forked from nmap/nmap
-
Notifications
You must be signed in to change notification settings - Fork 0
/
idle_scan.cc
1419 lines (1239 loc) · 59.2 KB
/
idle_scan.cc
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
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/***************************************************************************
* idle_scan.cc -- Includes the function specific to "Idle Scan" support *
* (-sI). This is an extraordinarily cool scan type that can allow for *
* completely blind scanning (eg no packets sent to the target from your *
* own IP address) and can also be used to penetrate firewalls and scope *
* out router ACLs. This is one of the "advanced" scans meant for *
* experienced Nmap users. *
* *
***********************IMPORTANT NMAP LICENSE TERMS************************
* *
* The Nmap Security Scanner is (C) 1996-2022 Nmap Software LLC ("The Nmap *
* Project"). Nmap is also a registered trademark of the Nmap Project. *
* *
* This program is distributed under the terms of the Nmap Public Source *
* License (NPSL). The exact license text applying to a particular Nmap *
* release or source code control revision is contained in the LICENSE *
* file distributed with that version of Nmap or source code control *
* revision. More Nmap copyright/legal information is available from *
* https://nmap.org/book/man-legal.html, and further information on the *
* NPSL license itself can be found at https://nmap.org/npsl/ . This *
* header summarizes some key points from the Nmap license, but is no *
* substitute for the actual license text. *
* *
* Nmap is generally free for end users to download and use themselves, *
* including commercial use. It is available from https://nmap.org. *
* *
* The Nmap license generally prohibits companies from using and *
* redistributing Nmap in commercial products, but we sell a special Nmap *
* OEM Edition with a more permissive license and special features for *
* this purpose. See https://nmap.org/oem/ *
* *
* If you have received a written Nmap license agreement or contract *
* stating terms other than these (such as an Nmap OEM license), you may *
* choose to use and redistribute Nmap under those terms instead. *
* *
* The official Nmap Windows builds include the Npcap software *
* (https://npcap.com) for packet capture and transmission. It is under *
* separate license terms which forbid redistribution without special *
* permission. So the official Nmap Windows builds may not be *
* redistributed without special permission (such as an Nmap OEM *
* license). *
* *
* Source is provided to this software because we believe users have a *
* right to know exactly what a program is going to do before they run it. *
* This also allows you to audit the software for security holes. *
* *
* Source code also allows you to port Nmap to new platforms, fix bugs, *
* and add new features. You are highly encouraged to submit your *
* changes as a Github PR or by email to the dev@nmap.org mailing list *
* for possible incorporation into the main distribution. Unless you *
* specify otherwise, it is understood that you are offering us very *
* broad rights to use your submissions as described in the Nmap Public *
* Source License Contributor Agreement. This is important because we *
* fund the project by selling licenses with various terms, and also *
* because the inability to relicense code has caused devastating *
* problems for other Free Software projects (such as KDE and NASM). *
* *
* The free version of Nmap 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. Warranties, *
* indemnification and commercial support are all available through the *
* Npcap OEM program--see https://nmap.org/oem/ *
* *
***************************************************************************/
/* $Id$ */
/* IPv6 fragment ID sequence algorithms. http://seclists.org/nmap-dev/2013/q3/369.
Android 4.1 (Linux 3.0.15) | Per host, incremental (1)
FreeBSD 7.4 | Random
FreeBSD 9.1 | Random
iOS 6.1.2 | Random
Linux 2.6.32 | Per host, incremental (2)
Linux 3.2 | Per host, incremental (1)
Linux 3.8 | Per host, incremental
OpenBSD 4.6 | Random
OpenBSD 5.2 | Random
OS X 10.6.7 | Global, incremental (3)
OS X 10.8.3 | Random
Solaris 11 | Per host, incremental
Windows Server 2003 R2 Standard 64bit, SP2 | Global, incremental
Windows Server 2008 Standard 32bit, SP1 | Global, incremental
Windows Server 2008 R2 Standard 64bit, SP1 | Global, incremental by 2
Windows Server 2012 Standard 64bit | Global, incremental by 2
Windows XP Professional 32bit, SP3 | Global, incremental (4)
Windows Vista Business 64bit, SP1 | Global, incremental
Windows 7 Home Premium 32bit, SP1 | Global, incremental by 2
Windows 7 Ultimate 32bit, SP1 | Global, incremental by 2
Windows 8 Enterprise 32 bit | Global, incremental by 2
*/
#include "libnetutil/npacket.h"
#include "idle_scan.h"
#include "timing.h"
#include "osscan2.h"
#include "nmap.h"
#include "scan_lists.h"
#include "NmapOps.h"
#include "Target.h"
#include "nmap_error.h"
#include "output.h"
#include "tcpip.h"
#include "struct_ip.h"
#include <stdio.h>
extern NmapOps o;
#ifdef WIN32
/* from libdnet's intf-win32.c */
extern "C" int g_has_npcap_loopback;
#endif
struct idle_proxy_info {
Target host; /* contains name, IP, source IP, timing info, etc. */
int seqclass; /* IP ID sequence class (IPID_SEQ_* defined in nmap.h) */
u32 latestid; /* The most recent IP ID we have received from the proxy */
u16 probe_port; /* The port we use for probing IP ID infoz */
u16 max_groupsz; /* We won't test groups larger than this ... */
u16 min_groupsz; /* We won't allow the group size to fall below this
level. Affected by --min-parallelism */
double current_groupsz; /* Current group size being used ... depends on
conditions ... won't be higher than
max_groupsz */
int senddelay; /* Delay between sending pr0be SYN packets to target
(in microseconds) */
int max_senddelay; /* Maximum time we are allowed to wait between
sending probes (when we send a bunch in a row.
