/*
* tls.c - TLS/TLS/DTLS dissector
*
* Copyright (C) 2016-24 - ntop.org
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_TLS
#include "ndpi_api.h"
#include "ndpi_md5.h"
#include "ndpi_sha1.h"
#include "ndpi_sha256.h"
#include "ndpi_encryption.h"
#include "ndpi_private.h"
#define JA4R_DECIMAL 1
static void ndpi_search_tls_wrapper(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow);
// #define DEBUG_TLS_MEMORY 1
// #define DEBUG_TLS 1
// #define DEBUG_TLS_BLOCKS 1
// #define DEBUG_CERTIFICATE_HASH
// #define DEBUG_HEURISTIC
// #define DEBUG_JA 1
/* #define DEBUG_FINGERPRINT 1 */
/* #define DEBUG_ENCRYPTED_SNI 1 */
/* **************************************** */
/*
JA3
https://engineering.salesforce.com/tls-fingerprinting-with-ja3-and-ja3s-247362855967
JA4
https://github.com/FoxIO-LLC/ja4/blob/main/technical_details/JA4.md
*/
#define JA_STR_LEN 1024
#define MAX_NUM_JA 128
#define MAX_JA_STRLEN 256
union ja_info {
struct {
u_int16_t tls_handshake_version;
u_int16_t num_ciphers, cipher[MAX_NUM_JA];
u_int16_t num_tls_extensions, tls_extension[MAX_NUM_JA];
u_int16_t num_elliptic_curve, elliptic_curve[MAX_NUM_JA];
u_int16_t num_elliptic_curve_point_format, elliptic_curve_point_format[MAX_NUM_JA];
u_int16_t num_signature_algorithms, signature_algorithms[MAX_NUM_JA];
u_int16_t num_supported_versions, supported_versions[MAX_NUM_JA];
char signature_algorithms_str[MAX_JA_STRLEN], alpn[MAX_JA_STRLEN];
} client;
struct {
u_int16_t tls_handshake_version;
u_int16_t num_ciphers, cipher[MAX_NUM_JA];
u_int16_t num_tls_extensions, tls_extension[MAX_NUM_JA];
u_int16_t tls_supported_version;
u_int16_t num_elliptic_curve_point_format, elliptic_curve_point_format[MAX_NUM_JA];
char alpn[MAX_JA_STRLEN];
} server;
};
/*
NOTE
How to view the certificate fingerprint
1. Using wireshark save the certificate on certificate.bin file as explained
in https://security.stackexchange.com/questions/123851/how-can-i-extract-the-certificate-from-this-pcap-file
2. openssl x509 -inform der -in certificate.bin -text > certificate.der
3. openssl x509 -noout -fingerprint -sha1 -inform pem -in certificate.der
SHA1 Fingerprint=15:9A:76....
$ shasum -a 1 www.grc.com.bin
159a76.....
*/
#define NDPI_MAX_TLS_REQUEST_SIZE 10000
#define TLS_THRESHOLD 34387200 /* Threshold for certificate validity */
#define TLS_LIMIT_DATE 1598918400 /* From 01/09/2020 TLS certificates lifespan is limited to 13 months */
static void ndpi_int_tls_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow);
/* **************************************** */
static u_int32_t ndpi_tls_refine_master_protocol(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
u_int32_t protocol;
if(packet->tcp != NULL) {
/*
In case of TLS there are probably sub-protocols
such as IMAPS that can be otherwise detected
*/
u_int16_t sport = ntohs(packet->tcp->source);
u_int16_t dport = ntohs(packet->tcp->dest);
if(flow->stun.maybe_dtls)
protocol = NDPI_PROTOCOL_DTLS;
else if((sport == 465) || (dport == 465) || (sport == 587) || (dport == 587))
protocol = NDPI_PROTOCOL_MAIL_SMTPS;
else if((sport == 993) || (dport == 993) || (flow->l4.tcp.mail_imap_starttls))
protocol = NDPI_PROTOCOL_MAIL_IMAPS;
else if((sport == 995) || (dport == 995))
protocol = NDPI_PROTOCOL_MAIL_POPS;
else
protocol = NDPI_PROTOCOL_TLS;
} else {
protocol = NDPI_PROTOCOL_DTLS;
}
return protocol;
}
/* **************************************** */
static u_int32_t __get_master(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
if(flow->detected_protocol_stack[1] != NDPI_PROTOCOL_UNKNOWN)
return flow->detected_protocol_stack[1];
if(flow->detected_protocol_stack[0] != NDPI_PROTOCOL_UNKNOWN)
return flow->detected_protocol_stack[0];
return ndpi_tls_refine_master_protocol(ndpi_struct, flow);
}
/* **************************************** */
static int ndpi_search_tls_memory(const u_int8_t *payload,
u_int16_t payload_len,
u_int32_t seq,
message_t *message) {
u_int avail_bytes;
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Handling TLS flow [payload_len: %u][buffer_len: %u]\n",
payload_len,
message->buffer_len);
#endif
if(message->buffer == NULL) {
/* Allocate buffer */
message->buffer_len = 2048, message->buffer_used = 0;
message->buffer = (u_int8_t*)ndpi_malloc(message->buffer_len);
if(message->buffer == NULL)
return -1;
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Allocating %u buffer\n", message->buffer_len);
#endif
}
avail_bytes = message->buffer_len - message->buffer_used;
if(avail_bytes < payload_len) {
u_int new_len = message->buffer_len + payload_len - avail_bytes + 1;
void *newbuf = ndpi_realloc(message->buffer,
message->buffer_len, new_len);
if(!newbuf) return -1;
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Enlarging %u -> %u buffer\n", message->buffer_len, new_len);
#endif
message->buffer = (u_int8_t*)newbuf;
message->buffer_len = new_len;
avail_bytes = message->buffer_len - message->buffer_used;
}
if(payload_len > 0 && avail_bytes >= payload_len) {
u_int8_t ok = 0;
if(message->next_seq != 0) {
if(seq == message->next_seq)
ok = 1;
} else
ok = 1;
if(ok) {
memcpy(&message->buffer[message->buffer_used],
payload, payload_len);
message->buffer_used += payload_len;
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Copied data to buffer [%u/%u bytes][tcp_seq: %u][next: %u]\n",
message->buffer_used, message->buffer_len,
seq,
seq + payload_len);
#endif
message->next_seq = seq + payload_len;
} else {
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Skipping packet [%u bytes][tcp_seq: %u][expected next: %u]\n",
message->buffer_len,
seq,
message->next_seq);
#endif
}
}
return 0;
}
/* **************************************** */
static void cleanupServerName(char *buffer, u_int buffer_len) {
u_int i;
/* Now all lowecase */
for(i=0; i<buffer_len; i++)
buffer[i] = tolower(buffer[i]);
}
/* **************************************** */
/*
Return code
-1: error (buffer too short)
0: OK but buffer is not human readeable (so something went wrong)
1: OK
*/
static int extractRDNSequence(struct ndpi_packet_struct *packet,
u_int offset, char *buffer, u_int buffer_len,
char *rdnSeqBuf, u_int *rdnSeqBuf_offset,
u_int rdnSeqBuf_len,
const char *label) {
u_int8_t str_len, is_printable = 1;
char *str;
u_int len;
if(*rdnSeqBuf_offset >= rdnSeqBuf_len) {
#ifdef DEBUG_TLS
printf("[TLS] %s() [buffer capacity reached][%u]\n",
__FUNCTION__, rdnSeqBuf_len);
#endif
return -1;
}
if((offset+4) >= packet->payload_packet_len)
return(-1);
str_len = packet->payload[offset+4];
// packet is truncated... further inspection is not needed
if((offset+4+str_len) >= packet->payload_packet_len)
return(-1);
str = (char*)&packet->payload[offset+5];
len = (u_int)ndpi_min(str_len, buffer_len-1);
strncpy(buffer, str, len);
buffer[len] = '\0';
// check string is printable
is_printable = ndpi_normalize_printable_string(buffer, len);
if(is_printable) {
int rc = ndpi_snprintf(&rdnSeqBuf[*rdnSeqBuf_offset],
rdnSeqBuf_len-(*rdnSeqBuf_offset),
"%s%s=%s", (*rdnSeqBuf_offset > 0) ? ", " : "",
label, buffer);
if(rc > 0 && ((u_int)rc > rdnSeqBuf_len-(*rdnSeqBuf_offset)))
return -1; /* Truncated; not enough buffer */
if(rc > 0)
(*rdnSeqBuf_offset) += rc;
}
return(is_printable);
}
/* **************************************** */
static u_int64_t make_tls_cert_key(struct ndpi_packet_struct *packet, int is_from_client)
{
u_int64_t key;
/* Server ip/port */
if(packet->iphv6 == NULL) {
if(packet->tcp) {
if(is_from_client)
key = ((u_int64_t)packet->iph->daddr << 32) | packet->tcp->dest;
else
key = ((u_int64_t)packet->iph->saddr << 32) | packet->tcp->source;
} else {
if(is_from_client)
key = ((u_int64_t)packet->iph->daddr << 32) | packet->udp->dest;
else
key = ((u_int64_t)packet->iph->saddr << 32) | packet->udp->source;
}
} else {
if(packet->tcp) {
if(is_from_client)
key = (ndpi_quick_hash64((const char *)&packet->iphv6->ip6_dst, 16) << 16) | packet->tcp->dest;
else
key = (ndpi_quick_hash64((const char *)&packet->iphv6->ip6_src, 16) << 16) | packet->tcp->source;
} else {
if(is_from_client)
key = (ndpi_quick_hash64((const char *)&packet->iphv6->ip6_dst, 16) << 16) | packet->udp->dest;
else
key = (ndpi_quick_hash64((const char *)&packet->iphv6->ip6_src, 16) << 16) | packet->udp->source;
}
}
return key;
}
/* **************************************** */
static void checkTLSSubprotocol(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow,
int is_from_client) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
if(ndpi_struct->cfg.tls_subclassification_enabled &&
flow->detected_protocol_stack[1] == NDPI_PROTOCOL_UNKNOWN) {
/* Subprotocol not yet set */
if(ndpi_struct->tls_cert_cache) {
u_int16_t cached_proto;
u_int64_t key;
key = make_tls_cert_key(packet, is_from_client);
if(ndpi_lru_find_cache(ndpi_struct->tls_cert_cache, key,
&cached_proto, 0 /* Don't remove it as it can be used for other connections */,
ndpi_get_current_time(flow))) {
ndpi_protocol ret = { { __get_master(ndpi_struct, flow), cached_proto }, NDPI_PROTOCOL_UNKNOWN /* unused */, NDPI_PROTOCOL_CATEGORY_UNSPECIFIED, NULL};
ndpi_set_detected_protocol(ndpi_struct, flow, cached_proto, __get_master(ndpi_struct, flow), NDPI_CONFIDENCE_DPI_CACHE);
flow->category = ndpi_get_proto_category(ndpi_struct, ret);
ndpi_check_subprotocol_risk(ndpi_struct, flow, cached_proto);
ndpi_unset_risk(flow, NDPI_NUMERIC_IP_HOST);
}
}
}
}
/* **************************************** */
/* See https://blog.catchpoint.com/2017/05/12/dissecting-tls-using-wireshark/ */
void processCertificateElements(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow,
u_int16_t p_offset, u_int16_t certificate_len) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
u_int16_t num_found = 0;
int32_t i;
char buffer[64] = { '\0' }, rdnSeqBuf[2048];
u_int rdn_len = 0;
rdnSeqBuf[0] = '\0';
#ifdef DEBUG_TLS
printf("[TLS] %s() [offset: %u][certificate_len: %u]\n", __FUNCTION__, p_offset, certificate_len);
#endif
/* Check after handshake protocol header (5 bytes) and message header (4 bytes) */
for(i = p_offset; i < certificate_len - 2; i++) {
/*
See https://www.ibm.com/support/knowledgecenter/SSFKSJ_7.5.0/com.ibm.mq.sec.doc/q009860_.htm
for X.509 certificate labels
*/
if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x04) && (packet->payload[i+2] == 0x03)) {
/* Common Name */
int rc = extractRDNSequence(packet, i, buffer, sizeof(buffer), rdnSeqBuf, &rdn_len, sizeof(rdnSeqBuf), "CN");
if(rc == -1) break;
#ifdef DEBUG_TLS
printf("[TLS] %s() [%s][%s: %s]\n", __FUNCTION__, (num_found == 0) ? "Subject" : "Issuer", "Common Name", buffer);
#endif
} else if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x04) && (packet->payload[i+2] == 0x06)) {
/* Country */
int rc = extractRDNSequence(packet, i, buffer, sizeof(buffer), rdnSeqBuf, &rdn_len, sizeof(rdnSeqBuf), "C");
if(rc == -1) break;
#ifdef DEBUG_TLS
printf("[TLS] %s() [%s][%s: %s]\n", __FUNCTION__, (num_found == 0) ? "Subject" : "Issuer", "Country", buffer);
#endif
} else if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x04) && (packet->payload[i+2] == 0x07)) {
/* Locality */
int rc = extractRDNSequence(packet, i, buffer, sizeof(buffer), rdnSeqBuf, &rdn_len, sizeof(rdnSeqBuf), "L");
if(rc == -1) break;
#ifdef DEBUG_TLS
printf("[TLS] %s() [%s][%s: %s]\n", __FUNCTION__, (num_found == 0) ? "Subject" : "Issuer", "Locality", buffer);
#endif
} else if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x04) && (packet->payload[i+2] == 0x08)) {
/* State or Province */
int rc = extractRDNSequence(packet, i, buffer, sizeof(buffer), rdnSeqBuf, &rdn_len, sizeof(rdnSeqBuf), "ST");
if(rc == -1) break;
#ifdef DEBUG_TLS
