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ndpireader: fix detection of DoH traffic based on packet distributions #2045

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Jul 14, 2023
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ndpireader: fix detection of DoH traffic based on packet distributions #2045

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60 changes: 36 additions & 24 deletions example/ndpiReader.c
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Original file line number Diff line number Diff line change
Expand Up @@ -269,33 +269,37 @@ FILE *trace = NULL;

#define NUM_DOH_BINS 2

struct ndpi_bin doh_ndpi_bins[NUM_DOH_BINS];
static struct ndpi_bin doh_ndpi_bins[NUM_DOH_BINS];

u_int8_t doh_centroids[NUM_DOH_BINS][PLEN_NUM_BINS] = {
static u_int8_t doh_centroids[NUM_DOH_BINS][PLEN_NUM_BINS] = {
{ 23,25,3,0,26,0,0,0,0,0,0,0,0,0,2,0,0,15,3,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 },
{ 35,30,21,0,0,0,2,4,0,0,5,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
};

float doh_max_distance = 35.5;
static float doh_max_distance = 35.5;

void init_doh_bins() {
static void init_doh_bins() {
u_int i;

for(i=0; i<NUM_DOH_BINS; i++) {
ndpi_init_bin(&doh_ndpi_bins[i], ndpi_bin_family8, PLEN_NUM_BINS);
ndpi_free_bin(&doh_ndpi_bins[i]); /* Hack: we use static bins (see below), so we need to free the dynamic ones just allocated */
doh_ndpi_bins[i].u.bins8 = doh_centroids[i];
}
}

/* *********************************************** */

u_int check_bin_doh_similarity(struct ndpi_bin *bin, float *similarity) {
static u_int check_bin_doh_similarity(struct ndpi_bin *bin, float *similarity) {
u_int i;
float lowest_similarity = 9999999999.0f;

for(i=0; i<NUM_DOH_BINS; i++) {
*similarity = ndpi_bin_similarity(&doh_ndpi_bins[i], bin, 0, 0);

if(*similarity < 0) /* Error */
return(0);

if(*similarity <= doh_max_distance)
return(1);

Expand Down Expand Up @@ -3402,7 +3406,7 @@ static void printFlowsStats() {

ndpi_cluster_bins(bins, num_flow_bins, num_bin_clusters, cluster_ids, centroids);

printf("\n"
fprintf(out, "\n"
"\tBin clusters\n"
"\t------------\n");

Expand All @@ -3416,23 +3420,23 @@ static void printFlowsStats() {
if(cluster_ids[i] != j) continue;

if(num_printed == 0) {
printf("\tCluster %u [", j);
fprintf(out, "\tCluster %u [", j);
print_bin(out, NULL, &centroids[j]);
printf("]\n");
fprintf(out, "]\n");
}

printf("\t%u\t%-10s\t%s:%u <-> %s:%u\t[",
i,
ndpi_protocol2name(ndpi_thread_info[0].workflow->ndpi_struct,
all_flows[i].flow->detected_protocol, buf, sizeof(buf)),
all_flows[i].flow->src_name,
ntohs(all_flows[i].flow->src_port),
all_flows[i].flow->dst_name,
ntohs(all_flows[i].flow->dst_port));
fprintf(out, "\t%u\t%-10s\t%s:%u <-> %s:%u\t[",
i,
ndpi_protocol2name(ndpi_thread_info[0].workflow->ndpi_struct,
all_flows[i].flow->detected_protocol, buf, sizeof(buf)),
all_flows[i].flow->src_name,
ntohs(all_flows[i].flow->src_port),
all_flows[i].flow->dst_name,
ntohs(all_flows[i].flow->dst_port));

print_bin(out, NULL, &bins[i]);
printf("][similarity: %f]",
(similarity = ndpi_bin_similarity(&centroids[j], &bins[i], 0, 0)));
fprintf(out, "][similarity: %f]",
(similarity = ndpi_bin_similarity(&centroids[j], &bins[i], 0, 0)));

if(all_flows[i].flow->host_server_name[0] != '\0')
fprintf(out, "[%s]", all_flows[i].flow->host_server_name);
Expand All @@ -3445,23 +3449,23 @@ static void printFlowsStats() {
&& all_flows[i].flow->ssh_tls.advertised_alpns /* ALPN */
) {
if(check_bin_doh_similarity(&bins[i], &s))
printf("[DoH (%f distance)]", s);
fprintf(out, "[DoH (%f distance)]", s);
else
printf("[NO DoH (%f distance)]", s);
fprintf(out, "[NO DoH (%f distance)]", s);
} else {
if(all_flows[i].flow->ssh_tls.advertised_alpns == NULL)
printf("[NO DoH check: missing ALPN]");
fprintf(out, "[NO DoH check: missing ALPN]");
}
}

printf("\n");
fprintf(out, "\n");
num_printed++;
if(similarity > max_similarity) max_similarity = similarity;
}

if(num_printed) {
printf("\tMax similarity: %f\n", max_similarity);
printf("\n");
fprintf(out, "\tMax similarity: %f\n", max_similarity);
fprintf(out, "\n");
}
}

Expand Down Expand Up @@ -5368,6 +5372,14 @@ int main(int argc, char **argv) {
exit(0);
}

if(enable_doh_dot_detection) {
init_doh_bins();
/* Clusters are not really used in DoH/DoT detection, but because of how
the code has been written, we need to enable also clustering feature */
if(num_bin_clusters == 0)
num_bin_clusters = 1;
}

if(!quiet_mode) {
printf("\n-----------------------------------------------------------\n"
"* NOTE: This is demo app to show *some* nDPI features.\n"
Expand Down
Binary file added tests/cfgs/default/pcap/doh.pcapng
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30 changes: 30 additions & 0 deletions tests/cfgs/default/result/doh.pcapng.out
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
Guessed flow protos: 0