In microseconds. */
pcap_t *pd; /* A Pcap descriptor which (starting in
initialize_idleproxy) listens for TCP packets from
the probe_port of the proxy box */
int rawsd; /* Socket descriptor for sending probe packets to the proxy */
struct eth_nfo eth; // For when we want to send probes via raw IP instead.
struct eth_nfo *ethptr; // points to eth if filled out, otherwise NULL
};
/* Finds the IPv6 extension header for fragmentation in an IPv6 packet, and returns
* the identification value of the fragmentation header
*/
int ipv6_get_fragment_id(const struct ip6_hdr *ip6, unsigned int len) {
const unsigned char *p, *end;
u8 hdr;
struct ip6_ext_data_fragment *frag_header = NULL;
if (len < sizeof(*ip6))
return -1;
p = (unsigned char *) ip6;
end = p + len;
hdr = ip6->ip6_nxt;
p += sizeof(*ip6);
/* If the first extension header is not the fragmentation, we search our way
* through the extension headers until we find the fragmentation header */
while (p < end && hdr != IP_PROTO_FRAGMENT) {
if (p + 2 > end)
return -1;
hdr = *p;
p += (*(p + 1) + 1) * 8;
}
if (hdr != IP_PROTO_FRAGMENT || (p + 2 + sizeof(ip6_ext_data_fragment)) > end)
return -1;
frag_header = (struct ip6_ext_data_fragment *)( p + 2 );
return (ntohl(frag_header->ident));
}
/* Sends an IP ID probe to the proxy machine and returns the IP ID.
This function handles retransmissions, and returns -1 if it fails.
Proxy timing is adjusted, but proxy->latestid is NOT ADJUSTED --
you'll have to do that yourself. Probes_sent is set to the number
of probe packets sent during execution */
static int ipid_proxy_probe(struct idle_proxy_info *proxy, int *probes_sent,
int *probes_rcvd) {
struct timeval tv_end;
int tries = 0;
int trynum;
int sent = 0, rcvd = 0;
int maxtries = 3; /* The maximum number of tries before we give up */
struct timeval tv_sent[3], rcvdtime;
int ipid = -1;
int to_usec;
unsigned int bytes;
int base_port;
struct ip *ip;
struct tcp_hdr *tcp = NULL;
static u32 seq_base = 0;
static u32 ack = 0;
static int packet_send_count = 0; /* Total # of probes sent by this program -- to ensure that our sequence # always changes */
u32 packetlen = 0;
u8 *ipv6_packet = NULL;
struct sockaddr_storage ss;
size_t sslen;
struct ip6_hdr *ip6 = NULL;
const void *ipv6_data;
u8 hdr;
int res;
if (o.magic_port_set)
base_port = o.magic_port;
else
base_port = o.magic_port + get_random_u8();
if (seq_base == 0)
seq_base = get_random_u32();
if (!ack)
ack = get_random_u32();
do {
gettimeofday(&tv_sent[tries], NULL);
/* Time to send the pr0be!*/
if (o.af() == AF_INET)
send_tcp_raw(proxy->rawsd, proxy->ethptr,
proxy->host.v4sourceip(), proxy->host.v4hostip(),
o.ttl, false,
o.ipoptions, o.ipoptionslen,
base_port + tries, proxy->probe_port,
seq_base + (packet_send_count++ * 500) + 1, ack, 0, TH_SYN | TH_ACK, 0, 0,
(u8 *) TCP_SYN_PROBE_OPTIONS, TCP_SYN_PROBE_OPTIONS_LEN,
NULL, 0);
else {
ipv6_packet = build_tcp_raw_ipv6(proxy->host.v6sourceip(), proxy->host.v6hostip(),
0x00, 0x0000,
o.ttl,
base_port + tries, proxy->probe_port,
seq_base + (packet_send_count++ * 500) + 1, ack, 0, TH_SYN | TH_ACK, 0, 0,
(u8 *) TCP_SYN_PROBE_OPTIONS, TCP_SYN_PROBE_OPTIONS_LEN,
NULL, 0,
&packetlen);
proxy->host.TargetSockAddr(&ss, &sslen);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send IPv6 packet");
free(ipv6_packet);
}
sent++;
tries++;