printf("[TLS] %s() [%s][%s: %s]\n", __FUNCTION__, (num_found == 0) ? "Subject" : "Issuer", "State or Province", buffer);
#endif
} else if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x04) && (packet->payload[i+2] == 0x0a)) {
/* Organization Name */
int rc = extractRDNSequence(packet, i, buffer, sizeof(buffer), rdnSeqBuf, &rdn_len, sizeof(rdnSeqBuf), "O");
if(rc == -1) break;
#ifdef DEBUG_TLS
printf("[TLS] %s() [%s][%s: %s]\n", __FUNCTION__, (num_found == 0) ? "Subject" : "Issuer", "Organization Name", buffer);
#endif
} else if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x04) && (packet->payload[i+2] == 0x0b)) {
/* Organization Unit */
int rc = extractRDNSequence(packet, i, buffer, sizeof(buffer), rdnSeqBuf, &rdn_len, sizeof(rdnSeqBuf), "OU");
if(rc == -1) break;
#ifdef DEBUG_TLS
printf("[TLS] %s() [%s][%s: %s]\n", __FUNCTION__, (num_found == 0) ? "Subject" : "Issuer", "Organization Unit", buffer);
#endif
} else if((packet->payload[i] == 0x30) && (packet->payload[i+1] == 0x1e) && (packet->payload[i+2] == 0x17)) {
/* Certificate Validity */
u_int offset = i+4;
if(num_found == 0) {
num_found++;
#ifdef DEBUG_TLS
printf("[TLS] %s() IssuerDN [%s]\n", __FUNCTION__, rdnSeqBuf);
#endif
if(rdn_len && (flow->protos.tls_quic.issuerDN == NULL)) {
flow->protos.tls_quic.issuerDN = ndpi_strdup(rdnSeqBuf);
if(ndpi_normalize_printable_string(rdnSeqBuf, rdn_len) == 0) {
char str[64];
snprintf(str, sizeof(str), "Invalid issuerDN %s", flow->protos.tls_quic.issuerDN);
ndpi_set_risk(flow, NDPI_INVALID_CHARACTERS, str);
}
}
rdn_len = 0; /* Reset buffer */
}
if(i + 3 < certificate_len &&
(offset+packet->payload[i+3]) < packet->payload_packet_len) {
char utcDate[32];
u_int8_t len = packet->payload[i+3];
#ifdef DEBUG_TLS
u_int j;
printf("[CERTIFICATE] notBefore [len: %u][", len);
for(j=0; j<len; j++) printf("%c", packet->payload[i+4+j]);
printf("]\n");
#endif
if(len < (sizeof(utcDate)-1)) {
struct tm utc;
utc.tm_isdst = -1; /* Not set by strptime */
strncpy(utcDate, (const char*)&packet->payload[i+4], len);
utcDate[len] = '\0';
/* 141021000000Z */
if(strptime(utcDate, "%y%m%d%H%M%SZ", &utc) != NULL) {
flow->protos.tls_quic.notBefore = timegm(&utc);
#ifdef DEBUG_TLS
printf("[CERTIFICATE] notBefore %u [%s]\n",
flow->protos.tls_quic.notBefore, utcDate);
#endif
}
}
offset += len;
if((offset+1) < packet->payload_packet_len) {
len = packet->payload[offset+1];
offset += 2;
if((offset+len) < packet->payload_packet_len) {
u_int32_t time_sec = packet->current_time_ms / 1000;
#ifdef DEBUG_TLS
u_int j;
printf("[CERTIFICATE] notAfter [len: %u][", len);
for(j=0; j<len; j++) printf("%c", packet->payload[offset+j]);
printf("]\n");
#endif
if(len < (sizeof(utcDate)-1)) {
struct tm utc;
utc.tm_isdst = -1; /* Not set by strptime */
strncpy(utcDate, (const char*)&packet->payload[offset], len);
utcDate[len] = '\0';
/* 141021000000Z */
if(strptime(utcDate, "%y%m%d%H%M%SZ", &utc) != NULL) {
flow->protos.tls_quic.notAfter = timegm(&utc);
#ifdef DEBUG_TLS
printf("[CERTIFICATE] notAfter %u [%s]\n",
flow->protos.tls_quic.notAfter, utcDate);
#endif
}
}
if(flow->protos.tls_quic.notBefore > TLS_LIMIT_DATE)
if((flow->protos.tls_quic.notAfter-flow->protos.tls_quic.notBefore) > TLS_THRESHOLD) {
char str[64];
snprintf(str, sizeof(str), "TLS Cert lasts %u days",
(flow->protos.tls_quic.notAfter-flow->protos.tls_quic.notBefore) / 86400);
ndpi_set_risk(flow, NDPI_TLS_CERT_VALIDITY_TOO_LONG, str); /* Certificate validity longer than 13 months */
}
if((time_sec < flow->protos.tls_quic.notBefore) || (time_sec > flow->protos.tls_quic.notAfter)) {
char str[96], b[32], e[32];
struct tm result;
time_t theTime;
theTime = flow->protos.tls_quic.notBefore;
strftime(b, sizeof(b), "%d/%b/%Y %H:%M:%S", ndpi_gmtime_r(&theTime, &result));
theTime = flow->protos.tls_quic.notAfter;
strftime(e, sizeof(e), "%d/%b/%Y %H:%M:%S", ndpi_gmtime_r(&theTime, &result));
snprintf(str, sizeof(str), "%s - %s", b, e);
ndpi_set_risk(flow, NDPI_TLS_CERTIFICATE_EXPIRED, str); /* Certificate expired */
} else if((time_sec > flow->protos.tls_quic.notBefore)
&& (time_sec > (flow->protos.tls_quic.notAfter - (ndpi_struct->cfg.tls_certificate_expire_in_x_days * 86400)))) {
char str[96], b[32], e[32];
struct tm result;
time_t theTime;
theTime = flow->protos.tls_quic.notBefore;
strftime(b, sizeof(b), "%d/%b/%Y %H:%M:%S", ndpi_gmtime_r(&theTime, &result));
theTime = flow->protos.tls_quic.notAfter;
strftime(e, sizeof(e), "%d/%b/%Y %H:%M:%S", ndpi_gmtime_r(&theTime, &result));
snprintf(str, sizeof(str), "%s - %s", b, e);
ndpi_set_risk(flow, NDPI_TLS_CERTIFICATE_ABOUT_TO_EXPIRE, str); /* Certificate almost expired */
}
}
}
}
} else if((packet->payload[i] == 0x55) && (packet->payload[i+1] == 0x1d) && (packet->payload[i+2] == 0x11)) {
/* Organization OID: 2.5.29.17 (subjectAltName) */
u_int8_t matched_name = 0;
/* If the client hello was not observed or the requested name was missing, there is no need to trigger an alert */
if(flow->host_server_name[0] == '\0')
matched_name = 1;
#ifdef DEBUG_TLS
printf("******* [TLS] Found subjectAltName\n");
#endif
i += 3 /* skip the initial patten 55 1D 11 */;
/* skip the first type, 0x04 == BIT STRING, and jump to it's length */
if(i < packet->payload_packet_len && packet->payload[i] == 0x04) i++; else i += 4; /* 4 bytes, with the last byte set to 04 */
if(i < packet->payload_packet_len) {
i += (packet->payload[i] & 0x80) ? (packet->payload[i] & 0x7F) : 0; /* skip BIT STRING length */
if(i < packet->payload_packet_len) {
i += 2; /* skip the second type, 0x30 == SEQUENCE, and jump to it's length */
if(i < packet->payload_packet_len) {
i += (packet->payload[i] & 0x80) ? (packet->payload[i] & 0x7F) : 0; /* skip SEQUENCE length */
i++;
while(i < packet->payload_packet_len) {
u_int8_t general_name_type = packet->payload[i];
if((general_name_type == 0x81) /* rfc822Name */
|| (general_name_type == 0x82) /* dNSName */
|| (general_name_type == 0x87) /* ipAddress */
)
{
if((i < (packet->payload_packet_len - 1))
&& ((i + packet->payload[i + 1] + 2) < packet->payload_packet_len)) {
u_int8_t len = packet->payload[i + 1];
char dNSName[256];
u_int16_t dNSName_len;
i += 2;
/* The check "len > sizeof(dNSName) - 1" will be always false. If we add it,
the compiler is smart enough to detect it and throws a warning */
if((len == 0 /* Looks something went wrong */)
|| ((i+len) > packet->payload_packet_len))
break;
if(general_name_type == 0x87) {
if(len == 4 /* IPv4 */) {
ndpi_snprintf(dNSName, sizeof(dNSName), "%u.%u.%u.%u",
packet->payload[i] & 0xFF,
packet->payload[i+1] & 0xFF,
packet->payload[i+2] & 0xFF,
packet->payload[i+3] & 0xFF);
} else if(len == 16 /* IPv6 */) {
struct in6_addr addr = *(struct in6_addr *)&packet->payload[i];
inet_ntop(AF_INET6, &addr, dNSName, sizeof(dNSName));
} else {
/* Is that possibile? Better safe than sorry */
dNSName[0] = '\0';
}
} else {
strncpy(dNSName, (const char*)&packet->payload[i], len);
dNSName[len] = '\0';
}
dNSName_len = strlen(dNSName);
cleanupServerName(dNSName, dNSName_len);
#if DEBUG_TLS
printf("[TLS] dNSName %s [%s][len: %u][leftover: %d]\n", dNSName,
flow->host_server_name, len,
packet->payload_packet_len-i-len);
#endif
/*
We cannot use ndpi_is_valid_hostname() as we can have wildcards
here that will create false positives
*/
if(ndpi_normalize_printable_string(dNSName, dNSName_len) == 0) {
ndpi_set_risk(flow, NDPI_INVALID_CHARACTERS, dNSName);
/* This looks like an attack */
ndpi_set_risk(flow, NDPI_POSSIBLE_EXPLOIT, "Invalid dNSName name");
}
if(matched_name == 0) {
#if DEBUG_TLS
printf("[TLS] Trying to match '%s' with '%s'\n",
flow->host_server_name,
dNSName);
#endif
if(dNSName[0] == '*') {
char * label = strstr(flow->host_server_name, &dNSName[1]);
if(label != NULL) {
char * first_dot = strchr(flow->host_server_name, '.');
if((first_dot == NULL) || (first_dot <= label)) {
matched_name = 1;
}
}
}
else if(strcmp(flow->host_server_name, dNSName) == 0) {
matched_name = 1;
}
}
if(flow->protos.tls_quic.server_names == NULL)
flow->protos.tls_quic.server_names = ndpi_strdup(dNSName),
flow->protos.tls_quic.server_names_len = strlen(dNSName);
else if((u_int16_t)(flow->protos.tls_quic.server_names_len + dNSName_len + 1) > flow->protos.tls_quic.server_names_len) {
u_int16_t newstr_len = flow->protos.tls_quic.server_names_len + dNSName_len + 1;
char *newstr = (char*)ndpi_realloc(flow->protos.tls_quic.server_names,
flow->protos.tls_quic.server_names_len+1, newstr_len+1);
if(newstr) {
flow->protos.tls_quic.server_names = newstr;
flow->protos.tls_quic.server_names[flow->protos.tls_quic.server_names_len] = ',';
strncpy(&flow->protos.tls_quic.server_names[flow->protos.tls_quic.server_names_len+1],
dNSName, dNSName_len+1);
flow->protos.tls_quic.server_names[newstr_len] = '\0';
flow->protos.tls_quic.server_names_len = newstr_len;
}
}
if(ndpi_struct->cfg.tls_subclassification_enabled &&
!flow->protos.tls_quic.subprotocol_detected) {
if(ndpi_match_hostname_protocol(ndpi_struct, flow, __get_master(ndpi_struct, flow), dNSName, dNSName_len)) {
flow->protos.tls_quic.subprotocol_detected = 1;
ndpi_unset_risk(flow, NDPI_NUMERIC_IP_HOST);
}
}
i += len;
} else {
char buf[32];
snprintf(buf, sizeof(buf), "Unknown extension %02X", general_name_type);
#if DEBUG_TLS
printf("[TLS] Leftover %u bytes", packet->payload_packet_len - i);
#endif
ndpi_set_risk(flow, NDPI_TLS_SUSPICIOUS_EXTENSION, buf);
break;
}
} else {
break;
}
} /* while */
if(!matched_name) {
char str[128];
snprintf(str, sizeof(str), "%s vs %s", flow->host_server_name, flow->protos.tls_quic.server_names);
ndpi_set_risk(flow, NDPI_TLS_CERTIFICATE_MISMATCH, str); /* Certificate mismatch */
}
}
}
}
}
} /* for */
if(rdn_len && (flow->protos.tls_quic.subjectDN == NULL)) {
flow->protos.tls_quic.subjectDN = ndpi_strdup(rdnSeqBuf);
if(ndpi_struct->cfg.tls_subclassification_enabled &&
flow->detected_protocol_stack[1] == NDPI_PROTOCOL_UNKNOWN) {
/* No idea what is happening behind the scenes: let's check the certificate */
u_int32_t val;
int rc = ndpi_match_string_value(ndpi_struct->tls_cert_subject_automa.ac_automa,
rdnSeqBuf, strlen(rdnSeqBuf), &val);
if(rc == 0) {
/* Match found */
u_int16_t proto_id = (u_int16_t)val;
ndpi_protocol ret = { { __get_master(ndpi_struct, flow), proto_id }, NDPI_PROTOCOL_UNKNOWN /* unused */, NDPI_PROTOCOL_CATEGORY_UNSPECIFIED, NULL};
ndpi_set_detected_protocol(ndpi_struct, flow, proto_id, __get_master(ndpi_struct, flow), NDPI_CONFIDENCE_DPI);
flow->category = ndpi_get_proto_category(ndpi_struct, ret);
ndpi_check_subprotocol_risk(ndpi_struct, flow, proto_id);
ndpi_unset_risk(flow, NDPI_NUMERIC_IP_HOST);
if(ndpi_struct->tls_cert_cache) {
u_int64_t key = make_tls_cert_key(packet, 0 /* from the server */);
ndpi_lru_add_to_cache(ndpi_struct->tls_cert_cache, key, proto_id, ndpi_get_current_time(flow));
}
}
}
}
if(flow->protos.tls_quic.subjectDN && flow->protos.tls_quic.issuerDN
&& (!strcmp(flow->protos.tls_quic.subjectDN, flow->protos.tls_quic.issuerDN))) {
/* Last resort: we check if this is a trusted issuerDN */
if(ndpi_check_issuerdn_risk_exception(ndpi_struct, flow->protos.tls_quic.issuerDN))
return; /* This is a trusted DN */
if(!flow->protos.tls_quic.webrtc)
ndpi_set_risk(flow, NDPI_TLS_SELFSIGNED_CERTIFICATE, flow->protos.tls_quic.subjectDN);
}
#if DEBUG_TLS
printf("[TLS] %s() SubjectDN [%s]\n", __FUNCTION__, rdnSeqBuf);
#endif
}
/* **************************************** */
/* See https://blog.catchpoint.com/2017/05/12/dissecting-tls-using-wireshark/ */
int processCertificate(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
int is_dtls = packet->udp || flow->stun.maybe_dtls; /* No certificate with QUIC */
