1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
/*
* emunids
*
* emulation based network intrusion system
*
* Markus Koetter 2007
*
* gcc -Wall -I/opt/libemu/include/ -L/opt/libemu/lib/libemu -o printall printall.c -lnids -lemu
*
*
*/
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdio.h>
#include "nids.h"
#include <pcap.h>
#include <emu/emu.h>
#include <emu/emu_shellcode.h>
#include <emu/emu_memory.h>
#define int_ntoa(x) inet_ntoa(*((struct in_addr *)&x))
struct emu *emu;
struct ip;
char *adres (struct tuple4 addr)
{
static char buf[256];
strcpy (buf, int_ntoa (addr.saddr));
sprintf (buf + strlen (buf), ":%i <-> ", addr.source);
strcat (buf, int_ntoa (addr.daddr));
sprintf (buf + strlen (buf), ":%i", addr.dest);
return buf;
}
void tcp_callback (struct tcp_stream *a_tcp, void ** this_time_not_needed)
{
// char buf[1024];
// strcpy (buf, adres (a_tcp->addr)); // we put conn params into buf
if ( a_tcp->nids_state == NIDS_JUST_EST )
{
a_tcp->client.collect++;
a_tcp->client.collect_urg++;
a_tcp->server.collect++;
a_tcp->server.collect_urg++;
// fprintf (stderr, "%s established\n", buf);
}/* else
if ( a_tcp->nids_state == NIDS_CLOSE )
{
fprintf (stderr, "%s closing\n", buf);
}else
if ( a_tcp->nids_state == NIDS_RESET )
{
fprintf (stderr, "%s reset\n", buf);
} */ else
if ( a_tcp->nids_state == NIDS_DATA )
{
struct half_stream *hlf;
char *data;
int size;
if ( a_tcp->server.count_new_urg || a_tcp->server.count_new )
{
hlf = &a_tcp->server;
}else
if ( a_tcp->client.count_new_urg || a_tcp->client.count_new )
{
hlf = &a_tcp->client;
}else
{
return;
}
size = hlf->count - hlf->offset;
data = hlf->data;
// printf("size is %i\n", size);
// printf("count %i offset %i size %i\n",hlf->count, hlf->offset, size);
if ( emu_shellcode_test(emu, (uint8_t *)data, size) >= 0 )
{
fprintf(stderr, "suspecting shellcode in connection %s\n", adres(a_tcp->addr));
}
if (size > 2048)
nids_discard(a_tcp, abs(2048-size));
emu_memory_clear(emu_memory_get(emu));
}
return ;
}
void xlog(int type, int err, struct ip *iph, void *data)
{
char *nids_warnings[] = {
"Murphy - you never should see this message !",
"Oversized IP packet",
"Invalid IP fragment list: fragment over size",
"Overlapping IP fragments",
"Invalid IP header",
"Source routed IP frame",
"Max number of TCP streams reached",
"Invalid TCP header",
"Too much data in TCP receive queue",
"Invalid TCP flags"
};
if (type != NIDS_WARN_SCAN)
{
printf("%s\n", nids_warnings[err]);
}
}
int main (int argc, const char *argv[])
{
if (argc == 1)
{
printf("useage %s <device>\n", argv[0]);
return -1;
}else
{
printf("listening on device %s\n", argv[1]);
}
emu = emu_new();
nids_params.device = strdup(argv[1]);;
nids_params.syslog = xlog;
if ( !nids_init () )
{
fprintf(stderr,"%s\n",nids_errbuf);
exit(1);
}
// disable checksumming as host may calculate the checksum on the nic in hardware
struct nids_chksum_ctl disable_checksums;
disable_checksums.netaddr = 0;
disable_checksums.mask = 0;
disable_checksums.action = NIDS_DONT_CHKSUM;
nids_register_chksum_ctl(&disable_checksums,1);
nids_register_tcp (tcp_callback);
nids_run ();
emu_free(emu);
return 0;
}
|