/* Now it is time to wait for the response ... */
to_usec = proxy->host.to.timeout;
gettimeofday(&tv_end, NULL);
while ((ipid == -1 || sent > rcvd) && to_usec > 0) {
to_usec = proxy->host.to.timeout - TIMEVAL_SUBTRACT(tv_end, tv_sent[tries - 1]);
if (to_usec < 0)
to_usec = 0; // Final no-block poll
ip = (struct ip *) readip_pcap(proxy->pd, &bytes, to_usec, &rcvdtime, NULL, true);
gettimeofday(&tv_end, NULL);
if (ip) {
if (o.af() == AF_INET) {
if (bytes < (4 * ip->ip_hl) + 14U)
continue;
if (ip->ip_p == IPPROTO_TCP)
tcp = ((struct tcp_hdr *) (((char *) ip) + 4 * ip->ip_hl));
} else if (o.af() == AF_INET6) {
if (ip->ip_v != 6) {
error("IPv6 packet with a version field != 6 received");
} else {
ip6 = (struct ip6_hdr *) ip;
ipv6_data = ipv6_get_data(ip6, &packetlen, &hdr);
if (hdr == IPPROTO_TCP && ipv6_data != NULL) {
tcp = (struct tcp_hdr *) ipv6_data;
}
}
}
if (tcp) {
if (ntohs(tcp->th_dport) < base_port || ntohs(tcp->th_dport) - base_port >= tries || ntohs(tcp->th_sport) != proxy->probe_port || ((tcp->th_flags & TH_RST) == 0)) {
if (ntohs(tcp->th_dport) > o.magic_port && ntohs(tcp->th_dport) < (o.magic_port + 260)) {
if (o.debugging) {
error("Received IP ID zombie probe response which probably came from an earlier prober instance ... increasing rttvar from %d to %d",
proxy->host.to.rttvar, (int) (proxy->host.to.rttvar * 1.2));
}
proxy->host.to.rttvar = (int) (proxy->host.to.rttvar * 1.2);
rcvd++;
} else if (o.debugging > 1) {
char straddr[INET6_ADDRSTRLEN];
if (o.af() == AF_INET)
inet_ntop(AF_INET, &(ip->ip_src), straddr, sizeof(straddr));
else if (o.af() == AF_INET6)
inet_ntop(AF_INET6, &(ip6->ip6_src), straddr, sizeof(straddr));
error("Received unexpected response packet from %s during IP ID zombie probing:", straddr);
readtcppacket((unsigned char *) ip, MIN(ntohs(ip->ip_len), bytes));
}
continue;
}
trynum = ntohs(tcp->th_dport) - base_port;
rcvd++;
if (o.af() == AF_INET)
ipid = ntohs(ip->ip_id);
else if (o.af() == AF_INET6)
ipid = ipv6_get_fragment_id(ip6, bytes);
adjust_timeouts2(&(tv_sent[trynum]), &rcvdtime, &(proxy->host.to));
}
}
}
} while (ipid == -1 && tries < maxtries);
if (probes_sent)
*probes_sent = sent;
if (probes_rcvd)
*probes_rcvd = rcvd;
return ipid;
}
static u16 byteswap_u16(u16 h) {
return ((h&0xff) << 8) | ((h>>8)&0xff);
}
/* Returns the number of increments between an early IP ID and a later
one, assuming the given IP ID Sequencing class. Returns -1 if the
distance cannot be determined */
static int ipid_distance(int seqclass , u32 startid, u32 endid) {
if (seqclass == IPID_SEQ_INCR)
return endid - startid;
if (seqclass == IPID_SEQ_BROKEN_INCR) {
/* Convert to network byte order */
startid = byteswap_u16((u16) startid);
endid = byteswap_u16((u16) endid);
return endid - startid;
}
if (seqclass == IPID_SEQ_INCR_BY_2) {
return (endid - startid)/2;
}
return -1;
}
static void initialize_proxy_struct(struct idle_proxy_info *proxy) {
proxy->seqclass = proxy->latestid = proxy->probe_port = 0;
proxy->max_groupsz = proxy->min_groupsz = 0;
proxy->current_groupsz = 0;
proxy->senddelay = 0;
proxy->max_senddelay = 0;
proxy->pd = NULL;
proxy->rawsd = -1;
proxy->ethptr = NULL;
}
/* Forces the permanent use of the IPv6 extension header for fragmentation in each IPv6 packet sent from
* the idle host to the target or the attacker