u_int32_t certificates_length, length = (packet->payload[1] << 16) + (packet->payload[2] << 8) + packet->payload[3];
u_int32_t certificates_offset = 7 + (is_dtls ? 8 : 0);
u_int8_t num_certificates_found = 0;
#ifdef DEBUG_TLS
printf("[TLS] %s() [payload_packet_len=%u][direction: %u][%02X %02X %02X %02X %02X %02X...]\n",
__FUNCTION__, packet->payload_packet_len,
packet->packet_direction,
packet->payload[0], packet->payload[1], packet->payload[2],
packet->payload[3], packet->payload[4], packet->payload[5]);
#endif
if((packet->payload_packet_len != (length + 4 + (is_dtls ? 8 : 0))) || (packet->payload[1] != 0x0) ||
certificates_offset >= packet->payload_packet_len) {
ndpi_set_risk(flow, NDPI_MALFORMED_PACKET, "Unvalid lenght");
return(-1); /* Invalid length */
}
certificates_length = (packet->payload[certificates_offset - 3] << 16) +
(packet->payload[certificates_offset - 2] << 8) +
packet->payload[certificates_offset - 1];
if((packet->payload[certificates_offset - 3] != 0x0) || ((certificates_length+3) != length)) {
ndpi_set_risk(flow, NDPI_MALFORMED_PACKET, "Invalid certificate offset");
return(-2); /* Invalid length */
}
/* Now let's process each individual certificates */
while(certificates_offset < certificates_length) {
u_int32_t certificate_len = (packet->payload[certificates_offset] << 16) + (packet->payload[certificates_offset+1] << 8) + packet->payload[certificates_offset+2];
/* Invalid lenght */
if((certificate_len == 0)
|| (packet->payload[certificates_offset] != 0x0)
|| ((certificates_offset+certificate_len) > (4+certificates_length+(is_dtls ? 8 : 0)))) {
#ifdef DEBUG_TLS
printf("[TLS] Invalid length [certificate_len: %u][certificates_offset: %u][%u vs %u]\n",
certificate_len, certificates_offset,
(certificates_offset+certificate_len),
certificates_length);
#endif
break;
}
certificates_offset += 3;
#ifdef DEBUG_TLS
printf("[TLS] Processing %u bytes certificate [%02X %02X %02X]\n",
certificate_len,
packet->payload[certificates_offset],
packet->payload[certificates_offset+1],
packet->payload[certificates_offset+2]);
#endif
if(num_certificates_found++ == 0) /* Dissect only the first certificate that is the one we care */ {
#ifdef DEBUG_CERTIFICATE_HASH
{
u_int32_t i;
for(i=0;i<certificate_len;i++)
printf("%02X ", packet->payload[certificates_offset+i]);
printf("\n");
}
#endif
/* For SHA-1 we take into account only the first certificate and not all of them */
if(ndpi_struct->cfg.tls_sha1_fingerprint_enabled) {
SHA1_CTX srv_cert_fingerprint_ctx ;
SHA1Init(&srv_cert_fingerprint_ctx);
SHA1Update(&srv_cert_fingerprint_ctx,
&packet->payload[certificates_offset],
certificate_len);
SHA1Final(flow->protos.tls_quic.sha1_certificate_fingerprint, &srv_cert_fingerprint_ctx);
flow->protos.tls_quic.fingerprint_set = 1;
uint8_t * sha1 = flow->protos.tls_quic.sha1_certificate_fingerprint;
const size_t sha1_siz = sizeof(flow->protos.tls_quic.sha1_certificate_fingerprint);
char sha1_str[20 /* sha1_siz */ * 2 + 1];
static const char hexalnum[] = "0123456789ABCDEF";
size_t i;
for (i = 0; i < sha1_siz; ++i) {
u_int8_t lower = (sha1[i] & 0x0F);
u_int8_t upper = (sha1[i] & 0xF0) >> 4;
sha1_str[i*2] = hexalnum[upper];
sha1_str[i*2 + 1] = hexalnum[lower];
}
sha1_str[sha1_siz * 2] = '\0';
#ifdef DEBUG_TLS
printf("[TLS] SHA-1: %s\n", sha1_str);
#endif
if(ndpi_struct->malicious_sha1_hashmap != NULL) {
u_int16_t rc1 = ndpi_hash_find_entry(ndpi_struct->malicious_sha1_hashmap, sha1_str, sha1_siz * 2, NULL);
if(rc1 == 0)
ndpi_set_risk(flow, NDPI_MALICIOUS_SHA1_CERTIFICATE, sha1_str);
}
}
processCertificateElements(ndpi_struct, flow, certificates_offset, certificate_len);
}
certificates_offset += certificate_len;
}
if((ndpi_struct->num_tls_blocks_to_follow != 0)
&& (flow->l4.tcp.tls.num_tls_blocks >= ndpi_struct->num_tls_blocks_to_follow)) {
#ifdef DEBUG_TLS_BLOCKS
printf("*** [TLS Block] Enough blocks dissected\n");
#endif
flow->extra_packets_func = NULL; /* We're good now */
}
return(1);
}
/* **************************************** */
static int processTLSBlock(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
int ret;
int is_dtls = packet->udp || flow->stun.maybe_dtls;
#ifdef DEBUG_TLS
printf("[TLS] Processing block %u\n", packet->payload[0]);
#endif
switch(packet->payload[0] /* block type */) {
case 0x01: /* Client Hello */
flow->protos.tls_quic.client_hello_processed = 1;
flow->protos.tls_quic.ch_direction = packet->packet_direction;
processClientServerHello(ndpi_struct, flow, 0);
ndpi_int_tls_add_connection(ndpi_struct, flow);
#ifdef DEBUG_TLS
printf("*** TLS [version: %02X][Client Hello]\n",
flow->protos.tls_quic.ssl_version);
#endif
checkTLSSubprotocol(ndpi_struct, flow, packet->payload[0] == 0x01);
break;
case 0x02: /* Server Hello */
flow->protos.tls_quic.server_hello_processed = 1;
flow->protos.tls_quic.ch_direction = !packet->packet_direction;
processClientServerHello(ndpi_struct, flow, 0);
ndpi_int_tls_add_connection(ndpi_struct, flow);
#ifdef DEBUG_TLS
printf("*** TLS [version: %02X][Server Hello]\n",
flow->protos.tls_quic.ssl_version);
#endif
if(!is_dtls && flow->protos.tls_quic.ssl_version >= 0x0304 /* TLS 1.3 */) {
flow->tls_quic.certificate_processed = 1; /* No Certificate with TLS 1.3+ */
}
if(is_dtls && flow->protos.tls_quic.ssl_version == 0xFEFC /* DTLS 1.3 */) {
flow->tls_quic.certificate_processed = 1; /* No Certificate with DTLS 1.3+ */
}
checkTLSSubprotocol(ndpi_struct, flow, packet->payload[0] == 0x01);
break;
case 0x0b: /* Certificate */
/* Important: populate the tls union fields only after
* ndpi_int_tls_add_connection has been called */
if(flow->protos.tls_quic.client_hello_processed ||
flow->protos.tls_quic.server_hello_processed) {
/* Only certificates from the server */
if(flow->protos.tls_quic.ch_direction != packet->packet_direction) {
ret = processCertificate(ndpi_struct, flow);
if(ret != 1) {
#ifdef DEBUG_TLS
printf("[TLS] Error processing certificate: %d\n", ret);
#endif
}
} else {
#ifdef DEBUG_TLS
printf("[TLS] Certificate from client. Ignoring it\n");
#endif
}
flow->tls_quic.certificate_processed = 1;
}
break;
default:
return(-1);
}
return(0);
}
/* **************************************** */
static void ndpi_looks_like_tls(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
if(flow->guessed_protocol_id == NDPI_PROTOCOL_UNKNOWN)
flow->guessed_protocol_id = __get_master(ndpi_struct, flow);
}
/* **************************************** */
static int ndpi_search_tls_tcp(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
u_int8_t something_went_wrong = 0;
message_t *message;
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] ndpi_search_tls_tcp() Processing new packet [payload_packet_len: %u][Dir: %u]\n",
packet->payload_packet_len, packet->packet_direction);
#endif
/* This function is also called by "extra dissection" data path. Unfortunately,
generic "extra function" code doesn't honour protocol bitmask.
TODO: handle that in ndpi_main.c for all the protocols */
if(packet->payload_packet_len == 0 ||
packet->tcp_retransmission) {
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Ack or retransmission %d/%d. Skip\n",
packet->payload_packet_len, packet->tcp_retransmission);
#endif
return 1; /* Keep working */
}
message = &flow->tls_quic.message[packet->packet_direction];
if(ndpi_search_tls_memory(packet->payload,
packet->payload_packet_len, ntohl(packet->tcp->seq),
message) == -1)
return 0; /* Error -> stop */
/* Valid TLS Content Types:
https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-5 */
if(!(message->buffer[0] >= 20 &&
message->buffer[0] <= 26)) {
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
something_went_wrong = 1;
}
while(!something_went_wrong) {
u_int32_t len;
u_int16_t p_len;
const u_int8_t *p;
u_int8_t content_type;
if(message->buffer_used < 5)
break;
len = (message->buffer[3] << 8) + message->buffer[4] + 5;
if(len > message->buffer_used) {
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Not enough TLS data [%u < %u][%02X %02X %02X %02X %02X]\n",
len, message->buffer_used,
message->buffer[0],
message->buffer[1],
message->buffer[2],
message->buffer[3],
message->buffer[4]);
#endif
break;
}
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Processing %u bytes message\n", len);
#endif
content_type = message->buffer[0];
/* Overwriting packet payload */
p = packet->payload;
p_len = packet->payload_packet_len; /* Backup */
if(content_type == 0x14 /* Change Cipher Spec */) {
if(ndpi_struct->skip_tls_blocks_until_change_cipher) {
/*
Ignore Application Data up until change cipher
so in this case we reset the number of observed
TLS blocks
*/
flow->l4.tcp.tls.num_tls_blocks = 0;
}
if(len == 6 &&
message->buffer[1] == 0x03 && /* TLS >= 1.0 */
((message->buffer[3] << 8) + (message->buffer[4])) == 1) {
#ifdef DEBUG_TLS
printf("[TLS] Change Cipher Spec\n");
#endif
ndpi_int_tls_add_connection(ndpi_struct, flow);
flow->l4.tcp.tls.app_data_seen[packet->packet_direction] = 1;
/* Further data is encrypted so we are not able to parse it without
erros and without setting `something_went_wrong` variable */
break;
}
} else if(content_type == 0x15 /* Alert */) {
/* https://techcommunity.microsoft.com/t5/iis-support-blog/ssl-tls-alert-protocol-and-the-alert-codes/ba-p/377132 */
#ifdef DEBUG_TLS
printf("[TLS] *** TLS ALERT ***\n");
#endif
if(len >= 7) {
u_int8_t alert_level = message->buffer[5];
if(alert_level == 2 /* Warning (1), Fatal (2) */)
ndpi_set_risk(flow, NDPI_TLS_FATAL_ALERT, "Found fatal TLS alert");
}
u_int16_t const alert_len = ntohs(*(u_int16_t const *)&message->buffer[3]);
if (message->buffer[1] == 0x03 &&
message->buffer[2] <= 0x04 &&
alert_len == (u_int32_t)message->buffer_used - 5)
{
ndpi_int_tls_add_connection(ndpi_struct, flow);
}
}
if((len > 9)
&& (content_type != 0x17 /* Application Data */)) {
/* Split the element in blocks */
u_int32_t processed = 5;
while((processed+4) <= len) {
const u_int8_t *block = (const u_int8_t *)&message->buffer[processed];
u_int32_t block_len = (block[1] << 16) + (block[2] << 8) + block[3];
if(/* (block_len == 0) || */ /* Note blocks can have zero lenght */
(block_len > len) || ((block[1] != 0x0))) {
something_went_wrong = 1;
break;
}
packet->payload = block;
packet->payload_packet_len = ndpi_min(block_len+4, message->buffer_used);
if((processed+packet->payload_packet_len) > len) {
something_went_wrong = 1;
break;
}
processTLSBlock(ndpi_struct, flow);
ndpi_looks_like_tls(ndpi_struct, flow);
processed += packet->payload_packet_len;
}
} else if(len > 5 /* Minimum block size */) {
/* Process element as a whole */
if(content_type == 0x17 /* Application Data */) {
u_int32_t block_len = (message->buffer[3] << 8) + (message->buffer[4]);
/* Let's do a quick check to make sure this really looks like TLS */
if(block_len < 16384 /* Max TLS block size */)
ndpi_looks_like_tls(ndpi_struct, flow);
if (message->buffer[1] == 0x03 &&
message->buffer[2] <= 0x04 &&
block_len == (u_int32_t)message->buffer_used - 5)
{
ndpi_int_tls_add_connection(ndpi_struct, flow);
}
/* If we have seen Application Data blocks in both directions, it means
we are after the handshake. Stop extra processing */
flow->l4.tcp.tls.app_data_seen[packet->packet_direction] = 1;
if(flow->l4.tcp.tls.app_data_seen[!packet->packet_direction] == 1)
flow->tls_quic.certificate_processed = 1;
if(flow->tls_quic.certificate_processed) {
if(flow->l4.tcp.tls.num_tls_blocks < ndpi_struct->num_tls_blocks_to_follow) {
int16_t blen = len-5;
/* Use positive values for c->s e negative for s->c */
if(packet->packet_direction != 0) blen = -blen;
flow->l4.tcp.tls.tls_application_blocks_len[flow->l4.tcp.tls.num_tls_blocks++] = blen;
}
#ifdef DEBUG_TLS_BLOCKS
