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  /* try to enable JA3 */
126  SSLEnableJA3();
127 
128  /* Check if JA3 is disabled */
129  if (!RunmodeIsUnittests() && Ja3IsDisabled("rule")) {
131  SCLogError(SC_WARN_JA3_DISABLED, "ja3(s) support is not enabled");
132  }
133  return -2;
134  }
135 
136  return 0;
137 }
138 
139 static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
140  const DetectEngineTransforms *transforms, Flow *f,
141  const uint8_t flow_flags, void *txv, const int list_id)
142 {
143  InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
144  if (buffer->inspect == NULL) {
145  const SSLState *ssl_state = (SSLState *)f->alstate;
146 
147  if (ssl_state->server_connp.ja3_hash == NULL) {
148  return NULL;
149  }
150 
151  const uint32_t data_len = strlen(ssl_state->server_connp.ja3_hash);
152  const uint8_t *data = (uint8_t *)ssl_state->server_connp.ja3_hash;
153 
154  InspectionBufferSetup(buffer, data, data_len);
155  InspectionBufferApplyTransforms(buffer, transforms);
156  }
157 
158  return buffer;
159 }
160 
161 static _Bool DetectTlsJa3SHashValidateCallback(const Signature *s,
162  const char **sigerror)
163 {
164  const SigMatch *sm = s->init_data->smlists[g_tls_ja3s_hash_buffer_id];
165  for ( ; sm != NULL; sm = sm->next)
166  {
167  if (sm->type != DETECT_CONTENT)
168  continue;
169 
170  const DetectContentData *cd = (DetectContentData *)sm->ctx;
171 
172  if (cd->flags & DETECT_CONTENT_NOCASE) {
173  *sigerror = "ja3s.hash should not be used together with "
174  "nocase, since the rule is automatically "
175  "lowercased anyway which makes nocase redundant.";
176  SCLogWarning(SC_WARN_POOR_RULE, "rule %u: %s", s->id, *sigerror);
177  }
178 
179  if (cd->content_len == 32)
180  return TRUE;
181 
182  *sigerror = "Invalid length of the specified JA3S hash (should "
183  "be 32 characters long). This rule will therefore "
184  "never match.";
185  SCLogError(SC_ERR_INVALID_RULE_ARGUMENT, "rule %u: %s", s->id, *sigerror);
186  return FALSE;
187  }
188 
189  return TRUE;
190 }
191 
192 static void DetectTlsJa3SHashSetupCallback(const DetectEngineCtx *de_ctx,
193  Signature *s)
194 {
195  SigMatch *sm = s->init_data->smlists[g_tls_ja3s_hash_buffer_id];
196  for ( ; sm != NULL; sm = sm->next)
197  {
198  if (sm->type != DETECT_CONTENT)
199  continue;
200 
202 
203  _Bool changed = FALSE;
204  uint32_t u;
205  for (u = 0; u < cd->content_len; u++)
206  {
207  if (isupper(cd->content[u])) {
208  cd->content[u] = tolower(cd->content[u]);
209  changed = TRUE;
210  }
211  }
212 
213  /* recreate the context if changes were made */
214  if (changed) {
215  SpmDestroyCtx(cd->spm_ctx);
216  cd->spm_ctx = SpmInitCtx(cd->content, cd->content_len, 1,
217  de_ctx->spm_global_thread_ctx);
218  }
219  }
220 }
221 
222 #ifdef UNITTESTS
224 #endif
SigTableElmt sigmatch_table[DETECT_TBLSIZE]
Definition: detect.h:1448
SignatureInitData * init_data
Definition: detect.h:591
int(* Setup)(DetectEngineCtx *, Signature *, const char *)
Definition: detect.h:1186
SpmGlobalThreadCtx * spm_global_thread_ctx
Definition: detect.h:815
int DetectSignatureSetAppProto(Signature *s, AppProto alproto)
uint32_t id
Definition: detect.h:555
#define FALSE
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:263
InspectionBuffer * InspectionBufferGet(DetectEngineThreadCtx *det_ctx, const int list_id)
const char * name
Definition: detect.h:1200
Signature container.
Definition: detect.h:522
#define TRUE
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
struct SigMatch_ * next
Definition: detect.h:322
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
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
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
uint8_t type
Definition: detect.h:319
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:1202
struct SigMatch_ ** smlists
Definition: detect.h:516
int PrefilterGenericMpmRegister(DetectEngineCtx *de_ctx, SigGroupHead *sgh, MpmCtx *mpm_ctx, const DetectBufferMpmRegistery *mpm_reg, int list_id)
SigMatchCtx * ctx
Definition: detect.h:321
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:1369
void SpmDestroyCtx(SpmCtx *ctx)
Definition: util-spm.c:176
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)
#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:1194
Flow data structure.
Definition: flow.h:325
void(* RegisterTests)(void)
Definition: detect.h:1192
a single match condition for a signature
Definition: detect.h:318