* This is achieved by first sending a ping, and afterwards an ICMPv6 Packet Too Big message
* which states that the response from the ping was too big, our MTU is smaller than the IPv6 minimum MTU */
static void ipv6_force_fragmentation(struct idle_proxy_info *proxy, Target *target) {
int hardtimeout = 9000000; /* Generally don't wait more than 9 secs total */
char filter[512]; /* Libpcap filter string */
struct ip *ip;
/* The maximum data size we can create without fragmenting, considering that the headers also need place */
char data[IP6_MTU_MIN - IPv6_HEADER_LEN - ETH_HDR_LEN - ICMPv6_MIN_HEADER_LEN];
unsigned int datalen, bytes;
const unsigned int proxy_reply_timeout = 2000;
const void *rdata; //the data received in the echo response
struct timeval tmptv, rcvdtime, ipv6_packet_send_time;
struct abstract_ip_hdr hdr;
bool response_received = false;
struct icmpv6_hdr *icmp6_header;
u8 *ipv6_packet = NULL;
u32 packetlen = 0;
u16 pingid = 0;
u16 seq = 0;
struct sockaddr_storage ss;
size_t sslen;
int res;
assert(proxy);
/* First, we force the proxy to provide us with a fragmentation header in each packet
by sending an ping and afterwards an ICMPv6 Packet Too Big */
memset(data,'A', sizeof(data));
pingid = get_random_u16();
seq = get_random_u16();
/* pcap, to get the answer. Max size here is the IPv6 minimum MTU */
if ((proxy->pd = my_pcap_open_live(proxy->host.deviceName(), IP6_MTU_MIN, (o.spoofsource) ? 1 : 0, 50)) == NULL)
fatal("%s", PCAP_OPEN_ERRMSG);
Snprintf(filter, sizeof(filter), "icmp6 and src host %s and dst host %s", proxy->host.targetipstr(), proxy->host.sourceipstr());
if (o.debugging)
log_write(LOG_STDOUT, "Packet capture filter (device %s): %s\n", proxy->host.deviceFullName(), filter);
/* Make a ping that is in total 1280 byte long and send it */
proxy->host.TargetSockAddr(&ss, &sslen);
ipv6_packet = build_icmpv6_raw(proxy->host.v6sourceip(), proxy->host.v6hostip(), 0x00, 0x0000, o.ttl, seq , pingid, ICMPV6_ECHO, 0x00, data, sizeof(data) , &packetlen);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send ICMPv6 Echo Request to the idle host");
free(ipv6_packet);
gettimeofday(&ipv6_packet_send_time, NULL);
/* Now let's wait for the answer */
while (!response_received) {
gettimeofday(&tmptv, NULL);
ip = (struct ip *) readip_pcap(proxy->pd, &bytes, proxy_reply_timeout, &rcvdtime, NULL, true);
if (!ip) {
if (TIMEVAL_SUBTRACT(tmptv, ipv6_packet_send_time) >= hardtimeout) {
fatal("Idle scan zombie %s (%s) port %hu cannot be used because it has not returned any of our ICMPv6 Echo Requests -- perhaps it is down or firewalled.",
proxy->host.HostName(), proxy->host.targetipstr(),
proxy->probe_port);
}
continue;
}
datalen = bytes;
rdata = ip_get_data(ip, &datalen, &hdr);
if (hdr.version == 6 && hdr.proto == IPPROTO_ICMPV6) {
icmp6_header = (struct icmpv6_hdr *) rdata;
if (icmp6_header->icmpv6_type == ICMPV6_ECHOREPLY) {
const struct icmpv6_msg_echo *echo;
echo = (struct icmpv6_msg_echo *) ((u8 *) icmp6_header + sizeof(*icmp6_header));
if (ntohs(echo->icmpv6_id) == pingid && ntohs(echo->icmpv6_seq) == seq)
response_received=true;
}
}
}
if (proxy->pd)
pcap_close(proxy->pd);
/* Now we can tell the idle host that its reply was too big, we want it smaller than the IPV6 minimum MTU */
/* the data contains first the MTU we want, and then the received IPv6 package */