DPI Packets (TCP): 6 (6.00 pkts/flow)
Confidence DPI : 1 (flows)
Num dissector calls: 1 (1.00 diss/flow)
LRU cache ookla: 0/0/0 (insert/search/found)
LRU cache bittorrent: 0/0/0 (insert/search/found)
LRU cache zoom: 0/0/0 (insert/search/found)
LRU cache stun: 0/0/0 (insert/search/found)
LRU cache tls_cert: 0/2/0 (insert/search/found)
LRU cache mining: 0/0/0 (insert/search/found)
LRU cache msteams: 0/0/0 (insert/search/found)
LRU cache stun_zoom: 0/0/0 (insert/search/found)
Automa host: 0/0 (search/found)
Automa domain: 0/0 (search/found)
Automa tls cert: 0/0 (search/found)
Automa risk mask: 0/0 (search/found)
Automa common alpns: 2/2 (search/found)
Patricia risk mask: 2/0 (search/found)
Patricia risk: 0/0 (search/found)
Patricia protocols: 2/0 (search/found)

TLS 120 14592 1

JA3 Host Stats:
IP Address # JA3C
1 192.168.1.253 1


1 TCP 192.168.1.253:35996 <-> 1.1.1.1:443 [proto: 91/TLS][IP: 0/Unknown][Encrypted][Confidence: DPI][DPI packets: 6][cat: Web/5][61 pkts/5381 bytes <-> 59 pkts/9211 bytes][Goodput ratio: 35/63][122.79 sec][(Advertised) ALPNs: h2;http/1.1][TLS Supported Versions: TLSv1.3;TLSv1.2;TLSv1.1;TLSv1][bytes ratio: -0.262 (Download)][IAT c2s/s2c min/avg/max/stddev: 0/0 1965/1934 15360/15360 4993/4853][Pkt Len c2s/s2c min/avg/max/stddev: 60/60 88/156 315/1514 41/267][Risk: ** Missing SNI TLS Extn **][Risk Score: 50][TLSv1.3][JA3C: 7c1e207beb00684bbbe144f1b0abe1d5][JA3S: d75f9129bb5d05492a65ff78e081bcb2][Firefox][Cipher: TLS_CHACHA20_POLY1305_SHA256][Plen Bins: 22,26,24,1,1,7,5,5,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0]
1 change: 1 addition & 0 deletions tests/cfgs/enable_doh_heuristic/config.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
-D
1 change: 1 addition & 0 deletions tests/cfgs/enable_doh_heuristic/pcap/doh.pcapng
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@@ -0,0 +1 @@
../../default/pcap/doh.pcapng
37 changes: 37 additions & 0 deletions tests/cfgs/enable_doh_heuristic/result/doh.pcapng.out
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Original file line number Diff line number Diff line change
@@ -0,0 +1,37 @@
Guessed flow protos: 0

DPI Packets (TCP): 24 (24.00 pkts/flow)
Confidence DPI : 1 (flows)
Num dissector calls: 1 (1.00 diss/flow)
LRU cache ookla: 0/0/0 (insert/search/found)
LRU cache bittorrent: 0/0/0 (insert/search/found)
LRU cache zoom: 0/0/0 (insert/search/found)
LRU cache stun: 0/0/0 (insert/search/found)
LRU cache tls_cert: 0/2/0 (insert/search/found)
LRU cache mining: 0/0/0 (insert/search/found)
LRU cache msteams: 0/0/0 (insert/search/found)
LRU cache stun_zoom: 0/0/0 (insert/search/found)
Automa host: 0/0 (search/found)
Automa domain: 0/0 (search/found)
Automa tls cert: 0/0 (search/found)
Automa risk mask: 0/0 (search/found)
Automa common alpns: 2/2 (search/found)
Patricia risk mask: 2/0 (search/found)
Patricia risk: 0/0 (search/found)
Patricia protocols: 2/0 (search/found)

TLS 120 14592 1

JA3 Host Stats:
IP Address # JA3C
1 192.168.1.253 1


1 TCP 192.168.1.253:35996 <-> 1.1.1.1:443 [proto: 91/TLS][IP: 0/Unknown][Encrypted][Confidence: DPI][DPI packets: 24][cat: Web/5][61 pkts/5381 bytes <-> 59 pkts/9211 bytes][Goodput ratio: 35/63][122.79 sec][(Advertised) ALPNs: h2;http/1.1][TLS Supported Versions: TLSv1.3;TLSv1.2;TLSv1.1;TLSv1][bytes ratio: -0.262 (Download)][IAT c2s/s2c min/avg/max/stddev: 0/0 1965/1934 15360/15360 4993/4853][Pkt Len c2s/s2c min/avg/max/stddev: 60/60 88/156 315/1514 41/267][Risk: ** Missing SNI TLS Extn **][Risk Score: 50][TLSv1.3][JA3C: 7c1e207beb00684bbbe144f1b0abe1d5][JA3S: d75f9129bb5d05492a65ff78e081bcb2][Firefox][Cipher: TLS_CHACHA20_POLY1305_SHA256][Plen Bins: 24,32,24,0,1,7,3,5,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]

Bin clusters
------------
Cluster 0 [24;32;24;0;1;7;3;5;0;0;1;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0]
0 TLS 192.168.1.253:35996 <-> 1.1.1.1:443 [24;32;24;0;1;7;3;5;0;0;1;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0;0][similarity: 0.000000][DoH (14.247807 distance)]
Max similarity: 0.000000

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