printf("*** [TLS Block] [len: %u][num_tls_blocks: %u/%u]\n",
len-5, flow->l4.tcp.tls.num_tls_blocks, ndpi_struct->num_tls_blocks_to_follow);
#endif
}
}
}
packet->payload = p;
packet->payload_packet_len = p_len; /* Restore */
message->buffer_used -= len;
if(message->buffer_used > 0)
memmove(message->buffer, &message->buffer[len], message->buffer_used);
else
break;
#ifdef DEBUG_TLS_MEMORY
printf("[TLS Mem] Left memory buffer %u bytes\n", message->buffer_used);
#endif
}
if(something_went_wrong
|| ((ndpi_struct->num_tls_blocks_to_follow > 0)
&& (flow->l4.tcp.tls.num_tls_blocks == ndpi_struct->num_tls_blocks_to_follow))
|| ((ndpi_struct->num_tls_blocks_to_follow == 0)
&& (/* Common path: found handshake on both directions */
(flow->tls_quic.certificate_processed == 1 && flow->protos.tls_quic.client_hello_processed) ||
/* No handshake at all but Application Data on both directions */
(flow->l4.tcp.tls.app_data_seen[0] == 1 && flow->l4.tcp.tls.app_data_seen[1] == 1) ||
/* Handshake on one direction and Application Data on the other */
(flow->protos.tls_quic.client_hello_processed && flow->l4.tcp.tls.app_data_seen[!flow->protos.tls_quic.ch_direction] == 1) ||
(flow->protos.tls_quic.server_hello_processed && flow->l4.tcp.tls.app_data_seen[flow->protos.tls_quic.ch_direction] == 1)))
) {
#ifdef DEBUG_TLS_BLOCKS
printf("*** [TLS Block] No more blocks\n");
#endif
/* An ookla flow? */
if((ndpi_struct->cfg.ookla_aggressiveness & NDPI_AGGRESSIVENESS_OOKLA_TLS) && /* Feature enabled */
(!something_went_wrong &&
flow->tls_quic.certificate_processed == 1 &&
flow->protos.tls_quic.client_hello_processed == 1 &&
flow->protos.tls_quic.server_hello_processed == 1) && /* TLS handshake found without errors */
flow->detected_protocol_stack[0] == NDPI_PROTOCOL_TLS && /* No IMAPS/FTPS/... */
flow->detected_protocol_stack[1] == NDPI_PROTOCOL_UNKNOWN && /* No sub-classification */
ntohs(flow->s_port) == 8080 && /* Ookla port */
ookla_search_into_cache(ndpi_struct, flow)) {
NDPI_LOG_INFO(ndpi_struct, "found ookla (cache over TLS)\n");
/* Even if a LRU cache is involved, NDPI_CONFIDENCE_DPI_AGGRESSIVE seems more
suited than NDPI_CONFIDENCE_DPI_CACHE */
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_OOKLA, NDPI_PROTOCOL_TLS, NDPI_CONFIDENCE_DPI_AGGRESSIVE);
/* TLS over port 8080 usually triggers that risk; clear it */
ndpi_unset_risk(flow, NDPI_KNOWN_PROTOCOL_ON_NON_STANDARD_PORT);
flow->extra_packets_func = NULL;
return(0); /* That's all */
} else {
flow->extra_packets_func = NULL;
return(0); /* That's all */
}
} else
return(1);
}
/* **************************************** */
int is_dtls(const u_int8_t *buf, u_int32_t buf_len, u_int32_t *block_len) {
if(buf_len <= 13)
return 0;
if((buf[0] != 0x16 && buf[0] != 0x14 && buf[0] != 0x17 && buf[0] != 0x15) || /* Handshake, change-cipher-spec, Application-Data, Alert */
!((buf[1] == 0xfe && buf[2] == 0xff) || /* Versions */
(buf[1] == 0xfe && buf[2] == 0xfd) ||
(buf[1] == 0xfe && buf[2] == 0xfc) ||
(buf[1] == 0x01 && buf[2] == 0x00))) {
#ifdef DEBUG_TLS
printf("[TLS] DTLS invalid block 0x%x or old version 0x%x-0x%x-0x%x\n",
buf[0], buf[1], buf[2], buf[3]);
#endif
return 0;
}
*block_len = ntohs(*((u_int16_t*)&buf[11]));
#ifdef DEBUG_TLS
printf("[TLS] DTLS block len: %d\n", *block_len);
#endif
if(*block_len == 0 || (*block_len + 12 >= buf_len)) { /* We might have multiple DTLS records */
#ifdef DEBUG_TLS
printf("[TLS] DTLS invalid block len %d (buf_len %d)\n",
*block_len, buf_len);
#endif
return 0;
}
return 1;
}
/* **************************************** */
static int ndpi_search_tls_udp(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
u_int32_t handshake_len, handshake_frag_off, handshake_frag_len;
u_int16_t p_len, processed;
const u_int8_t *p;
u_int8_t no_dtls = 0, change_cipher_found = 0;
message_t *message = NULL;
#ifdef DEBUG_TLS
printf("[TLS] %s()\n", __FUNCTION__);
#endif
/* Overwriting packet payload */
p = packet->payload, p_len = packet->payload_packet_len; /* Backup */
/* Split the element in blocks */
processed = 0;
while(processed + 13 < p_len) {
u_int32_t block_len;
const u_int8_t *block = (const u_int8_t *)&p[processed];
if(!is_dtls(block, p_len, &block_len)) {
no_dtls = 1;
break;
}
/* We process only handshake msgs */
if(block[0] == 0x16) {
if(processed + block_len + 13 > p_len) {
#ifdef DEBUG_TLS
printf("[TLS] DTLS invalid len %d %d %d\n", processed, block_len, p_len);
#endif
no_dtls = 1;
break;
}
/* TODO: handle (certificate) fragments */
if(block_len > 24) {
handshake_len = (block[14] << 16) + (block[15] << 8) + block[16];
handshake_frag_off = (block[19] << 16) + (block[20] << 8) + block[21];
handshake_frag_len = (block[22] << 16) + (block[23] << 8) + block[24];
message = &flow->tls_quic.message[packet->packet_direction];
#ifdef DEBUG_TLS
printf("[TLS] DTLS frag off %d len %d\n", handshake_frag_off, handshake_frag_len);
#endif
if((handshake_len + 12) == block_len) {
packet->payload = &block[13];
packet->payload_packet_len = block_len;
processTLSBlock(ndpi_struct, flow);
} else if(handshake_len + 12 > block_len) {
int rc;
#ifdef DEBUG_TLS
printf("[TLS] DTLS fragment off %d len %d\n", handshake_frag_off, handshake_frag_len);
#endif
if(handshake_frag_len + 12 > block_len) {
#ifdef DEBUG_TLS
printf("[TLS] DTLS fragment invalid len %d + 12 > %d\n", handshake_frag_len, block_len);
#endif
no_dtls = 1;
break;
}
if(handshake_frag_off == 0) {
rc = ndpi_search_tls_memory(&block[13],
handshake_frag_len + 12,
handshake_frag_off, message);
} else {
rc = ndpi_search_tls_memory(&block[13 + 12],
handshake_frag_len,
handshake_frag_off + 12, message);
}
if(rc == -1) {
no_dtls = 1;
break;
}
#ifdef DEBUG_TLS
printf("[TLS] DTLS reassembled len %d vs %d\n",
message->buffer_used, handshake_len + 12);
#endif
if(handshake_len + 12 == message->buffer_used) {
packet->payload = message->buffer;
packet->payload_packet_len = message->buffer_used;
processTLSBlock(ndpi_struct, flow);
ndpi_free(message->buffer);
memset(message, '\0', sizeof(*message));
message = NULL;
} else {
/* No break, next fragments might be in the same packet */
}
} else {
#ifdef DEBUG_TLS
printf("[TLS] DTLS invalid handshake_len %d, %d\n",
handshake_len, block_len);
#endif
no_dtls = 1;
break;
}
}
} else if(block[0] == 0x14) {
/* Change-cipher-spec: any subsequent block might be encrypted */
#ifdef DEBUG_TLS
printf("[TLS] Change-cipher-spec\n");
#endif
change_cipher_found = 1;
processed += block_len + 13;
flow->tls_quic.certificate_processed = 1; /* Fake, to avoid extra dissection */
break;
} else if(block[0] == 0x15 /* Alert */) {
#ifdef DEBUG_TLS
printf("[TLS] TLS Alert\n");
#endif
if(block_len == 2) {
u_int8_t alert_level = block[13];
if(alert_level == 2 /* Warning (1), Fatal (2) */)
ndpi_set_risk(flow, NDPI_TLS_FATAL_ALERT, "Found fatal TLS alert");
}
} else {
#ifdef DEBUG_TLS
printf("[TLS] Appllication Data\n");
#endif
processed += block_len + 13;
/* DTLS mid session: no need to further inspect the flow */
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_DTLS, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
ndpi_protocol ret = { { __get_master(ndpi_struct, flow), NDPI_PROTOCOL_UNKNOWN }, NDPI_PROTOCOL_UNKNOWN /* unused */, NDPI_PROTOCOL_CATEGORY_UNSPECIFIED, NULL};
flow->category = ndpi_get_proto_category(ndpi_struct, ret);
flow->tls_quic.certificate_processed = 1; /* Fake, to avoid extra dissection */
break;
}
processed += block_len + 13;
}
if(processed != p_len && message == NULL /* No pending reassembler */) {
#ifdef DEBUG_TLS
printf("[TLS] DTLS invalid processed len %d/%d (%d)\n", processed, p_len, change_cipher_found);
#endif
if(!change_cipher_found)
no_dtls = 1;
}
packet->payload = p;
packet->payload_packet_len = p_len; /* Restore */
if(no_dtls || change_cipher_found || flow->tls_quic.certificate_processed) {
NDPI_EXCLUDE_PROTO_EXT(ndpi_struct, flow, NDPI_PROTOCOL_DTLS);
return(0); /* That's all */
} else {
return(1); /* Keep working */
}
}
/* **************************************** */
static void tlsInitExtraPacketProcessing(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
/* At most 12 packets should almost always be enough to find the server certificate if it's there.
Exception: DTLS traffic with fragments, retransmissions and STUN packets */
flow->max_extra_packets_to_check = ((packet->udp != NULL) ? 20 : 12) + (ndpi_struct->num_tls_blocks_to_follow*4);
flow->extra_packets_func = (packet->udp != NULL) ? ndpi_search_tls_udp : ndpi_search_tls_tcp;
}
/* **************************************** */
void switch_extra_dissection_to_tls(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow)
{
#ifdef DEBUG_TLS
printf("Switching to TLS extra dissection\n");
#endif
/* Reset reassemblers */
if(flow->tls_quic.message[0].buffer)
ndpi_free(flow->tls_quic.message[0].buffer);
memset(&flow->tls_quic.message[0], '\0', sizeof(flow->tls_quic.message[0]));
if(flow->tls_quic.message[1].buffer)
ndpi_free(flow->tls_quic.message[1].buffer);
memset(&flow->tls_quic.message[1], '\0', sizeof(flow->tls_quic.message[1]));
tlsInitExtraPacketProcessing(ndpi_struct, flow);
}
/* **************************************** */
void switch_to_tls(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow, int first_time)
{
#ifdef DEBUG_TLS
printf("Switching to TLS\n");
#endif
if(first_time) {
/* Reset reassemblers */
if(flow->tls_quic.message[0].buffer)
ndpi_free(flow->tls_quic.message[0].buffer);
memset(&flow->tls_quic.message[0], '\0', sizeof(flow->tls_quic.message[0]));
if(flow->tls_quic.message[1].buffer)
ndpi_free(flow->tls_quic.message[1].buffer);
memset(&flow->tls_quic.message[1], '\0', sizeof(flow->tls_quic.message[1]));
}
ndpi_search_tls_wrapper(ndpi_struct, flow);
}
/* **************************************** */
static void tls_subclassify_by_alpn(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
/* Right now we have only one rule so we can keep it trivial */
if(strlen(flow->protos.tls_quic.advertised_alpns) > NDPI_STATICSTRING_LEN("anydesk/") &&
strncmp(flow->protos.tls_quic.advertised_alpns, "anydesk/", NDPI_STATICSTRING_LEN("anydesk/")) == 0) {
#ifdef DEBUG_TLS
printf("Matching ANYDESK via alpn\n");
#endif
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_ANYDESK,
__get_master(ndpi_struct, flow), NDPI_CONFIDENCE_DPI);
flow->protos.tls_quic.subprotocol_detected = 1;
}
}
/* **************************************** */
static void tlsCheckUncommonALPN(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow,
char *alpn_start) {
char * comma_or_nul = alpn_start;
do {
size_t alpn_len;
comma_or_nul = strchr(comma_or_nul, ',');
if(comma_or_nul == NULL)
comma_or_nul = alpn_start + strlen(alpn_start);
alpn_len = comma_or_nul - alpn_start;
if(!is_a_common_alpn(ndpi_struct, alpn_start, alpn_len)) {
char str[64];
size_t str_len;
#ifdef DEBUG_TLS
printf("TLS uncommon ALPN found: %.*s\n", (int)alpn_len, alpn_start);
#endif
str[0] = '\0';
str_len = ndpi_min(alpn_len, sizeof(str));
if(str_len > 0) {
strncpy(str, alpn_start, str_len);
str[str_len - 1] = '\0';
}
ndpi_set_risk(flow, NDPI_TLS_UNCOMMON_ALPN, str);
break;
}
alpn_start = comma_or_nul + 1;
} while (*(comma_or_nul++) != '\0');
}
/* **************************************** */
static void ndpi_int_tls_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
u_int32_t protocol;
#if DEBUG_TLS
printf("[TLS] %s()\n", __FUNCTION__);
#endif
if((flow->detected_protocol_stack[0] != NDPI_PROTOCOL_UNKNOWN) ||
(flow->detected_protocol_stack[1] != NDPI_PROTOCOL_UNKNOWN)) {
if(!flow->extra_packets_func)
tlsInitExtraPacketProcessing(ndpi_struct, flow);
return;
}
protocol = __get_master(ndpi_struct, flow);
ndpi_set_detected_protocol(ndpi_struct, flow, protocol, protocol, NDPI_CONFIDENCE_DPI);