*(uint32_t *)&data = ntohl(IP6_MTU_MIN - 2);
memcpy(&data[4], ip, sizeof(data)-4);
ipv6_packet = build_icmpv6_raw(proxy->host.v6sourceip(), proxy->host.v6hostip(), 0x00, 0x0000, o.ttl, 0x00 , 0x00, 0x02, 0x00, data, sizeof(data) , &packetlen);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send spoofed ICMPv6 Echo Request to the idle host");
free(ipv6_packet);
/* Now we do the same in the name of the target */
/* No pcap this time, we won't receive the answer */
memset(data,'A', sizeof(data));
pingid = get_random_u16();
seq = get_random_u16();
ipv6_packet = build_icmpv6_raw(target->v6hostip(), proxy->host.v6hostip(), 0x00, 0x0000, o.ttl, seq , pingid, ICMPV6_ECHO, 0x00, data, sizeof(data) , &packetlen);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send ICMPv6 Echo Request to the idle host");
free(ipv6_packet);
/* Now we guess what answer the decoy host sent to the target, so that we can piggyback this on the ICMPV6 Packet too Big message */
ipv6_packet = build_icmpv6_raw(proxy->host.v6hostip(), target->v6hostip(), 0x00, 0x0000, o.ttl, seq , pingid, ICMPV6_ECHOREPLY, 0x00, data, sizeof(data) , &packetlen);
*(uint32_t *)&data = ntohl(IP6_MTU_MIN - 2);
memcpy(&data[4], ipv6_packet, sizeof(data)-4);
free(ipv6_packet);
ipv6_packet = build_icmpv6_raw(target->v6hostip(), proxy->host.v6hostip(), 0x00, 0x0000, o.ttl, 0x00 , 0x00, 0x02, 0x00, data, sizeof(data) , &packetlen);
/* give the decoy host time to reply to the target */
usleep(10000);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send ICMPv6 PTB to the idle host");
free(ipv6_packet);
}
/* takes a proxy name/IP, resolves it if necessary, tests it for IP ID
suitability, and fills out an idle_proxy_info structure. If the
proxy is determined to be unsuitable, the function whines and exits
the program */
#define NUM_IPID_PROBES 6
static void initialize_idleproxy(struct idle_proxy_info *proxy, char *proxyName,
Target *target, const struct scan_lists *ports) {
unsigned int probes_sent = 0, probes_returned = 0;
int hardtimeout = 9000000; /* Generally don't wait more than 9 secs total */
unsigned int bytes, to_usec;
int timedout = 0;
char *p, *q = NULL, *r;
char *endptr = NULL;
int seq_response_num;
int newipid;
unsigned int i;
char filter[512]; /* Libpcap filter string */
char name[FQDN_LEN + 1];
struct sockaddr_storage ss;
size_t sslen;
u32 sequence_base;
u32 ack = 0;
struct timeval probe_send_times[NUM_IPID_PROBES], tmptv, rcvdtime;
u32 lastipid = 0;
struct ip *ip;
struct tcp_hdr *tcp;
int distance;
u32 ipids[NUM_IPID_PROBES];
u8 probe_returned[NUM_IPID_PROBES];
struct route_nfo rnfo;
assert(proxyName);
u8 *ipv6_packet = NULL;
u32 packetlen = 0;
const struct ip6_hdr *ip6;
u8 ip6hdr;
const void *ip6data;
bool retried_forcing_fragmentation = false;
assert(proxy);
assert(proxyName);
int res;
ack = get_random_u32();
for (i = 0; i < NUM_IPID_PROBES; i++)
probe_returned[i] = 0;
initialize_proxy_struct(proxy);
initialize_timeout_info(&proxy->host.to);
proxy->min_groupsz = o.min_parallelism ? o.min_parallelism : 4;
proxy->max_groupsz = MAX(proxy->min_groupsz, o.max_parallelism ? o.max_parallelism : 100);
proxy->max_senddelay = 100000;
/* If we have an IPv6 address, we specify the port with [address]:port */
if (o.af() == AF_INET)
q = strchr(proxyName, ':');
else if (o.af() == AF_INET6) {
