suricata
detect-tls-ja3s-hash.c
Go to the documentation of this file.
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 "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-hash.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 DetectTlsJa3SHashSetup(DetectEngineCtx *, Signature *, const char *);
62 #ifdef UNITTESTS
63 static void DetectTlsJa3SHashRegisterTests(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 void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
70  Signature *s);
71 static _Bool DetectTlsJa3SHashValidateCallback(const Signature *s,
72  const char **sigerror);
73 static int g_tls_ja3s_hash_buffer_id = 0;
74 
75 /**
76  * \brief Registration function for keyword: ja3s.hash
77  */
79 {
81  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].desc = "content modifier to match the JA3S hash sticky buffer";
82  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].url = DOC_URL DOC_VERSION "/rules/ja3-keywords.html#ja3s-hash";
83  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].Setup = DetectTlsJa3SHashSetup;
84 #ifdef UNITTESTS
85  sigmatch_table[DETECT_AL_TLS_JA3S_HASH].RegisterTests = DetectTlsJa3SHashRegisterTests;
86 #endif
89 
92 
95 
96  DetectBufferTypeSetDescriptionByName("ja3s.hash", "TLS JA3S hash");
97 
99  DetectTlsJa3SHashSetupCallback);
100 
102  DetectTlsJa3SHashValidateCallback);
103 
104  g_tls_ja3s_hash_buffer_id = DetectBufferTypeGetByName("ja3s.hash");
105 }
106 
107 /**
108  * \brief this function setup the ja3s.hash modifier keyword used in the rule
109  *
110  * \param de_ctx Pointer to the Detection Engine Context
111  * \param s Pointer to the Signature to which the current keyword belongs
112  * \param str Should hold an empty string always
113  *
114  * \retval 0 On success
115  * \retval -1 On failure
116  */
117 static int DetectTlsJa3SHashSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
118 {
119  if (DetectBufferSetActiveList(s, g_tls_ja3s_hash_buffer_id) < 0)
120  return -1;
121 
123  return -1;
124 
125  /* Check if JA3 is disabled */
126  if (!RunmodeIsUnittests() && Ja3IsDisabled("rule"))
127  return -1;
128 
129  return 0;
130 }
131 
132 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
133  const DetectEngineTransforms *transforms, Flow *f,
134  const uint8_t flow_flags, void *txv, const int list_id)
135 {
136  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
137  if (buffer->inspect == NULL) {
138  const SSLState *ssl_state = (SSLState *)f->alstate;
139 
140  if (ssl_state->server_connp.ja3_hash == NULL) {
141  return NULL;
142  }
143 
144  const uint32_t data_len = strlen(ssl_state->server_connp.ja3_hash);
145  const uint8_t *data = (uint8_t *)ssl_state->server_connp.ja3_hash;
146 
147  InspectionBufferSetup(buffer, data, data_len);
148  InspectionBufferApplyTransforms(buffer, transforms);
149  }
150 
151  return buffer;
152 }
153 
154 static _Bool DetectTlsJa3SHashValidateCallback(const Signature *s,
155  const char **sigerror)
156 {
157  const SigMatch *sm = s->init_data->smlists[g_tls_ja3s_hash_buffer_id];
158  for ( ; sm != NULL; sm = sm->next)
159  {
160  if (sm->type != DETECT_CONTENT)
161  continue;
162 
163  const DetectContentData *cd = (DetectContentData *)sm->ctx;
164 
165  if (cd->flags & DETECT_CONTENT_NOCASE) {
166  *sigerror = "ja3s.hash should not be used together with "
167  "nocase, since the rule is automatically "
168  "lowercased anyway which makes nocase redundant.";
169  SCLogWarning(SC_WARN_POOR_RULE, "rule %u: %s", s->id, *sigerror);
170  }
171 
172  if (cd->content_len == 32)
173  return TRUE;
174 
175  *sigerror = "Invalid length of the specified JA3S hash (should "
176  "be 32 characters long). This rule will therefore "
177  "never match.";
178  SCLogError(SC_ERR_INVALID_RULE_ARGUMENT, "rule %u: %s", s->id, *sigerror);
179  return FALSE;
180  }
181 
182  return TRUE;
183 }
184 
185 static void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
186  Signature *s)
187 {
188  SigMatch *sm = s->init_data->smlists[g_tls_ja3s_hash_buffer_id];
189  for ( ; sm != NULL; sm = sm->next)
190  {
191  if (sm->type != DETECT_CONTENT)
192  continue;
193 
195 
196  _Bool changed = FALSE;
197  uint32_t u;
198  for (u = 0; u < cd->content_len; u++)
199  {
200  if (isupper(cd->content[u])) {
201  cd->content[u] = tolower(cd->content[u]);
202  changed = TRUE;
203  }
204  }
205 
206  /* recreate the context if changes were made */
207  if (changed) {
208  SpmDestroyCtx(cd->spm_ctx);
209  cd->spm_ctx = SpmInitCtx(cd->content, cd->content_len, 1,
210  de_ctx->spm_global_thread_ctx);
211  }
212  }
213 }
214 
215 #ifdef UNITTESTS
217 #endif
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect.h:1409
SignatureInitData * init_data
Definition: detect.h:564
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1150
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition: detect.h:778
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
uint32_t id
Definition: detect.h:529
#define FALSE
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectMpmAppLayerRegistery *mpm_reg, int list_id)
SSLStateConnp server_connp
void DetectBufferTypeRegisterSetupCallback(const char *name, void(*SetupCallback)(const DetectEngineCtx *, Signature *))
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:1164
Signature container.
Definition: detect.h:496
#define TRUE
struct SigMatch_ * next
Definition: detect.h:326
main detection engine ctx
Definition: detect.h:724
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:242
#define SIGMATCH_INFO_STICKY_BUFFER
Definition: detect.h:1356
SpmCtx * SpmInitCtx(const uint8_t *needle, uint16_t needle_len, int nocase, SpmGlobalThreadCtx *global_thread_ctx)
Definition: util-spm.c:166
#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
int RunmodeIsUnittests(void)
Definition: suricata.c:261
uint8_t type
Definition: detect.h:323
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.
#define SCLogWarning(err_code,...)
Macro used to log WARNING messages.
Definition: util-debug.h:281
const char * desc
Definition: detect.h:1166
struct SigMatch_ ** smlists
Definition: detect.h:490
SigMatchCtx * ctx
Definition: detect.h:325
void DetectTlsJa3SHashRegister(void)
Registration function for keyword: ja3s.hash.
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:1332
void SpmDestroyCtx(SpmCtx *ctx)
Definition: util-spm.c:176
const char * url
Definition: detect.h:1167
int DetectBufferSetActiveList(Signature *s, const int list)
const uint8_t * inspect
Definition: detect.h:347
#define DOC_URL
Definition: suricata.h:86
void DetectBufferTypeSetDescriptionByName(const char *name, const char *desc)
#define DETECT_CONTENT_NOCASE
void DetectBufferTypeRegisterValidateCallback(const char *name, _Bool(*ValidateCallback)(const Signature *, const char **sigerror))
#define DOC_VERSION
Definition: suricata.h:91
uint16_t flags
Definition: detect.h:1158
Flow data structure.
Definition: flow.h:325
void(* RegisterTests)(void)
Definition: detect.h:1156
a single match condition for a signature
Definition: detect.h:322
void DetectAppLayerMpmRegister2(const char *name, int direction, int priority, int(*PrefilterRegister)(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectMpmAppLayerRegistery *mpm_reg, int list_id), InspectionBufferGetDataPtr GetData, AppProto alproto, int tx_min_progress)
register a MPM engine