suricata
detect-tls-ja3s-hash.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.hash keyword.
24  */
25 
26 #include "suricata-common.h"
27 #include "threads.h"
28 #include "decode.h"
29 #include "detect.h"
30 
31 #include "detect-parse.h"
32 #include "detect-engine.h"
33 #include "detect-engine-mpm.h"
35 #include "detect-content.h"
36 #include "detect-pcre.h"
37 #include "detect-tls-ja3s-hash.h"
38 
39 #include "flow.h"
40 #include "flow-util.h"
41 #include "flow-var.h"
42 
43 #include "conf.h"
44 #include "conf-yaml-loader.h"
45 
46 #include "util-debug.h"
47 #include "util-spm.h"
48 #include "util-print.h"
49 #include "util-ja3.h"
50 
51 #include "stream-tcp.h"
52 
53 #include "app-layer.h"
54 #include "app-layer-ssl.h"
55 
56 #include "util-unittest.h"
57 #include "util-unittest-helper.h"
58 
59 static int DetectTlsJa3SHashSetup(DetectEngineCtx *, Signature *, const char *);
60 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
61  const DetectEngineTransforms *transforms,
62  Flow *f, const uint8_t flow_flags,
63  void *txv, const int list_id);
64 static void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
65  Signature *s);
66 static bool DetectTlsJa3SHashValidateCallback(const Signature *s,
67  const char **sigerror);
68 static int g_tls_ja3s_hash_buffer_id = 0;
69 
70 /**
71  * \brief Registration function for keyword: ja3s.hash
72  */
74 {
76  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].desc = "sticky buffer to match the JA3S hash buffer";
77  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].url = "/rules/ja3-keywords.html#ja3s-hash";
78  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].Setup = DetectTlsJa3SHashSetup;
81 
84 
86  GetData, ALPROTO_TLS, 0);
87 
90 
93 
94  DetectBufferTypeSetDescriptionByName("ja3s.hash", "TLS JA3S hash");
95 
97  DetectTlsJa3SHashSetupCallback);
98 
100  DetectTlsJa3SHashValidateCallback);
101 
102  g_tls_ja3s_hash_buffer_id = DetectBufferTypeGetByName("ja3s.hash");
103 }
104 
105 /**
106  * \brief this function setup the ja3s.hash modifier keyword used in the rule
107  *
108  * \param de_ctx Pointer to the Detection Engine Context
109  * \param s Pointer to the Signature to which the current keyword belongs
110  * \param str Should hold an empty string always
111  *
112  * \retval 0 On success
113  * \retval -1 On failure
114  */
115 static int DetectTlsJa3SHashSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
116 {
117  if (DetectBufferSetActiveList(de_ctx, s, g_tls_ja3s_hash_buffer_id) < 0)
118  return -1;
119 
120  if (s->alproto != ALPROTO_UNKNOWN && s->alproto != ALPROTO_TLS && s->alproto != ALPROTO_QUIC) {
121  SCLogError("rule contains conflicting protocols.");
122  return -1;
123  }
124 
125  /* try to enable JA3 */
126  SSLEnableJA3();
127 
128  /* Check if JA3 is disabled */
129  if (!RunmodeIsUnittests() && Ja3IsDisabled("rule")) {
131  SCLogError("ja3(s) support is not enabled");
132  }
133  return -2;
134  }
136 
137  return 0;
138 }
139 
140 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
141  const DetectEngineTransforms *transforms, Flow *f,
142  const uint8_t flow_flags, void *txv, const int list_id)
143 {
144  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
145  if (buffer->inspect == NULL) {
146  const SSLState *ssl_state = (SSLState *)f->alstate;
147 
148  if (ssl_state->server_connp.ja3_hash == NULL) {
149  return NULL;
150  }
151 
152  const uint32_t data_len = strlen(ssl_state->server_connp.ja3_hash);
153  const uint8_t *data = (uint8_t *)ssl_state->server_connp.ja3_hash;
154 
155  InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
156  InspectionBufferApplyTransforms(buffer, transforms);
157  }
158 
159  return buffer;
160 }
161 
162 static bool DetectTlsJa3SHashValidateCallback(const Signature *s,
163  const char **sigerror)
164 {
165  for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
166  if (s->init_data->buffers[x].id != (uint32_t)g_tls_ja3s_hash_buffer_id)
167  continue;
168  const SigMatch *sm = s->init_data->buffers[x].head;
169  for (; sm != NULL; sm = sm->next) {
170  if (sm->type != DETECT_CONTENT)
171  continue;
172 
173  const DetectContentData *cd = (DetectContentData *)sm->ctx;
174 