/* We don't want to ovewrite STUN extra dissection, if enabled */
if(!flow->extra_packets_func)
tlsInitExtraPacketProcessing(ndpi_struct, flow);
}
/* **************************************** */
static void checkExtensions(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct * const flow, int is_dtls,
u_int16_t extension_id, u_int16_t extension_len,
u_int16_t extension_payload_offset) {
struct ndpi_packet_struct const * const packet = &ndpi_struct->packet;
if((extension_payload_offset + extension_len) > packet->payload_packet_len) {
#ifdef DEBUG_TLS
printf("[TLS] extension length exceeds remaining packet length: %u > %u.\n",
extension_len, packet->payload_packet_len - extension_payload_offset);
#endif
ndpi_set_risk(flow, NDPI_TLS_SUSPICIOUS_EXTENSION, "Invalid extension len");
return;
}
/* see: https://www.wireshark.org/docs/wsar_html/packet-tls-utils_8h_source.html */
static u_int16_t const allowed_non_iana_extensions[] = {
65486 /* ESNI */, 13172 /* NPN - Next Proto Neg */, 17513 /* ALPS */,
30032 /* Channel ID */, 65445 /* QUIC transport params */,
/* GREASE extensions */
2570, 6682, 10794, 14906, 19018, 23130, 27242,
31354, 35466, 39578, 43690, 47802, 51914, 56026,
60138, 64250,
/* Groups */
1035, 10794, 16696, 23130, 31354, 35466, 51914,
/* Ciphers */
102, 129, 52243, 52244, 57363, 65279, 65413,
/* ECH */
65037
};
size_t const allowed_non_iana_extensions_size = sizeof(allowed_non_iana_extensions) /
sizeof(allowed_non_iana_extensions[0]);
/* see: https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
if(extension_id > 59 && extension_id != 65281)
{
u_int8_t extension_found = 0;
size_t i;
for (i = 0; i < allowed_non_iana_extensions_size; ++i) {
if(allowed_non_iana_extensions[i] == extension_id) {
extension_found = 1;
break;
}
}
if(extension_found == 0) {
char str[64];
snprintf(str, sizeof(str), "Extn id %u", extension_id);
#ifdef DEBUG_TLS
printf("[TLS] suspicious extension id: %u\n", extension_id);
#endif
ndpi_set_risk(flow, NDPI_TLS_SUSPICIOUS_EXTENSION, str);
return;
}
}
/* Check for DTLS-only extensions. */
if(is_dtls == 0)
{
if(extension_id == 53 || extension_id == 54)
{
char str[64];
snprintf(str, sizeof(str), "Extn id %u", extension_id);
#ifdef DEBUG_TLS
printf("[TLS] suspicious DTLS-only extension id: %u\n", extension_id);
#endif
ndpi_set_risk(flow, NDPI_TLS_SUSPICIOUS_EXTENSION, str);
return;
}
}
}
/* **************************************** */
static int check_sni_is_numeric_ip(char *sni) {
unsigned char buf[sizeof(struct in6_addr)];
if(inet_pton(AF_INET, sni, buf) == 1)
return 1;
if(inet_pton(AF_INET6, sni, buf) == 1)
return 1;
return 0;
}
/* **************************************** */
static int u_int16_t_cmpfunc(const void * a, const void * b) { return(*(u_int16_t*)a - *(u_int16_t*)b); }
static bool is_grease_version(u_int16_t version) {
switch(version) {
case 0x0a0a:
case 0x1a1a:
case 0x2a2a:
case 0x3a3a:
case 0x4a4a:
case 0x5a5a:
case 0x6a6a:
case 0x7a7a:
case 0x8a8a:
case 0x9a9a:
case 0xaaaa:
case 0xbaba:
case 0xcaca:
case 0xdada:
case 0xeaea:
case 0xfafa:
return(true);
default:
return(false);
}
}
/* **************************************** */
static void ndpi_compute_ja4(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow,
u_int32_t quic_version,
union ja_info *ja) {
u_int8_t tmp_str[JA_STR_LEN];
u_int tmp_str_len, num_extn;
u_int8_t sha_hash[NDPI_SHA256_BLOCK_SIZE];
u_int16_t ja_str_len, i;
int rc;
u_int16_t tls_handshake_version = ja->client.tls_handshake_version;
char * const ja_str = &flow->protos.tls_quic.ja4_client[0];
const u_int16_t ja_max_len = sizeof(flow->protos.tls_quic.ja4_client);
bool is_dtls = ((flow->l4_proto == IPPROTO_UDP) && (quic_version == 0)) || flow->stun.maybe_dtls;
int ja4_r_len = 0;
char ja4_r[1024];
/*
Compute JA4 TLS/QUIC client
https://github.com/FoxIO-LLC/ja4/blob/main/technical_details/JA4.md
(QUIC=”q”, DTLS="d" or TCP=”t”)
(2 character TLS version)
(SNI=”d” or no SNI=”i”)
(2 character count of ciphers)
(2 character count of extensions)
(first and last characters of first ALPN extension value)
_
(sha256 hash of the list of cipher hex codes sorted in hex order, truncated to 12 characters)
_
(sha256 hash of (the list of extension hex codes sorted in hex order)_(the list of signature algorithms), truncated to 12 characters)
*/
ja_str[0] = is_dtls ? 'd' : ((quic_version != 0) ? 'q' : 't');
for(i=0; i<ja->client.num_supported_versions; i++) {
if((!is_grease_version(ja->client.supported_versions[i]))
&& (tls_handshake_version < ja->client.supported_versions[i]))
tls_handshake_version = ja->client.supported_versions[i];
}
switch(tls_handshake_version) {
case 0x0304: /* TLS 1.3 = “13” */
ja_str[1] = '1';
ja_str[2] = '3';
break;
case 0x0303: /* TLS 1.2 = “12” */
ja_str[1] = '1';
ja_str[2] = '2';
break;
case 0x0302: /* TLS 1.1 = “11” */
ja_str[1] = '1';
ja_str[2] = '1';
break;
case 0x0301: /* TLS 1.0 = “10” */
ja_str[1] = '1';
ja_str[2] = '0';
break;
case 0x0300: /* SSL 3.0 = “s3” */
ja_str[1] = 's';
ja_str[2] = '3';
break;
case 0x0200: /* SSL 2.0 = “s2” */
ja_str[1] = 's';
ja_str[2] = '2';
break;
case 0x0100: /* SSL 1.0 = “s1” */
ja_str[1] = 's';
ja_str[2] = '3';
break;
case 0xFEFF: /* DTLS 1.0 = “d1” */
ja_str[1] = 'd';
ja_str[2] = '1';
break;
case 0xFEFD: /* DTLS 1.2 = “d2” */
ja_str[1] = 'd';
ja_str[2] = '2';
break;
case 0xFEFC: /* DTLS 1.3 = “d3” */
ja_str[1] = 'd';
ja_str[2] = '3';
break;
default:
ja_str[1] = '0';
ja_str[2] = '0';
break;
}
ja_str[3] = ndpi_isset_risk(flow, NDPI_NUMERIC_IP_HOST) ? 'i' : 'd', ja_str_len = 4;
/* JA4_a */
rc = ndpi_snprintf(&ja_str[ja_str_len], ja_max_len - ja_str_len, "%02u%02u%c%c_",
ja->client.num_ciphers, ja->client.num_tls_extensions,
(ja->client.alpn[0] == '\0') ? '0' : ja->client.alpn[0],
(ja->client.alpn[0] == '\0') ? '0' : ja->client.alpn[1]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc;
/* Sort ciphers and extensions */
qsort(&ja->client.cipher, ja->client.num_ciphers, sizeof(u_int16_t), u_int16_t_cmpfunc);
qsort(&ja->client.tls_extension, ja->client.num_tls_extensions, sizeof(u_int16_t), u_int16_t_cmpfunc);
tmp_str_len = 0;
for(i=0; i<ja->client.num_ciphers; i++) {
#ifdef JA4R_DECIMAL
rc = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "%s%u", (i > 0) ? "," : "", ja->client.cipher[i]);
if(rc > 0) ja4_r_len += rc;
#endif
rc = ndpi_snprintf((char *)&tmp_str[tmp_str_len], JA_STR_LEN-tmp_str_len, "%s%04x",
(i > 0) ? "," : "", ja->client.cipher[i]);
if((rc > 0) && (tmp_str_len + rc < JA_STR_LEN)) tmp_str_len += rc; else break;
}
#ifndef JA4R_DECIMAL
ja_str[ja_str_len] = 0;
i = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "%s", ja_str); if(i > 0) ja4_r_len += i;
tmp_str[tmp_str_len] = 0;
i = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "%s_", tmp_str); if(i > 0) ja4_r_len += i;
#endif
ndpi_sha256(tmp_str, tmp_str_len, sha_hash);
rc = ndpi_snprintf(&ja_str[ja_str_len], ja_max_len - ja_str_len,
"%02x%02x%02x%02x%02x%02x_",
sha_hash[0], sha_hash[1], sha_hash[2],
sha_hash[3], sha_hash[4], sha_hash[5]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc;
#ifdef DEBUG_JA
printf("[CIPHER] %s [len: %u]\n", tmp_str, tmp_str_len);
#endif
#ifdef JA4R_DECIMAL
rc = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "_");
if(rc > 0) ja4_r_len += rc;
#endif
tmp_str_len = 0;
for(i=0, num_extn = 0; i<ja->client.num_tls_extensions; i++) {
if((ja->client.tls_extension[i] > 0) && (ja->client.tls_extension[i] != 0x10 /* ALPN extension */)) {
#ifdef JA4R_DECIMAL
rc = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "%s%u", (num_extn > 0) ? "," : "", ja->client.tls_extension[i]);
if((rc > 0) && (ja4_r_len + rc < JA_STR_LEN)) ja4_r_len += rc; else break;
#endif
rc = ndpi_snprintf((char *)&tmp_str[tmp_str_len], JA_STR_LEN-tmp_str_len, "%s%04x",
(num_extn > 0) ? "," : "", ja->client.tls_extension[i]);
if((rc > 0) && (tmp_str_len + rc < JA_STR_LEN)) tmp_str_len += rc; else break;
num_extn++;
}
}
for(i=0; i<ja->client.num_signature_algorithms; i++) {
rc = ndpi_snprintf((char *)&tmp_str[tmp_str_len], JA_STR_LEN-tmp_str_len, "%s%04x",
(i > 0) ? "," : "_", ja->client.signature_algorithms[i]);
if((rc > 0) && (tmp_str_len + rc < JA_STR_LEN)) tmp_str_len += rc; else break;
}
#ifdef DEBUG_JA
printf("[EXTN] %s [len: %u]\n", tmp_str, tmp_str_len);
#endif
tmp_str[tmp_str_len] = 0;
#ifndef JA4R_DECIMAL
i = snprintf(&ja4_r[ja4_r_len], sizeof(ja4_r)-ja4_r_len, "%s", tmp_str); if(i > 0) ja4_r_len += i;
#endif
if(ndpi_struct->cfg.tls_ja4r_fingerprint_enabled) {
if(flow->protos.tls_quic.ja4_client_raw == NULL)
flow->protos.tls_quic.ja4_client_raw = ndpi_strdup(ja4_r);
#ifdef DEBUG_JA
printf("[JA4_r] %s [len: %u]\n", ja4_r, ja4_r_len);
#endif
}
ndpi_sha256(tmp_str, tmp_str_len, sha_hash);
rc = ndpi_snprintf(&ja_str[ja_str_len], ja_max_len - ja_str_len,
"%02x%02x%02x%02x%02x%02x",
sha_hash[0], sha_hash[1], sha_hash[2],
sha_hash[3], sha_hash[4], sha_hash[5]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc;
ja_str[36] = 0;
#ifdef DEBUG_JA
printf("[JA4] %s [len: %lu]\n", ja_str, strlen(ja_str));
#endif
}
/* **************************************** */
int processClientServerHello(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow, u_int32_t quic_version) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
union ja_info ja;
u_int8_t invalid_ja = 0;
u_int16_t tls_version;
u_int32_t i, j;
u_int16_t total_len;
u_int8_t handshake_type;
bool is_quic = (quic_version != 0);
bool is_dtls = (packet->udp && !is_quic) || flow->stun.maybe_dtls;
#ifdef DEBUG_TLS
printf("TLS %s() called\n", __FUNCTION__);
#endif
handshake_type = packet->payload[0];
total_len = (packet->payload[1] << 16) + (packet->payload[2] << 8) + packet->payload[3];
if((total_len > packet->payload_packet_len) || (packet->payload[1] != 0x0))
return(0); /* Not found */
total_len = packet->payload_packet_len;
/* At least "magic" 3 bytes, null for string end, otherwise no need to waste cpu cycles */
if(total_len > 4) {
u_int16_t base_offset = (!is_dtls) ? 38 : 46;
u_int16_t version_offset = (!is_dtls) ? 4 : 12;
u_int16_t offset = (!is_dtls) ? 38 : 46;
u_int32_t tot_extension_len;
u_int8_t session_id_len = 0;
if((base_offset >= total_len) ||
(version_offset + 1) >= total_len)
return 0; /* Not found */
session_id_len = packet->payload[base_offset];
#ifdef DEBUG_TLS
printf("TLS [len: %u][handshake_type: %02X]\n", packet->payload_packet_len, handshake_type);
#endif
tls_version = ntohs(*((u_int16_t*)&packet->payload[version_offset]));
if(handshake_type == 0x02 /* Server Hello */) {
int rc;
ja.server.num_ciphers = 0;
ja.server.num_tls_extensions = 0;
ja.server.num_elliptic_curve_point_format = 0;
ja.server.alpn[0] = '\0';
ja.server.tls_handshake_version = tls_version;
#ifdef DEBUG_TLS
printf("TLS Server Hello [version: 0x%04X]\n", tls_version);
#endif
/*
The server hello decides about the TLS version of this flow
https://networkengineering.stackexchange.com/questions/55752/why-does-wireshark-show-version-tls-1-2-here-instead-of-tls-1-3
*/
if(packet->udp)
offset += session_id_len + 1;
else {
if(tls_version < 0x7F15 /* TLS 1.3 lacks of session id */)
offset += session_id_len+1;
}
if((offset+3) > packet->payload_packet_len)
return(0); /* Not found */
ja.server.num_ciphers = 1, ja.server.cipher[0] = ntohs(*((u_int16_t*)&packet->payload[offset]));
if((flow->protos.tls_quic.server_unsafe_cipher = ndpi_is_safe_ssl_cipher(ja.server.cipher[0])) == 1) {
char str[64];
char unknown_cipher[8];
snprintf(str, sizeof(str), "Cipher %s", ndpi_cipher2str(ja.server.cipher[0], unknown_cipher));
ndpi_set_risk(flow, NDPI_TLS_WEAK_CIPHER, str);
}
flow->protos.tls_quic.server_cipher = ja.server.cipher[0];
