1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
/* Copyright (C) 2017-2022 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Mats Klepsland <mats.klepsland@gmail.com>
*
* Implements support for tls.cert_serial keyword.
*/
#include "suricata-common.h"
#include "threads.h"
#include "decode.h"
#include "detect.h"
#include "detect-parse.h"
#include "detect-engine.h"
#include "detect-engine-mpm.h"
#include "detect-engine-prefilter.h"
#include "detect-content.h"
#include "detect-pcre.h"
#include "flow.h"
#include "flow-util.h"
#include "flow-var.h"
#include "util-debug.h"
#include "util-spm.h"
#include "util-print.h"
#include "stream-tcp.h"
#include "app-layer.h"
#include "app-layer-ssl.h"
#include "detect-tls-cert-serial.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
static int DetectTlsSerialSetup(DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectTlsSerialRegisterTests(void);
#endif
static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms,
Flow *f, const uint8_t flow_flags,
void *txv, const int list_id);
static void DetectTlsSerialSetupCallback(const DetectEngineCtx *de_ctx,
Signature *s);
static bool DetectTlsSerialValidateCallback(const Signature *s,
const char **sigerror);
static int g_tls_cert_serial_buffer_id = 0;
/**
* \brief Registration function for keyword: tls.cert_serial
*/
void DetectTlsSerialRegister(void)
{
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].name = "tls.cert_serial";
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].alias = "tls_cert_serial";
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].desc =
"sticky buffer to match the TLS cert serial buffer";
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].url = "/rules/tls-keywords.html#tls-cert-serial";
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].Setup = DetectTlsSerialSetup;
#ifdef UNITTESTS
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].RegisterTests = DetectTlsSerialRegisterTests;
#endif
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].flags |= SIGMATCH_NOOPT;
sigmatch_table[DETECT_AL_TLS_CERT_SERIAL].flags |= SIGMATCH_INFO_STICKY_BUFFER;
DetectAppLayerInspectEngineRegister2("tls.cert_serial", ALPROTO_TLS,
SIG_FLAG_TOCLIENT, TLS_STATE_CERT_READY,
DetectEngineInspectBufferGeneric, GetData);
DetectAppLayerMpmRegister2("tls.cert_serial", SIG_FLAG_TOCLIENT, 2,
PrefilterGenericMpmRegister, GetData, ALPROTO_TLS,
TLS_STATE_CERT_READY);
DetectAppLayerInspectEngineRegister2("tls.cert_serial", ALPROTO_TLS, SIG_FLAG_TOSERVER,
TLS_STATE_CERT_READY, DetectEngineInspectBufferGeneric, GetData);
DetectAppLayerMpmRegister2("tls.cert_serial", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,
GetData, ALPROTO_TLS, TLS_STATE_CERT_READY);
DetectBufferTypeSetDescriptionByName("tls.cert_serial",
"TLS certificate serial number");
DetectBufferTypeRegisterSetupCallback("tls.cert_serial",
DetectTlsSerialSetupCallback);
DetectBufferTypeRegisterValidateCallback("tls.cert_serial",
DetectTlsSerialValidateCallback);
g_tls_cert_serial_buffer_id = DetectBufferTypeGetByName("tls.cert_serial");
}
/**
* \brief this function setup the tls_cert_serial modifier keyword used in the rule
*
* \param de_ctx Pointer to the Detection Engine Context
* \param s Pointer to the Signature to which the current keyword belongs
* \param str Should hold an empty string always
*
* \retval 0 On success
* \retval -1 On failure
*/
static int DetectTlsSerialSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
{
if (DetectBufferSetActiveList(de_ctx, s, g_tls_cert_serial_buffer_id) < 0)
return -1;
if (DetectSignatureSetAppProto(s, ALPROTO_TLS) < 0)
return -1;
return 0;
}
static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
const DetectEngineTransforms *transforms, Flow *f,
const uint8_t flow_flags, void *txv, const int list_id)
{
InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
if (buffer->inspect == NULL) {
const SSLState *ssl_state = (SSLState *)f->alstate;
const SSLStateConnp *connp;
if (flow_flags & STREAM_TOSERVER) {
connp = &ssl_state->client_connp;
} else {
connp = &ssl_state->server_connp;
}
if (connp->cert0_serial == NULL) {
return NULL;
}
const uint32_t data_len = strlen(connp->cert0_serial);
const uint8_t *data = (uint8_t *)connp->cert0_serial;
InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
InspectionBufferApplyTransforms(buffer, transforms);
}
return buffer;
}
static bool DetectTlsSerialValidateCallback(const Signature *s,
const char **sigerror)
{
for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
if (s->init_data->buffers[x].id != (uint32_t)g_tls_cert_serial_buffer_id)
continue;
const SigMatch *sm = s->init_data->buffers[x].head;
for (; sm != NULL; sm = sm->next) {
if (sm->type != DETECT_CONTENT)
continue;
const DetectContentData *cd = (DetectContentData *)sm->ctx;
if (cd->flags & DETECT_CONTENT_NOCASE) {
*sigerror = "tls.cert_serial should not be used together "
"with nocase, since the rule is automatically "
"uppercased anyway which makes nocase redundant.";
SCLogWarning("rule %u: %s", s->id, *sigerror);
}
/* no need to worry about this if the content is short enough */
if (cd->content_len <= 2)
return true;
uint32_t u;
for (u = 0; u < cd->content_len; u++)
if (cd->content[u] == ':')
return true;
*sigerror = "No colon delimiters ':' detected in content after "
"tls.cert_serial. This rule will therefore never "
"match.";
SCLogWarning("rule %u: %s", s->id, *sigerror);
return false;
}
}
return true;
}
static void DetectTlsSerialSetupCallback(const DetectEngineCtx *de_ctx,
Signature *s)
{
for (uint32_t x = 0; x < s->init_data->buffer_index; x++) {
if (s->init_data->buffers[x].id != (uint32_t)g_tls_cert_serial_buffer_id)
continue;
SigMatch *sm = s->init_data->buffers[x].head;
for (; sm != NULL; sm = sm->next) {
if (sm->type != DETECT_CONTENT)
continue;
DetectContentData *cd = (DetectContentData *)sm->ctx;
bool changed = false;
uint32_t u;
for (u = 0; u < cd->content_len; u++) {
if (islower(cd->content[u])) {
cd->content[u] = u8_toupper(cd->content[u]);
changed = true;
}
}
/* recreate the context if changes were made */
if (changed) {
SpmDestroyCtx(cd->spm_ctx);
cd->spm_ctx =
SpmInitCtx(cd->content, cd->content_len, 1, de_ctx->spm_global_thread_ctx);
}
}
}
}
#ifdef UNITTESTS
#include "tests/detect-tls-cert-serial.c"
#endif
|
