suricata
detect-tls-ja3s-string.c
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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"
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  */
75 {
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 = DOC_URL DOC_VERSION "/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
85 
88 
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  */
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 
113  return -1;
114 
115  /* Check if JA3 is disabled */
116  if (!RunmodeIsUnittests() && Ja3IsDisabled("rule"))
117  return -1;
118 
119  return 0;
120 }
121 
122 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
123  const DetectEngineTransforms *transforms, Flow *f,
124  const uint8_t flow_flags, void *txv, const int list_id)
125 {
126  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
127  if (buffer->inspect == NULL) {
128  const SSLState *ssl_state = (SSLState *)f->alstate;
129 
130  if (ssl_state->server_connp.ja3_str == NULL ||
131  ssl_state->server_connp.ja3_str->data == NULL) {
132  return NULL;
133  }
134 
135  const uint32_t data_len = strlen(ssl_state->server_connp.ja3_str->data);
136  const uint8_t *data = (uint8_t *)ssl_state->server_connp.ja3_str->data;
137 
138  InspectionBufferSetup(buffer, data, data_len);
139  InspectionBufferApplyTransforms(buffer, transforms);
140  }
141 
142  return buffer;
143 }
144 
145 #ifdef UNITTESTS
147 #endif
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect.h:1439
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1179
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
SSLStateConnp server_connp
void DetectTlsJa3SStringRegister(void)
Registration function for keyword: ja3s.string.
char * data
Definition: util-ja3.h:30
int Ja3IsDisabled(const char *type)
Check if JA3 is disabled.
Definition: util-ja3.c:262
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
const char * name
Definition: detect.h:1193
Signature container.
Definition: detect.h:517
void DetectAppLayerMpmRegister2(const char *name, int direction, int priority, int(*PrefilterRegister)(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistery *mpm_reg, int list_id), InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register a MPM engine
main detection engine ctx
Definition: detect.h:756
SSLv[2.0|3.[0|1|2|3]] state structure.
void * alstate
Definition: flow.h:438
int DetectBufferTypeGetByName(const char *name)
#define str(s)
#define SIG_FLAG_TOCLIENT
Definition: detect.h:233
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1386
void DetectAppLayerInspectEngineRegister2(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr2 Callback2, InspectionBufferGetDataPtr GetData)
register inspect engine at start up time
int RunmodeIsUnittests(void)
Definition: suricata.c:265
int DetectEngineInspectBufferGeneric(DetectEngineCtx *de_ctx, DetectEngineThreadCtx *det_ctx, const DetectEngineAppInspectionEngine *engine, const Signature *s, Flow *f, uint8_t flags, void *alstate, void *txv, uint64_t tx_id)
Do the content inspection & validation for a signature.
const char * desc
Definition: detect.h:1195
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistery *mpm_reg, int list_id)
void InspectionBufferSetup(InspectionBuffer *buffer, const uint8_t *data, const uint32_t data_len)
setup the buffer with our initial data
void InspectionBufferApplyTransforms(InspectionBuffer *buffer, const DetectEngineTransforms *transforms)
#define SIGMATCH_NOOPT
Definition: detect.h:1362
const char * url
Definition: detect.h:1196
int DetectBufferSetActiveList(Signature *s, const int list)
const uint8_t * inspect
Definition: detect.h:338
#define DOC_URL
Definition: suricata.h:86
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
JA3Buffer * ja3_str
#define DOC_VERSION
Definition: suricata.h:91
uint16_t flags
Definition: detect.h:1187
Flow data structure.
Definition: flow.h:325
void(* RegisterTests)(void)
Definition: detect.h:1185