#ifdef DEBUG_TLS
printf("TLS [server][session_id_len: %u][cipher: %04X]\n", session_id_len, ja.server.cipher[0]);
#endif
offset += 2 + 1;
if((offset + 1) < packet->payload_packet_len) /* +1 because we are goint to read 2 bytes */
tot_extension_len = ntohs(*((u_int16_t*)&packet->payload[offset]));
else
tot_extension_len = 0;
#ifdef DEBUG_TLS
printf("TLS [server][tot_extension_len: %u]\n", tot_extension_len);
#endif
offset += 2;
for(i=0; i<tot_extension_len; ) {
u_int16_t extension_id;
u_int32_t extension_len;
if((offset+4) > packet->payload_packet_len) break;
extension_id = ntohs(*((u_int16_t*)&packet->payload[offset]));
extension_len = ntohs(*((u_int16_t*)&packet->payload[offset+2]));
if(offset+4+extension_len > packet->payload_packet_len) {
break;
}
if(ja.server.num_tls_extensions < MAX_NUM_JA)
ja.server.tls_extension[ja.server.num_tls_extensions++] = extension_id;
#ifdef DEBUG_TLS
printf("TLS [server][extension_id: %u/0x%04X][len: %u]\n",
extension_id, extension_id, extension_len);
#endif
checkExtensions(ndpi_struct, flow, is_dtls, extension_id, extension_len, offset + 4);
if(extension_id == 43 /* supported versions */) {
if(extension_len >= 2) {
u_int16_t tls_version = ntohs(*((u_int16_t*)&packet->payload[offset+4]));
#ifdef DEBUG_TLS
printf("TLS [server] [TLS version: 0x%04X]\n", tls_version);
#endif
flow->protos.tls_quic.ssl_version = ja.server.tls_supported_version = tls_version;
}
} else if(extension_id == 16 /* application_layer_protocol_negotiation (ALPN) */ &&
offset + 6 < packet->payload_packet_len) {
u_int16_t s_offset = offset+4;
u_int16_t tot_alpn_len = ntohs(*((u_int16_t*)&packet->payload[s_offset]));
char alpn_str[256];
u_int16_t alpn_str_len = 0, i;
#ifdef DEBUG_TLS
printf("Server TLS [ALPN: block_len=%u/len=%u]\n", extension_len, tot_alpn_len);
#endif
s_offset += 2;
tot_alpn_len += s_offset;
if(tot_alpn_len > packet->payload_packet_len)
return 0;
while(s_offset < tot_alpn_len && s_offset < total_len) {
u_int8_t alpn_i, alpn_len = packet->payload[s_offset++];
if((s_offset + alpn_len) <= tot_alpn_len) {
#ifdef DEBUG_TLS
printf("Server TLS [ALPN: %u]\n", alpn_len);
#endif
if(((uint32_t)alpn_str_len+alpn_len+1) < (sizeof(alpn_str)-1)) {
if(alpn_str_len > 0) {
alpn_str[alpn_str_len] = ',';
alpn_str_len++;
}
for(alpn_i=0; alpn_i<alpn_len; alpn_i++) {
alpn_str[alpn_str_len+alpn_i] = packet->payload[s_offset+alpn_i];
}
s_offset += alpn_len, alpn_str_len += alpn_len;;
} else {
alpn_str[alpn_str_len] = '\0';
ndpi_set_risk(flow, NDPI_TLS_UNCOMMON_ALPN, alpn_str);
break;
}
} else {
alpn_str[alpn_str_len] = '\0';
ndpi_set_risk(flow, NDPI_TLS_UNCOMMON_ALPN, alpn_str);
break;
}
} /* while */
alpn_str[alpn_str_len] = '\0';
#ifdef DEBUG_TLS
printf("Server TLS [ALPN: %s][len: %u]\n", alpn_str, alpn_str_len);
#endif
if(ndpi_normalize_printable_string(alpn_str, alpn_str_len) == 0)
ndpi_set_risk(flow, NDPI_INVALID_CHARACTERS, alpn_str);
if(flow->protos.tls_quic.negotiated_alpn == NULL)
flow->protos.tls_quic.negotiated_alpn = ndpi_strdup(alpn_str);
/* Check ALPN only if not already checked (client-side) */
if(flow->protos.tls_quic.negotiated_alpn != NULL &&
flow->protos.tls_quic.advertised_alpns == NULL)
tlsCheckUncommonALPN(ndpi_struct, flow, flow->protos.tls_quic.negotiated_alpn);
alpn_str_len = ndpi_min(sizeof(ja.server.alpn), (size_t)alpn_str_len);
memcpy(ja.server.alpn, alpn_str, alpn_str_len);
if(alpn_str_len > 0)
ja.server.alpn[alpn_str_len - 1] = '\0';
/* Replace , with - as in JA3 */
for(i=0; ja.server.alpn[i] != '\0'; i++)
if(ja.server.alpn[i] == ',') ja.server.alpn[i] = '-';
} else if(extension_id == 11 /* ec_point_formats groups */) {
u_int16_t s_offset = offset+4 + 1;
#ifdef DEBUG_TLS
printf("Server TLS [EllipticCurveFormat: len=%u]\n", extension_len);
#endif
if((s_offset+extension_len-1) <= total_len) {
for(i=0; i<extension_len-1 && s_offset+i<packet->payload_packet_len; i++) {
u_int8_t s_group = packet->payload[s_offset+i];
#ifdef DEBUG_TLS
printf("Server TLS [EllipticCurveFormat: %u]\n", s_group);
#endif
if(ja.server.num_elliptic_curve_point_format < MAX_NUM_JA)
ja.server.elliptic_curve_point_format[ja.server.num_elliptic_curve_point_format++] = s_group;
else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Server TLS Invalid num elliptic %u\n", ja.server.num_elliptic_curve_point_format);
#endif
}
}
} else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Server TLS Invalid len %u vs %u\n", s_offset+extension_len, total_len);
#endif
}
}
i += 4 + extension_len, offset += 4 + extension_len;
} /* for */
/* If the CH is not available and if "supported_versions" extension is not present in the SH
(i.e. (D)TLS <= 1.2), use the version field present in the record layer */
if(flow->protos.tls_quic.ssl_version == 0)
flow->protos.tls_quic.ssl_version = tls_version;
if(ndpi_struct->cfg.tls_ja3s_fingerprint_enabled) {
u_int16_t ja_str_len;
char ja_str[JA_STR_LEN];
ndpi_MD5_CTX ctx;
u_char md5_hash[16];
ja_str_len = ndpi_snprintf(ja_str, JA_STR_LEN, "%u,", ja.server.tls_handshake_version);
for(i=0; (i<ja.server.num_ciphers) && (JA_STR_LEN > ja_str_len); i++) {
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, "%s%u", (i > 0) ? "-" : "", ja.server.cipher[i]);
if(rc <= 0) break; else ja_str_len += rc;
}
if(JA_STR_LEN > ja_str_len) {
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, ",");
if(rc > 0 && ja_str_len + rc < JA_STR_LEN) ja_str_len += rc;
}
/* ********** */
for(i=0; (i<ja.server.num_tls_extensions) && (JA_STR_LEN > ja_str_len); i++) {
int rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, "%s%u", (i > 0) ? "-" : "", ja.server.tls_extension[i]);
if(rc <= 0) break; else ja_str_len += rc;
}
#ifdef DEBUG_TLS
printf("[JA3] Server: %s \n", ja_str);
#endif
ndpi_MD5Init(&ctx);
ndpi_MD5Update(&ctx, (const unsigned char *)ja_str, strlen(ja_str));
ndpi_MD5Final(md5_hash, &ctx);
for(i=0, j=0; i<16; i++) {
int rc = ndpi_snprintf(&flow->protos.tls_quic.ja3_server[j],
sizeof(flow->protos.tls_quic.ja3_server)-j, "%02x", md5_hash[i]);
if(rc <= 0) break; else j += rc;
}
#ifdef DEBUG_TLS
printf("[JA3] Server: %s \n", flow->protos.tls_quic.ja3_server);
#endif
}
} else if(handshake_type == 0x01 /* Client Hello */) {
u_int16_t cipher_len, cipher_offset;
u_int8_t cookie_len = 0;
ja.client.num_ciphers = 0;
ja.client.num_tls_extensions = 0;
ja.client.num_elliptic_curve = 0;
ja.client.num_elliptic_curve_point_format = 0;
ja.client.num_signature_algorithms = 0;
ja.client.num_supported_versions = 0;
ja.client.signature_algorithms_str[0] = '\0';
ja.client.alpn[0] = '\0';
flow->protos.tls_quic.ssl_version = ja.client.tls_handshake_version = tls_version;
if(flow->protos.tls_quic.ssl_version < 0x0303) /* < TLSv1.2 */ {
char str[32], buf[32];
u_int8_t unknown_tls_version;
snprintf(str, sizeof(str), "%s", ndpi_ssl_version2str(buf, sizeof(buf),
flow->protos.tls_quic.ssl_version,
&unknown_tls_version));
ndpi_set_risk(flow, NDPI_TLS_OBSOLETE_VERSION, str);
}
if((session_id_len+base_offset+3) > packet->payload_packet_len)
return(0); /* Not found */
if(!is_dtls) {
cipher_len = packet->payload[session_id_len+base_offset+2] + (packet->payload[session_id_len+base_offset+1] << 8);
cipher_offset = base_offset + session_id_len + 3;
} else {
cookie_len = packet->payload[base_offset+session_id_len+1];
#ifdef DEBUG_TLS
printf("[JA3] Client: DTLS cookie len %d\n", cookie_len);
#endif
if((session_id_len+base_offset+cookie_len+4) > packet->payload_packet_len)
return(0); /* Not found */
cipher_len = ntohs(*((u_int16_t*)&packet->payload[base_offset+session_id_len+cookie_len+2]));
cipher_offset = base_offset + session_id_len + cookie_len + 4;
}
#ifdef DEBUG_TLS
printf("Client TLS [client cipher_len: %u][tls_version: 0x%04X]\n", cipher_len, tls_version);
#endif
if((cipher_offset+cipher_len) <= total_len - 1) { /* -1 because variable "id" is a u_int16_t */
u_int8_t safari_ciphers = 0, chrome_ciphers = 0, this_is_not_safari = 0, looks_like_safari_on_big_sur = 0;
for(i=0; i<cipher_len;) {
u_int16_t *id = (u_int16_t*)&packet->payload[cipher_offset+i];
u_int16_t cipher_id = ntohs(*id);
if(cipher_offset+i+1 < packet->payload_packet_len &&
((packet->payload[cipher_offset+i] != packet->payload[cipher_offset+i+1]) ||
((packet->payload[cipher_offset+i] & 0xF) != 0xA)) /* Skip Grease */) {
/*
Skip GREASE [https://tools.ietf.org/id/draft-ietf-tls-grease-01.html]
https://engineering.salesforce.com/tls-fingerprinting-with-ja3-and-ja3s-247362855967
*/
#if defined(DEBUG_TLS) || defined(DEBUG_HEURISTIC)
printf("Client TLS [non-GREASE cipher suite: %u/0x%04X] [%d/%u]\n", cipher_id, cipher_id, i, cipher_len);
#endif
if(ja.client.num_ciphers < MAX_NUM_JA)
ja.client.cipher[ja.client.num_ciphers++] = cipher_id;
else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid cipher %u\n", ja.client.num_ciphers);
#endif
}
#if defined(DEBUG_TLS) || defined(DEBUG_HEURISTIC)
printf("Client TLS [cipher suite: %u/0x%04X] [%d/%u]\n", cipher_id, cipher_id, i, cipher_len);
#endif
switch(cipher_id) {
case TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256:
case TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384:
safari_ciphers++;
break;
case TLS_AES_128_GCM_SHA256:
case TLS_AES_256_GCM_SHA384:
case TLS_CHACHA20_POLY1305_SHA256:
chrome_ciphers++;
break;
case TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256:
case TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384:
case TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256:
case TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256:
case TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA:
case TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:
case TLS_RSA_WITH_AES_128_CBC_SHA:
case TLS_RSA_WITH_AES_256_CBC_SHA:
case TLS_RSA_WITH_AES_128_GCM_SHA256:
case TLS_RSA_WITH_AES_256_GCM_SHA384:
safari_ciphers++, chrome_ciphers++;
break;
case TLS_RSA_WITH_3DES_EDE_CBC_SHA:
looks_like_safari_on_big_sur = 1;
break;
}
} else {
#if defined(DEBUG_TLS) || defined(DEBUG_HEURISTIC)
printf("Client TLS [GREASE cipher suite: %u/0x%04X] [%d/%u]\n", cipher_id, cipher_id, i, cipher_len);
#endif
this_is_not_safari = 1; /* NOTE: BugSur and up have grease support */
}
i += 2;
} /* for */
/* NOTE:
we do not check for duplicates as with signatures because
this is time consuming and we want to avoid overhead whem possible
*/
if(this_is_not_safari)
flow->protos.tls_quic.browser_heuristics.is_safari_tls = 0;
else if((safari_ciphers == 12) || (this_is_not_safari && looks_like_safari_on_big_sur))
flow->protos.tls_quic.browser_heuristics.is_safari_tls = 1;
if(chrome_ciphers == 13)
flow->protos.tls_quic.browser_heuristics.is_chrome_tls = 1;
/* Note that both Safari and Chrome can overlap */
#ifdef DEBUG_HEURISTIC
printf("[CIPHERS] [is_chrome_tls: %u (%u)][is_safari_tls: %u (%u)][this_is_not_safari: %u]\n",
flow->protos.tls_quic.browser_heuristics.is_chrome_tls,
chrome_ciphers,
flow->protos.tls_quic.browser_heuristics.is_safari_tls,
safari_ciphers,
this_is_not_safari);
#endif
} else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid len %u vs %u\n", (cipher_offset+cipher_len), total_len);
#endif
}
offset = base_offset + session_id_len + cookie_len + cipher_len + 2;
offset += (!is_dtls) ? 1 : 2;
if(offset < total_len) {
u_int16_t compression_len;
u_int16_t extensions_len;
compression_len = packet->payload[offset];
offset++;
#ifdef DEBUG_TLS
printf("Client TLS [compression_len: %u]\n", compression_len);
#endif
// offset += compression_len + 3;
offset += compression_len;
if(offset+1 < total_len) {
extensions_len = ntohs(*((u_int16_t*)&packet->payload[offset]));
offset += 2;
#ifdef DEBUG_TLS
printf("Client TLS [extensions_len: %u]\n", extensions_len);
