
+#define BUFFER_NAME "ssh.hassh.server.string"
+#define BUFFER_DESC "Ssh Client Key Exchange methods For ssh Servers"
+static int g_ssh_hassh_server_string_buffer_id = 0;
+
+
+static InspectionBuffer *GetSshData(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Flow *_f,
+        const uint8_t flow_flags, void *txv, const int list_id)
+{
+    
+    SCEnter();
+
+    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
+
+    if (buffer->inspect == NULL) {
+        const uint8_t *hassh = NULL;
+        uint32_t b_len = 0;
+
+        if (rs_ssh_tx_get_hassh_string(txv, &hassh, &b_len, flow_flags) != 1)
+            return NULL;
+        if (hassh == NULL || b_len == 0) {
+            SCLogDebug("SSH hassh string is not set");
+            return NULL;
+        }
+
+        InspectionBufferSetup(det_ctx, list_id, buffer, hassh, b_len);
+        InspectionBufferApplyTransforms(buffer, transforms);
+    }
+
+    return buffer;
+}
+
+/**
+ * \brief this function setup the ssh.hassh.server.string 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
+ * \retval -2 on failure that should be silent after the first
+ */
+static int DetectSshHasshServerStringSetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)
+{
+    if (DetectBufferSetActiveList(de_ctx, s, g_ssh_hassh_server_string_buffer_id) < 0)
+        return -1;
+
+    if (DetectSignatureSetAppProto(s, ALPROTO_SSH) < 0)
+        return -1;
+     
+    /* try to enable Hassh */
+    rs_ssh_enable_hassh();
+
+    /* Check if Hassh is disabled */
+    if (!RunmodeIsUnittests() && !rs_ssh_hassh_is_enabled()) {
+        if (!SigMatchSilentErrorEnabled(de_ctx, DETECT_AL_SSH_HASSH_SERVER_STRING)) {
+            SCLogError("hassh support is not enabled");
+        }
+        return -2;
+    }
+
+    return 0;
+
+}
+
+/**
+ * \brief Registration function for hasshServer.string keyword.
+ */
+void DetectSshHasshServerStringRegister(void) 
+{
+    sigmatch_table[DETECT_AL_SSH_HASSH_SERVER_STRING].name = KEYWORD_NAME;
+    sigmatch_table[DETECT_AL_SSH_HASSH_SERVER_STRING].alias = KEYWORD_ALIAS;
+    sigmatch_table[DETECT_AL_SSH_HASSH_SERVER_STRING].desc = BUFFER_NAME " sticky buffer";
+    sigmatch_table[DETECT_AL_SSH_HASSH_SERVER_STRING].url = "/rules/" KEYWORD_DOC;
+    sigmatch_table[DETECT_AL_SSH_HASSH_SERVER_STRING].Setup = DetectSshHasshServerStringSetup;
+    sigmatch_table[DETECT_AL_SSH_HASSH_SERVER_STRING].flags |= SIGMATCH_INFO_STICKY_BUFFER | SIGMATCH_NOOPT;
+
+
+    DetectAppLayerMpmRegister2(BUFFER_NAME, SIG_FLAG_TOCLIENT, 2, 
+            PrefilterGenericMpmRegister, GetSshData,
+            ALPROTO_SSH, SshStateBannerDone);
+    DetectAppLayerInspectEngineRegister2(BUFFER_NAME, ALPROTO_SSH, 
+            SIG_FLAG_TOCLIENT, SshStateBannerDone, 
+            DetectEngineInspectBufferGeneric, GetSshData);
+
+    DetectBufferTypeSetDescriptionByName(BUFFER_NAME, BUFFER_DESC);
+
+    g_ssh_hassh_server_string_buffer_id = DetectBufferTypeGetByName(BUFFER_NAME);
+}