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  /* try to enable JA3 */
116  SSLEnableJA3();
117 
118  /* Check if JA3 is disabled */
119  if (!RunmodeIsUnittests() && Ja3IsDisabled("rule")) {
121  SCLogError(SC_WARN_JA3_DISABLED, "ja3(s) support is not enabled");
122  }
123  return -2;
124  }
125 
126  return 0;
127 }
128 
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(buffer, data, data_len);
146  InspectionBufferApplyTransforms(buffer, transforms);
147  }
148 
149  return buffer;
150 }
151 
152 #ifdef UNITTESTS
154 #endif
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect.h:1448
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1186
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:263
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
const char * name
Definition: detect.h:1200
Signature container.
Definition: detect.h:522
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:761
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:237
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1393
#define SCLogError(err_code,...)
Macro used to log ERROR messages.
Definition: util-debug.h:294
void DetectAppLayerInspectEngineRegister2(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr2 Callback2, InspectionBufferGetDataPtr GetData)
register inspect engine at start up time
void SSLEnableJA3(void)
if not explicitly disabled in config, enable ja3 support
bool SigMatchSilentErrorEnabled(const DetectEngineCtx *de_ctx, const enum DetectKeywordId id)
Definition: detect-parse.c:289
int RunmodeIsUnittests(void)
Definition: suricata.c:267
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:1202
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:1369
const char * url
Definition: detect.h:1203
int DetectBufferSetActiveList(Signature *s, const int list)
const uint8_t * inspect
Definition: detect.h:343
#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:1194
Flow data structure.
Definition: flow.h:325
void(* RegisterTests)(void)
Definition: detect.h:1192