#endif
if((extensions_len+offset) <= total_len) {
/* Move to the first extension
Type is u_int to avoid possible overflow on extension_len addition */
u_int extension_offset = 0;
while(extension_offset < extensions_len &&
offset+extension_offset+4 <= total_len) {
u_int16_t extension_id, extension_len, extn_off = offset+extension_offset;
extension_id = ntohs(*((u_int16_t*)&packet->payload[offset+extension_offset]));
extension_offset += 2;
extension_len = ntohs(*((u_int16_t*)&packet->payload[offset+extension_offset]));
extension_offset += 2;
#ifdef DEBUG_TLS
printf("Client TLS [extension_id: %u][extension_len: %u]\n", extension_id, extension_len);
#endif
checkExtensions(ndpi_struct, flow, is_dtls,
extension_id, extension_len, offset + extension_offset);
if(offset + 4 + extension_len > total_len) {
#ifdef DEBUG_TLS
printf("[TLS] extension length %u too long (%u, offset %u)\n",
extension_len, total_len, offset);
#endif
break;
}
if((extension_id == 0) || (packet->payload[extn_off] != packet->payload[extn_off+1]) ||
((packet->payload[extn_off] & 0xF) != 0xA)) {
/* Skip GREASE */
if(ja.client.num_tls_extensions < MAX_NUM_JA)
ja.client.tls_extension[ja.client.num_tls_extensions++] = extension_id;
else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid extensions %u\n", ja.client.num_tls_extensions);
#endif
}
}
if(extension_id == 0 /* server name */) {
u_int16_t len;
#ifdef DEBUG_TLS
printf("[TLS] Extensions: found server name\n");
#endif
if((offset+extension_offset+4) < packet->payload_packet_len) {
len = (packet->payload[offset+extension_offset+3] << 8) + packet->payload[offset+extension_offset+4];
if((offset+extension_offset+5+len) <= packet->payload_packet_len) {
char *sni = ndpi_hostname_sni_set(flow, &packet->payload[offset+extension_offset+5], len, NDPI_HOSTNAME_NORM_ALL);
int sni_len = strlen(sni);
#ifdef DEBUG_TLS
printf("[TLS] SNI: [%s]\n", sni);
#endif
if(ndpi_is_valid_hostname((char *)&packet->payload[offset+extension_offset+5], len) == 0) {
ndpi_set_risk(flow, NDPI_INVALID_CHARACTERS, sni);
/* This looks like an attack */
ndpi_set_risk(flow, NDPI_POSSIBLE_EXPLOIT, "Invalid chars found in SNI: exploit or misconfiguration?");
}
if(!is_quic) {
if(ndpi_struct->cfg.tls_subclassification_enabled &&
ndpi_match_hostname_protocol(ndpi_struct, flow, __get_master(ndpi_struct, flow), sni, sni_len))
flow->protos.tls_quic.subprotocol_detected = 1;
} else {
if(ndpi_struct->cfg.quic_subclassification_enabled &&
ndpi_match_hostname_protocol(ndpi_struct, flow, NDPI_PROTOCOL_QUIC, sni, sni_len))
flow->protos.tls_quic.subprotocol_detected = 1;
}
if((flow->protos.tls_quic.subprotocol_detected == 0)
&& (check_sni_is_numeric_ip(sni) == 1)) {
ndpi_set_risk(flow, NDPI_NUMERIC_IP_HOST, sni);
}
if(ndpi_check_dga_name(ndpi_struct, flow, sni, 1, 0)) {
#ifdef DEBUG_TLS
printf("[TLS] SNI: (DGA) [%s]\n", sni);
#endif
if((sni_len >= 4)
/* Check if it ends in .com or .net */
&& ((strcmp(&sni[sni_len-4], ".com") == 0) || (strcmp(&sni[sni_len-4], ".net") == 0))
&& (strncmp(sni, "www.", 4) == 0)) /* Not starting with www.... */
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_TOR, __get_master(ndpi_struct, flow), NDPI_CONFIDENCE_DPI);
} else {
#ifdef DEBUG_TLS
printf("[TLS] SNI: (NO DGA) [%s]\n", sni);
#endif
}
} else {
#ifdef DEBUG_TLS
printf("[TLS] Extensions server len too short: %u vs %u\n",
offset+extension_offset+5+len,
packet->payload_packet_len);
#endif
}
}
} else if(extension_id == 10 /* supported groups */) {
u_int16_t s_offset = offset+extension_offset + 2;
#ifdef DEBUG_TLS
printf("Client TLS [EllipticCurveGroups: len=%u]\n", extension_len);
#endif
if((s_offset+extension_len-2) <= total_len) {
for(i=0; i<(u_int32_t)extension_len-2 && s_offset + i + 1 < total_len; i += 2) {
u_int16_t s_group = ntohs(*((u_int16_t*)&packet->payload[s_offset+i]));
#ifdef DEBUG_TLS
printf("Client TLS [EllipticCurve: %u/0x%04X]\n", s_group, s_group);
#endif
if((s_group == 0) || (packet->payload[s_offset+i] != packet->payload[s_offset+i+1])
|| ((packet->payload[s_offset+i] & 0xF) != 0xA)) {
/* Skip GREASE */
if(ja.client.num_elliptic_curve < MAX_NUM_JA)
ja.client.elliptic_curve[ja.client.num_elliptic_curve++] = s_group;
else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid num elliptic %u\n", ja.client.num_elliptic_curve);
#endif
}
}
}
} else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid len %u vs %u\n", (s_offset+extension_len-1), total_len);
#endif
}
} else if(extension_id == 11 /* ec_point_formats groups */) {
u_int16_t s_offset = offset+extension_offset + 1;
#ifdef DEBUG_TLS
printf("Client TLS [EllipticCurveFormat: len=%u]\n", extension_len);
#endif
if((s_offset+extension_len-1) <= total_len) {
for(i=0; i<(u_int32_t)extension_len-1 && s_offset+i < total_len; i++) {
u_int8_t s_group = packet->payload[s_offset+i];
#ifdef DEBUG_TLS
printf("Client TLS [EllipticCurveFormat: %u]\n", s_group);
#endif
if(ja.client.num_elliptic_curve_point_format < MAX_NUM_JA)
ja.client.elliptic_curve_point_format[ja.client.num_elliptic_curve_point_format++] = s_group;
else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid num elliptic %u\n", ja.client.num_elliptic_curve_point_format);
#endif
}
}
} else {
invalid_ja = 1;
#ifdef DEBUG_TLS
printf("Client TLS Invalid len %u vs %u\n", s_offset+extension_len, total_len);
#endif
}
} else if(extension_id == 13 /* signature algorithms */ &&
offset+extension_offset+1 < total_len) {
int s_offset = offset+extension_offset, safari_signature_algorithms = 0,
chrome_signature_algorithms = 0, duplicate_found = 0, last_signature = 0, id;
u_int16_t tot_signature_algorithms_len = ntohs(*((u_int16_t*)&packet->payload[s_offset]));
#ifdef DEBUG_TLS
printf("Client TLS [SIGNATURE_ALGORITHMS: block_len=%u/len=%u]\n", extension_len, tot_signature_algorithms_len);
#endif
s_offset += 2;
tot_signature_algorithms_len = ndpi_min((sizeof(ja.client.signature_algorithms_str) / 2) - 1, tot_signature_algorithms_len);
#ifdef TLS_HANDLE_SIGNATURE_ALGORITMS
size_t sa_size = ndpi_min(tot_signature_algorithms_len / 2, MAX_NUM_TLS_SIGNATURE_ALGORITHMS);
if (s_offset + 2 * sa_size <= packet->payload_packet_len) {
flow->protos.tls_quic.num_tls_signature_algorithms = sa_size;
memcpy(flow->protos.tls_quic.client_signature_algorithms,
&packet->payload[s_offset], 2 /* 16 bit */ * sa_size);
}
#endif
for(i=0, id=0; i<tot_signature_algorithms_len && s_offset+i+1<total_len; i += 2) {
ja.client.signature_algorithms[id++] = ntohs(*(u_int16_t*)&packet->payload[s_offset+i]);
}
ja.client.num_signature_algorithms = id;
for(i=0, id=0; i<tot_signature_algorithms_len && s_offset+i+1<total_len; i++) {
int rc = ndpi_snprintf(&ja.client.signature_algorithms_str[i*2],
sizeof(ja.client.signature_algorithms_str)-i*2,
"%02X", packet->payload[s_offset+i]);
if(rc < 0) break;
}
for(i=0; i<tot_signature_algorithms_len && s_offset + (int)i + 2 < packet->payload_packet_len; i+=2) {
u_int16_t signature_algo = (u_int16_t)ntohs(*((u_int16_t*)&packet->payload[s_offset+i]));
if(last_signature == signature_algo) {
/* Consecutive duplication */
duplicate_found = 1;
continue;
} else {
/* Check for other duplications */
u_int all_ok = 1;
for(j=0; j<tot_signature_algorithms_len; j+=2) {
if(j != i && s_offset + (int)j + 2 < packet->payload_packet_len) {
u_int16_t j_signature_algo = (u_int16_t)ntohs(*((u_int16_t*)&packet->payload[s_offset+j]));
if((signature_algo == j_signature_algo)
&& (i < j) /* Don't skip both of them */) {
#ifdef DEBUG_HEURISTIC
printf("[SIGNATURE] [TLS Signature Algorithm] Skipping duplicate 0x%04X\n", signature_algo);
#endif
duplicate_found = 1, all_ok = 0;
break;
}
}
}
if(!all_ok)
continue;
}
last_signature = signature_algo;
#ifdef DEBUG_HEURISTIC
printf("[SIGNATURE] [TLS Signature Algorithm] 0x%04X\n", signature_algo);
#endif
switch(signature_algo) {
case ECDSA_SECP521R1_SHA512:
flow->protos.tls_quic.browser_heuristics.is_firefox_tls = 1;
break;
case ECDSA_SECP256R1_SHA256:
case ECDSA_SECP384R1_SHA384:
case RSA_PKCS1_SHA256:
case RSA_PKCS1_SHA384:
case RSA_PKCS1_SHA512:
case RSA_PSS_RSAE_SHA256:
case RSA_PSS_RSAE_SHA384:
case RSA_PSS_RSAE_SHA512:
chrome_signature_algorithms++, safari_signature_algorithms++;
#ifdef DEBUG_HEURISTIC
printf("[SIGNATURE] [Chrome/Safari] Found 0x%04X [chrome: %u][safari: %u]\n",
signature_algo, chrome_signature_algorithms, safari_signature_algorithms);
#endif
break;
}
}
#ifdef DEBUG_HEURISTIC
printf("[SIGNATURE] [safari_signature_algorithms: %u][chrome_signature_algorithms: %u]\n",
safari_signature_algorithms, chrome_signature_algorithms);
#endif
if(flow->protos.tls_quic.browser_heuristics.is_firefox_tls)
flow->protos.tls_quic.browser_heuristics.is_safari_tls = 0,
flow->protos.tls_quic.browser_heuristics.is_chrome_tls = 0;
if(safari_signature_algorithms != 8)
flow->protos.tls_quic.browser_heuristics.is_safari_tls = 0;
if((chrome_signature_algorithms != 8) || duplicate_found)
flow->protos.tls_quic.browser_heuristics.is_chrome_tls = 0;
/* Avoid Chrome and Safari overlaps, thing that cannot happen with Firefox */
if(flow->protos.tls_quic.browser_heuristics.is_safari_tls)
flow->protos.tls_quic.browser_heuristics.is_chrome_tls = 0;
if((flow->protos.tls_quic.browser_heuristics.is_chrome_tls == 0)
&& duplicate_found)
flow->protos.tls_quic.browser_heuristics.is_safari_tls = 1; /* Safari */
#ifdef DEBUG_HEURISTIC
printf("[SIGNATURE] [is_firefox_tls: %u][is_chrome_tls: %u][is_safari_tls: %u][duplicate_found: %u]\n",
flow->protos.tls_quic.browser_heuristics.is_firefox_tls,
flow->protos.tls_quic.browser_heuristics.is_chrome_tls,
flow->protos.tls_quic.browser_heuristics.is_safari_tls,
duplicate_found);
#endif
if(i > 0 && i >= tot_signature_algorithms_len) {
ja.client.signature_algorithms_str[i*2 - 1] = '\0';
} else {
ja.client.signature_algorithms_str[i*2] = '\0';
}
#ifdef DEBUG_TLS
printf("Client TLS [SIGNATURE_ALGORITHMS: %s]\n", ja.client.signature_algorithms_str);
#endif
} else if(extension_id == 14 /* use_srtp */) {
/* This is likely a werbrtc flow */
if(flow->stun.maybe_dtls || flow->detected_protocol_stack[0] == NDPI_PROTOCOL_DTLS)
flow->protos.tls_quic.webrtc = 1;
#ifdef DEBUG_TLS
printf("Client TLS: use_srtp\n");
#endif
} else if(extension_id == 16 /* application_layer_protocol_negotiation */ &&
offset+extension_offset+1 < total_len) {
u_int16_t s_offset = offset+extension_offset;
u_int16_t tot_alpn_len = ntohs(*((u_int16_t*)&packet->payload[s_offset]));
char alpn_str[256];
u_int16_t alpn_str_len = 0, i;
#ifdef DEBUG_TLS
printf("Client TLS [ALPN: block_len=%u/len=%u]\n", extension_len, tot_alpn_len);
#endif
s_offset += 2;
tot_alpn_len += s_offset;
while(s_offset < tot_alpn_len && s_offset < total_len) {
u_int8_t alpn_i, alpn_len = packet->payload[s_offset++];
if((s_offset + alpn_len) <= tot_alpn_len &&
(s_offset + alpn_len) <= total_len) {
#ifdef DEBUG_TLS
printf("Client TLS [ALPN: %u]\n", alpn_len);
#endif
if(((uint32_t)alpn_str_len+alpn_len+1) < (sizeof(alpn_str)-1)) {
if(alpn_str_len > 0) {
alpn_str[alpn_str_len] = ',';
alpn_str_len++;
}
for(alpn_i=0; alpn_i<alpn_len; alpn_i++)
alpn_str[alpn_str_len+alpn_i] = packet->payload[s_offset+alpn_i];
s_offset += alpn_len, alpn_str_len += alpn_len;;
} else
break;
} else
break;
} /* while */
alpn_str[alpn_str_len] = '\0';
#ifdef DEBUG_TLS
printf("Client TLS [ALPN: %s][len: %u]\n", alpn_str, alpn_str_len);
#endif
if(flow->protos.tls_quic.advertised_alpns == NULL) {
flow->protos.tls_quic.advertised_alpns = ndpi_strdup(alpn_str);
if(flow->protos.tls_quic.advertised_alpns) {
tlsCheckUncommonALPN(ndpi_struct, flow, flow->protos.tls_quic.advertised_alpns);
/* Without SNI matching we can try to sub-classify the flow via ALPN.