175  if (cd->flags & DETECT_CONTENT_NOCASE) {
176  *sigerror = "ja3s.hash should not be used together with "
177  "nocase, since the rule is automatically "
178  "lowercased anyway which makes nocase redundant.";
179  SCLogWarning("rule %u: %s", s->id, *sigerror);
180  }
181 
182  if (cd->content_len == SC_MD5_HEX_LEN)
183  return true;
184 
185  *sigerror = "Invalid length of the specified JA3S hash (should "
186  "be 32 characters long). This rule will therefore "
187  "never match.";
188  SCLogError("rule %u: %s", s->id, *sigerror);
189  return false;
190  }
191  }
192  return true;
193 }
194 
195 static void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
196  Signature *s)
197 {
198  for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
199  if (s->init_data->buffers[x].id != (uint32_t)g_tls_ja3s_hash_buffer_id)
200  continue;
201  SigMatch *sm = s->init_data->buffers[x].head;
202  for (; sm != NULL; sm = sm->next) {
203  if (sm->type != DETECT_CONTENT)
204  continue;
205 
207 
208  bool changed = false;
209  uint32_t u;
210  for (u = 0; u < cd->content_len; u++) {
211  if (isupper(cd->content[u])) {
212  cd->content[u] = u8_tolower(cd->content[u]);
213  changed = true;
214  }
215  }
216 
217  /* recreate the context if changes were made */
218  if (changed) {
219  SpmDestroyCtx(cd->spm_ctx);
220  cd->spm_ctx =
222  }
223  }
224  }
225 }
DETECT_CONTENT_NOCASE
#define DETECT_CONTENT_NOCASE
Definition: detect-content.h:29
Ja3DetectGetHash
InspectionBuffer * Ja3DetectGetHash(DetectEngineThreadCtx *det_ctx, const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv, const int list_id)
Definition: util-ja3.c:259
SigTableElmt_::url
const char * url
Definition: detect.h:1295
SignatureInitDataBuffer_::head
SigMatch * head
Definition: detect.h:526
SSLState_
SSLv[2.0|3.[0|1|2|3]] state structure.
Definition: app-layer-ssl.h:284
detect-content.h
detect-engine.h
SIGMATCH_INFO_STICKY_BUFFER
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1496
SigTableElmt_::desc
const char * desc
Definition: detect.h:1294
DetectTlsJa3SHashRegister
void DetectTlsJa3SHashRegister(void)
Registration function for keyword: ja3s.hash.
Definition: detect-tls-ja3s-hash.c:73
DetectEngineInspectBufferGeneric
uint8_t 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.
Definition: detect-engine.c:2169
flow-util.h
SIG_FLAG_INIT_JA3
#define SIG_FLAG_INIT_JA3
Definition: detect.h:292
SigTableElmt_::name
const char * name
Definition: detect.h:1292
stream-tcp.h
DetectEngineTransforms
Definition: detect.h:405
DETECT_CONTENT
@ DETECT_CONTENT
Definition: detect-engine-register.h:62
ALPROTO_TLS
@ ALPROTO_TLS
Definition: app-layer-protos.h:33
Signature_::alproto
AppProto alproto
Definition: detect.h:597
SSLState_::server_connp
SSLStateConnp server_connp
Definition: app-layer-ssl.h:303
ALPROTO_QUIC
@ ALPROTO_QUIC
Definition: app-layer-protos.h:51
DetectBufferSetActiveList
int DetectBufferSetActiveList(DetectEngineCtx *de_ctx, Signature *s, const int list)
Definition: detect-engine.c:1382
SSLStateConnp_::ja3_hash
char * ja3_hash
Definition: app-layer-ssl.h:268
InspectionBuffer
Definition: detect.h:370
threads.h
Flow_
Flow data structure.
Definition: flow.h:350
DetectBufferTypeRegisterSetupCallback
void DetectBufferTypeRegisterSetupCallback(const char *name, void(*SetupCallback)(const DetectEngineCtx *, Signature *))
Definition: detect-engine.c:1313
SigTableElmt_::flags
uint16_t flags
Definition: detect.h:1286
DetectEngineCtx_
main detection engine ctx
Definition: detect.h:835
u8_tolower
#define u8_tolower(c)
Definition: suricata-common.h:436
util-ja3.h
SignatureInitData_::init_flags
uint32_t init_flags
Definition: detect.h:544
DetectContentData_
Definition: detect-content.h:93
SIG_FLAG_TOCLIENT
#define SIG_FLAG_TOCLIENT
Definition: detect.h:263
SigTableElmt_::Setup
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1277
detect-pcre.h
detect-engine-prefilter.h
util-unittest.h
InspectionBufferGet
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
Definition: detect-engine.c:1526
util-unittest-helper.h
DetectBufferTypeGetByName
int DetectBufferTypeGetByName(const char *name)
Definition: detect-engine.c:1119
Ja3IsDisabled
int Ja3IsDisabled(const char *type)
Check if JA3 is disabled.
