1 /* Copyright (C) 2019 Open Information Security Foundation
2 *
3 * You can copy, redistribute or modify this Program under the terms of
4 * the GNU General Public License version 2 as published by the Free
5 * Software Foundation.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * version 2 along with this program; if not, write to the Free Software
14 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15 * 02110-1301, USA.
16 */
17
18 /**
19 * \file
20 *
21 * \author Mats Klepsland <mats.klepsland@gmail.com>
22 *
23 * Implements support for ja3s.string keyword.
24 */
25
26 #include "suricata-common.h"
27 #include "threads.h"
28 #include "debug.h"
29 #include "decode.h"
30 #include "detect.h"
31
32 #include "detect-parse.h"
33 #include "detect-engine.h"
34 #include "detect-engine-mpm.h"
35 #include "detect-engine-prefilter.h"
36 #include "detect-content.h"
37 #include "detect-pcre.h"
38 #include "detect-tls-ja3s-string.h"
39
40 #include "flow.h"
41 #include "flow-util.h"
42 #include "flow-var.h"
43
44 #include "conf.h"
45 #include "conf-yaml-loader.h"
46
47 #include "util-debug.h"
48 #include "util-unittest.h"
49 #include "util-spm.h"
50 #include "util-print.h"
51 #include "util-ja3.h"
52
53 #include "stream-tcp.h"
54
55 #include "app-layer.h"
56 #include "app-layer-ssl.h"
57
58 #include "util-unittest.h"
59 #include "util-unittest-helper.h"
60
61 static int DetectTlsJa3SStringSetup(DetectEngineCtx *, Signature *, const char *);
62 #ifdef UNITTESTS
63 static void DetectTlsJa3SStringRegisterTests(void);
64 #endif
65 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
66 const DetectEngineTransforms *transforms,
67 Flow *f, const uint8_t flow_flags,
68 void *txv, const int list_id);
69 static int g_tls_ja3s_str_buffer_id = 0;
70
71 /**
72 * \brief Registration function for keyword: ja3s.string
73 */
DetectTlsJa3SStringRegister(void)74 void DetectTlsJa3SStringRegister(void)
75 {
76 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].name = "ja3s.string";
77 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].desc = "content modifier to match the JA3S string sticky buffer";
78 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].url = "/rules/ja3-keywords.html#ja3s-string";
79 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].Setup = DetectTlsJa3SStringSetup;
80 #ifdef UNITTESTS
81 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].RegisterTests = DetectTlsJa3SStringRegisterTests;
82 #endif
83 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].flags |= SIGMATCH_NOOPT;
84 sigmatch_table[DETECT_AL_TLS_JA3S_STRING].flags |= SIGMATCH_INFO_STICKY_BUFFER;
85
86 DetectAppLayerInspectEngineRegister2("ja3s.string", ALPROTO_TLS, SIG_FLAG_TOCLIENT, 0,
87 DetectEngineInspectBufferGeneric, GetData);
88
89 DetectAppLayerMpmRegister2("ja3s.string", SIG_FLAG_TOCLIENT, 2,
90 PrefilterGenericMpmRegister, GetData, ALPROTO_TLS, 0);
91
92 DetectBufferTypeSetDescriptionByName("ja3s.string", "TLS JA3S string");
93
94 g_tls_ja3s_str_buffer_id = DetectBufferTypeGetByName("ja3s.string");
95 }
96
97 /**
98 * \brief this function setup the ja3s.string modifier keyword used in the rule
99 *
100 * \param de_ctx Pointer to the Detection Engine Context
101 * \param s Pointer to the Signature to which the current keyword belongs
102 * \param str Should hold an empty string always
103 *
104 * \retval 0 On success
105 * \retval -1 On failure
106 */
DetectTlsJa3SStringSetup(DetectEngineCtx * de_ctx,Signature * s,const char * str)107 static int DetectTlsJa3SStringSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
108 {
109 if (DetectBufferSetActiveList(s, g_tls_ja3s_str_buffer_id) < 0)
110 return -1;
111
112 if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)
113 return -1;
114
115 /* try to enable JA3 */
116 SSLEnableJA3();
117
118 /* Check if JA3 is disabled */
119 if (!RunmodeIsUnittests() && Ja3IsDisabled("rule")) {
120 if (!SigMatchSilentErrorEnabled(de_ctx, DETECT_AL_TLS_JA3S_STRING)) {
121 SCLogError(SC_WARN_JA3_DISABLED, "ja3(s) support is not enabled");
122 }
123 return -2;
124 }
125
126 return 0;
127 }
128
GetData(DetectEngineThreadCtx * det_ctx,const DetectEngineTransforms * transforms,Flow * f,const uint8_t flow_flags,void * txv,const int list_id)129 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
130 const DetectEngineTransforms *transforms, Flow *f,
131 const uint8_t flow_flags, void *txv, const int list_id)
132 {
133 InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
134 if (buffer->inspect == NULL) {
135 const SSLState *ssl_state = (SSLState *)f->alstate;
136
137 if (ssl_state->server_connp.ja3_str == NULL ||
138 ssl_state->server_connp.ja3_str->data == NULL) {
139 return NULL;
140 }
141
142 const uint32_t data_len = strlen(ssl_state->server_connp.ja3_str->data);
143 const uint8_t *data = (uint8_t *)ssl_state->server_connp.ja3_str->data;
144
145 InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
146 InspectionBufferApplyTransforms(buffer, transforms);
147 }
148
149 return buffer;
150 }
151
152 #ifdef UNITTESTS
153 #include "tests/detect-tls-ja3s-string.c"
154 #endif
155