Note that this happens only on very rare cases, not the common ones
("h2", "http/1.1", ...). Usefull for asymmetric traffic */
if(!flow->protos.tls_quic.subprotocol_detected) {
if((is_quic && ndpi_struct->cfg.quic_subclassification_enabled) ||
(!is_quic && ndpi_struct->cfg.tls_subclassification_enabled))
tls_subclassify_by_alpn(ndpi_struct, flow);
}
}
}
alpn_str_len = ndpi_min(sizeof(ja.client.alpn), (size_t)alpn_str_len);
memcpy(ja.client.alpn, alpn_str, alpn_str_len);
if(alpn_str_len > 0)
ja.client.alpn[alpn_str_len - 1] = '\0';
/* Replace , with - as in JA3 */
for(i=0; ja.client.alpn[i] != '\0'; i++)
if(ja.client.alpn[i] == ',') ja.client.alpn[i] = '-';
} else if(extension_id == 43 /* supported versions */ &&
offset+extension_offset < total_len) {
u_int16_t s_offset = offset+extension_offset;
u_int8_t version_len = packet->payload[s_offset];
char version_str[256];
char buf_ver_tmp[16];
size_t version_str_len = 0;
version_str[0] = 0;
#ifdef DEBUG_TLS
printf("Client TLS [TLS version len: %u]\n", version_len);
#endif
if(version_len == (extension_len-1)) {
u_int8_t j;
s_offset++;
// careful not to overflow and loop forever with u_int8_t
for(j=0; j+1<version_len && s_offset + j + 1 < packet->payload_packet_len; j += 2) {
u_int16_t tls_version = ntohs(*((u_int16_t*)&packet->payload[s_offset+j]));
u_int8_t unknown_tls_version;
#ifdef DEBUG_TLS
printf("Client TLS [TLS version: %s/0x%04X]\n",
ndpi_ssl_version2str(buf_ver_tmp, sizeof(buf_ver_tmp), tls_version, &unknown_tls_version), tls_version);
#endif
if((version_str_len+8) < sizeof(version_str)) {
int rc = ndpi_snprintf(&version_str[version_str_len],
sizeof(version_str) - version_str_len, "%s%s",
(version_str_len > 0) ? "," : "",
ndpi_ssl_version2str(buf_ver_tmp, sizeof(buf_ver_tmp), tls_version, &unknown_tls_version));
if(rc <= 0)
break;
else
version_str_len += rc;
if(ja.client.num_supported_versions < MAX_NUM_JA)
ja.client.supported_versions[ja.client.num_supported_versions++] = tls_version;
}
}
#ifdef DEBUG_TLS
printf("Client TLS [SUPPORTED_VERSIONS: %s]\n", version_str);
#endif
if(flow->protos.tls_quic.tls_supported_versions == NULL)
flow->protos.tls_quic.tls_supported_versions = ndpi_strdup(version_str);
}
} else if(extension_id == 65486 /* encrypted server name */ &&
offset+extension_offset+1 < total_len) {
/*
- https://tools.ietf.org/html/draft-ietf-tls-esni-06
- https://blog.cloudflare.com/encrypted-sni/
*/
int e_offset = offset+extension_offset;
int e_sni_len;
int initial_offset = e_offset;
u_int16_t cipher_suite = ntohs(*((u_int16_t*)&packet->payload[e_offset]));
flow->protos.tls_quic.encrypted_sni.cipher_suite = cipher_suite;
e_offset += 2; /* Cipher suite len */
/* Key Share Entry */
e_offset += 2; /* Group */
if(e_offset + 2 < packet->payload_packet_len) {
e_offset += ntohs(*((u_int16_t*)&packet->payload[e_offset])) + 2; /* Lenght */
if((e_offset+4) < packet->payload_packet_len) {
/* Record Digest */
e_offset += ntohs(*((u_int16_t*)&packet->payload[e_offset])) + 2; /* Lenght */
if((e_offset+4) < packet->payload_packet_len) {
e_sni_len = ntohs(*((u_int16_t*)&packet->payload[e_offset]));
e_offset += 2;
if((e_offset+e_sni_len-(int)extension_len-initial_offset) >= 0 &&
e_offset+e_sni_len < packet->payload_packet_len) {
#ifdef DEBUG_ENCRYPTED_SNI
printf("Client TLS [Encrypted Server Name len: %u]\n", e_sni_len);
#endif
if(flow->protos.tls_quic.encrypted_sni.esni == NULL) {
flow->protos.tls_quic.encrypted_sni.esni = (char*)ndpi_malloc(e_sni_len*2+1);
if(flow->protos.tls_quic.encrypted_sni.esni) {
u_int16_t off;
int i;
for(i=e_offset, off=0; i<(e_offset+e_sni_len); i++) {
int rc = sprintf(&flow->protos.tls_quic.encrypted_sni.esni[off], "%02X", packet->payload[i] & 0XFF);
if(rc <= 0) {
break;
} else
off += rc;
}
flow->protos.tls_quic.encrypted_sni.esni[off] = '\0';
}
}
}
}
}
}
} else if(extension_id == 65037 /* ECH: latest drafts */) {
#ifdef DEBUG_TLS
printf("Client TLS: ECH version 0x%x\n", extension_id);
#endif
/* Beginning with draft-08, the version is the same as the code point
for the "encrypted_client_hello" extension. */
flow->protos.tls_quic.encrypted_ch.version = extension_id;
} else if(extension_id == 65445 || /* QUIC transport parameters (drafts version) */
extension_id == 57) { /* QUIC transport parameters (final version) */
u_int16_t s_offset = offset+extension_offset;
uint16_t final_offset;
int using_var_int = is_version_with_var_int_transport_params(quic_version);
if(!using_var_int) {
if(s_offset+1 >= total_len) {
final_offset = 0; /* Force skipping extension */
} else {
u_int16_t seq_len = ntohs(*((u_int16_t*)&packet->payload[s_offset]));
s_offset += 2;
final_offset = ndpi_min(total_len, s_offset + seq_len);
}
} else {
final_offset = ndpi_min(total_len, s_offset + extension_len);
}
while(s_offset < final_offset) {
u_int64_t param_type, param_len;
if(!using_var_int) {
if(s_offset+3 >= final_offset)
break;
param_type = ntohs(*((u_int16_t*)&packet->payload[s_offset]));
param_len = ntohs(*((u_int16_t*)&packet->payload[s_offset + 2]));
s_offset += 4;
} else {
if(s_offset >= final_offset ||
(s_offset + quic_len_buffer_still_required(packet->payload[s_offset])) >= final_offset)
break;
s_offset += quic_len(&packet->payload[s_offset], ¶m_type);
if(s_offset >= final_offset ||
(s_offset + quic_len_buffer_still_required(packet->payload[s_offset])) >= final_offset)
break;
s_offset += quic_len(&packet->payload[s_offset], ¶m_len);
}
#ifdef DEBUG_TLS
printf("Client TLS [QUIC TP: Param 0x%x Len %d]\n", (int)param_type, (int)param_len);
#endif
if(s_offset+param_len > final_offset)
break;
if(param_type==0x3129) {
#ifdef DEBUG_TLS
printf("UA [%.*s]\n", (int)param_len, &packet->payload[s_offset]);
#endif
http_process_user_agent(ndpi_struct, flow, &packet->payload[s_offset], param_len);
break;
}
s_offset += param_len;
}
}
extension_offset += extension_len; /* Move to the next extension */
#ifdef DEBUG_TLS
printf("Client TLS [extension_offset/len: %u/%u]\n", extension_offset, extension_len);
#endif
} /* while */
if(!invalid_ja) {
/* Compute JA3 client */
compute_ja3c:
if(ndpi_struct->cfg.tls_ja3c_fingerprint_enabled) {
int rc;
u_int16_t ja_str_len;
char ja_str[JA_STR_LEN];
ndpi_MD5_CTX ctx;
u_char md5_hash[16];
ja_str_len = ndpi_snprintf(ja_str, JA_STR_LEN, "%u,", ja.client.tls_handshake_version);
for(i=0; i<ja.client.num_ciphers; i++) {
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, "%s%u",
(i > 0) ? "-" : "", ja.client.cipher[i]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc; else break;
}
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, ",");
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc;
/* ********** */
for(i=0; i<ja.client.num_tls_extensions; i++) {
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, "%s%u",
(i > 0) ? "-" : "", ja.client.tls_extension[i]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc; else break;
}
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, ",");
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc;
/* ********** */
for(i=0; i<ja.client.num_elliptic_curve; i++) {
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, "%s%u",
(i > 0) ? "-" : "", ja.client.elliptic_curve[i]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc; else break;
}
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, ",");
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc;
for(i=0; i<ja.client.num_elliptic_curve_point_format; i++) {
rc = ndpi_snprintf(&ja_str[ja_str_len], JA_STR_LEN-ja_str_len, "%s%u",
(i > 0) ? "-" : "", ja.client.elliptic_curve_point_format[i]);
if((rc > 0) && (ja_str_len + rc < JA_STR_LEN)) ja_str_len += rc; else break;
}
ndpi_MD5Init(&ctx);
ndpi_MD5Update(&ctx, (const unsigned char *)ja_str, strlen(ja_str));
ndpi_MD5Final(md5_hash, &ctx);
for(i=0, j=0; i<16; i++) {
rc = ndpi_snprintf(&flow->protos.tls_quic.ja3_client[j],
sizeof(flow->protos.tls_quic.ja3_client)-j, "%02x",
md5_hash[i]);
if(rc > 0) j += rc; else break;
}
#ifdef DEBUG_JA
printf("[JA3] Client: %s \n", flow->protos.tls_quic.ja3_client);
#endif
if(ndpi_struct->malicious_ja3_hashmap != NULL) {
u_int16_t rc1 = ndpi_hash_find_entry(ndpi_struct->malicious_ja3_hashmap,
flow->protos.tls_quic.ja3_client,
NDPI_ARRAY_LENGTH(flow->protos.tls_quic.ja3_client) - 1,
NULL);
if(rc1 == 0)
ndpi_set_risk(flow, NDPI_MALICIOUS_FINGERPRINT, flow->protos.tls_quic.ja3_client);
}
}
if(ndpi_struct->cfg.tls_ja4c_fingerprint_enabled) {
ndpi_compute_ja4(ndpi_struct, flow, quic_version, &ja);
}
/* End JA3/JA4 */
}
/* Before returning to the caller we need to make a final check */
if((flow->protos.tls_quic.ssl_version >= 0x0303) /* >= TLSv1.2 */
&& !flow->protos.tls_quic.webrtc
&& (flow->protos.tls_quic.advertised_alpns == NULL) /* No ALPN */) {
ndpi_set_risk(flow, NDPI_TLS_NOT_CARRYING_HTTPS, "No ALPN");
}
/* Suspicious Domain Fronting:
https://github.com/SixGenInc/Noctilucent/blob/master/docs/ */
if(flow->protos.tls_quic.encrypted_sni.esni &&
flow->host_server_name[0] != '\0') {
ndpi_set_risk(flow, NDPI_TLS_SUSPICIOUS_ESNI_USAGE, "Found ESNI w/o SNI");
}
/* Add check for missing SNI */
if(flow->host_server_name[0] == '\0'
&& (flow->protos.tls_quic.ssl_version >= 0x0302) /* TLSv1.1 */
&& !flow->protos.tls_quic.webrtc
&& (flow->protos.tls_quic.encrypted_sni.esni == NULL) /* No ESNI */
) {
/* This is a bit suspicious */
ndpi_set_risk(flow, NDPI_TLS_MISSING_SNI, "SNI should always be present");
if(flow->protos.tls_quic.advertised_alpns != NULL) {
char buf[256], *tmp, *item;
snprintf(buf, sizeof(buf), "%s", flow->protos.tls_quic.advertised_alpns);
item = strtok_r(buf, ",", &tmp);
while(item != NULL) {
if(item[0] == 'h') {
/* Example 'h2' */
ndpi_set_risk(flow, NDPI_TLS_ALPN_SNI_MISMATCH, item);
break;
} else
item = strtok_r(NULL, ",", &tmp);
}
}
}
return(2 /* Client Certificate */);
} else {
#ifdef DEBUG_TLS
printf("[TLS] Client: too short [%u vs %u]\n",
(extensions_len+offset), total_len);
#endif
}
} else if(offset == total_len) {
/* TLS does not have extensions etc */
goto compute_ja3c;
}
} else {
#ifdef DEBUG_TLS
printf("[JA3] Client: invalid length detected\n");
#endif
}
}
}
return(0); /* Not found */
}
/* **************************************** */
static void ndpi_search_tls_wrapper(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
#ifdef DEBUG_TLS
printf("==>> %s() %u [len: %u][version: %u]\n",
__FUNCTION__,
flow->guessed_protocol_id_by_ip,
packet->payload_packet_len,
flow->protos.tls_quic.ssl_version);
#endif
if(packet->udp != NULL || flow->stun.maybe_dtls)
ndpi_search_tls_udp(ndpi_struct, flow);
else
ndpi_search_tls_tcp(ndpi_struct, flow);
}
/* **************************************** */
void init_tls_dissector(struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id) {
ndpi_set_bitmask_protocol_detection("TLS", ndpi_struct, *id,
NDPI_PROTOCOL_TLS,
ndpi_search_tls_wrapper,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
/* *************************************************** */
ndpi_set_bitmask_protocol_detection("DTLS", ndpi_struct, *id,
NDPI_PROTOCOL_DTLS,
ndpi_search_tls_wrapper,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}