Definition: util-ja3.c:246
decode.h
util-debug.h
DetectBufferTypeRegisterValidateCallback
void DetectBufferTypeRegisterValidateCallback(const char *name, bool(*ValidateCallback)(const Signature *, const char **sigerror))
Definition: detect-engine.c:1331
de_ctx
DetectEngineCtx * de_ctx
Definition: fuzz_siginit.c:17
DetectEngineThreadCtx_
Definition: detect.h:1091
util-print.h
detect-engine-mpm.h
detect.h
SigMatch_::next
struct SigMatch_ * next
Definition: detect.h:350
DETECT_AL_TLS_JA3S_HASH
@ DETECT_AL_TLS_JA3S_HASH
Definition: detect-engine-register.h:247
PrefilterGenericMpmRegister
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistry *mpm_reg, int list_id)
Definition: detect-engine-prefilter.c:745
SCLogWarning
#define SCLogWarning(...)
Macro used to log WARNING messages.
Definition: util-debug.h:249
DetectAppLayerMpmRegister
void DetectAppLayerMpmRegister(const char *name, int direction, int priority, PrefilterRegisterFunc PrefilterRegister, InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register a MPM engine
Definition: detect-engine-mpm.c:89
SigMatch_::ctx
SigMatchCtx * ctx
Definition: detect.h:349
conf-yaml-loader.h
conf.h
DetectContentData_::flags
uint32_t flags
Definition: detect-content.h:104
SSLEnableJA3
void SSLEnableJA3(void)
if not explicitly disabled in config, enable ja3 support
Definition: app-layer-ssl.c:3090
Signature_::init_data
SignatureInitData * init_data
Definition: detect.h:661
RunmodeIsUnittests
int RunmodeIsUnittests(void)
Definition: suricata.c:252
SigMatchSilentErrorEnabled
bool SigMatchSilentErrorEnabled(const DetectEngineCtx *de_ctx, const enum DetectKeywordId id)
Definition: detect-parse.c:389
suricata-common.h
SigMatch_::type
uint16_t type
Definition: detect.h:347
InspectionBufferApplyTransforms
void InspectionBufferApplyTransforms(InspectionBuffer *buffer, const DetectEngineTransforms *transforms)
Definition: detect-engine.c:1725
sigmatch_table
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect-parse.c:127
util-spm.h
DetectContentData_::content
uint8_t * content
Definition: detect-content.h:94
DetectContentData_::spm_ctx
SpmCtx * spm_ctx
Definition: detect-content.h:111
SignatureInitData_::buffers
SignatureInitDataBuffer * buffers
Definition: detect.h:582
InspectionBuffer::inspect
const uint8_t * inspect
Definition: detect.h:371
str
#define str(s)
Definition: suricata-common.h:291
SCLogError
#define SCLogError(...)
Macro used to log ERROR messages.
Definition: util-debug.h:261
InspectionBufferSetup
void InspectionBufferSetup(DetectEngineThreadCtx *det_ctx, const int list_id, InspectionBuffer *buffer, const uint8_t *data, const uint32_t data_len)
setup the buffer with our initial data
Definition: detect-engine.c:1621
Flow_::alstate
void * alstate
Definition: flow.h:475
Signature_::id
uint32_t id
Definition: detect.h:627
detect-tls-ja3s-hash.h
detect-parse.h
SignatureInitDataBuffer_::id
uint32_t id
Definition: detect.h:519
Signature_
Signature container.
Definition: detect.h:592
SigMatch_
a single match condition for a signature
Definition: detect.h:346
ALPROTO_UNKNOWN
@ ALPROTO_UNKNOWN
Definition: app-layer-protos.h:29
DetectContentData_::content_len
uint16_t content_len
Definition: detect-content.h:95
SIGMATCH_NOOPT
#define SIGMATCH_NOOPT
Definition: detect.h:1472
DetectAppLayerInspectEngineRegister
void DetectAppLayerInspectEngineRegister(const char *name, AppProto alproto, uint32_t dir, int progress, InspectEngineFuncPtr Callback, InspectionBufferGetDataPtr GetData)
register inspect engine at start up time
Definition: detect-engine.c:216
DetectEngineCtx_::spm_global_thread_ctx
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition: detect.h:887
DetectBufferTypeSetDescriptionByName
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
Definition: detect-engine.c:1216
flow.h
SpmDestroyCtx
void SpmDestroyCtx(SpmCtx *ctx)
Definition: util-spm.c:183
SignatureInitData_::buffer_index
uint32_t buffer_index
Definition: detect.h:583
flow-var.h
SpmInitCtx
SpmCtx * SpmInitCtx(const uint8_t *needle, uint16_t needle_len, int nocase, SpmGlobalThreadCtx *global_thread_ctx)
Definition: util-spm.c:173
app-layer-ssl.h
app-layer.h