r = strstr(proxyName, "]:");
if (r != NULL)
q = strchr(r, ':');
else
q = NULL;
}
/* If we have a : in IPv4 or [] in IPv6, we strip them off */
if (o.af() == AF_INET && q != NULL ) {
/* I'm lazy, using a size_t we already had around */
sslen = MIN(strcspn(proxyName,":"), sizeof(name) - 1);
strncpy(name, proxyName, sslen);
/* Ensure NULL termination */
name[sslen] = '\0';
}
else if (o.af() == AF_INET6 && strchr(proxyName, '[') != NULL && strchr(proxyName, ']') != NULL) {
sslen = MIN(strcspn(proxyName,"]") - strcspn(proxyName, "[") - 1, sizeof(name) - 1);
strncpy(name, strchr(proxyName, '[') + 1, sslen);
name[sslen] = '\0';
}
else
strncpy(name, proxyName, sizeof(name));
if (q) {
q++;
proxy->probe_port = strtoul(q, &endptr, 10);
if (*q == 0 || !endptr || *endptr != '\0' || !proxy->probe_port) {
fatal("Invalid port number given in IP ID zombie specification: %s", proxyName);
}
} else {
if (ports->syn_ping_count > 0) {
proxy->probe_port = ports->syn_ping_ports[0];
} else if (ports->ack_ping_count > 0) {
proxy->probe_port = ports->ack_ping_ports[0];
} else {
u16 *tmp_ports;
int count;
getpts_simple(DEFAULT_TCP_PROBE_PORT_SPEC, SCAN_TCP_PORT, &tmp_ports, &count);
assert(count > 0);
proxy->probe_port = tmp_ports[0];
free(tmp_ports);
}
}
proxy->host.setHostName(name);
int rc = resolve(name, 0, &ss, &sslen, o.pf());
if (rc != 0) {
fatal("Could not resolve idle scan zombie host \"%s\": %s", name, gai_strerror(rc));
}
proxy->host.setTargetSockAddr(&ss, sslen);
/* Lets figure out the appropriate source address to use when sending
the probes */
proxy->host.TargetSockAddr(&ss, &sslen);
if (!nmap_route_dst(&ss, &rnfo))
fatal("Unable to find appropriate source address and device interface to use when sending packets to %s", proxyName);
if (o.spoofsource) {
o.SourceSockAddr(&ss, &sslen);
proxy->host.setSourceSockAddr(&ss, sslen);
proxy->host.setDeviceNames(o.device, o.device);
} else {
proxy->host.setDeviceNames(rnfo.ii.devname, rnfo.ii.devfullname);
proxy->host.setSourceSockAddr(&rnfo.srcaddr, sizeof(rnfo.srcaddr));
}
if (rnfo.direct_connect) {
proxy->host.setDirectlyConnected(true);
} else {
proxy->host.setDirectlyConnected(false);
proxy->host.setNextHop(&rnfo.nexthop, sizeof(rnfo.nexthop));
}
proxy->host.setIfType(rnfo.ii.device_type);
if (rnfo.ii.device_type == devt_ethernet)
proxy->host.setSrcMACAddress(rnfo.ii.mac);
/* Now lets send some probes to check IP ID algorithm ... */
/* First we need a raw socket ... */
if ((o.sendpref & PACKET_SEND_ETH) && (proxy->host.ifType() == devt_ethernet
#ifdef WIN32
|| (g_has_npcap_loopback && proxy->host.ifType() == devt_loopback)
#endif
)) {
if (!setTargetNextHopMAC(&proxy->host))
fatal("%s: Failed to determine dst MAC address for Idle proxy", __func__);
memcpy(proxy->eth.srcmac, proxy->host.SrcMACAddress(), 6);
memcpy(proxy->eth.dstmac, proxy->host.NextHopMACAddress(), 6);
proxy->eth.ethsd = eth_open_cached(proxy->host.deviceName());
if (proxy->eth.ethsd == NULL)
fatal("%s: Failed to open ethernet device (%s)", __func__, proxy->host.deviceName());
proxy->rawsd = -1;
proxy->ethptr = &proxy->eth;
} else {
#ifdef WIN32
win32_fatal_raw_sockets(proxy->host.deviceName());
#endif
proxy->rawsd = nmap_raw_socket();
if (proxy->rawsd < 0)
pfatal("socket troubles in %s", __func__);
unblock_socket(proxy->rawsd);
proxy->eth.ethsd = NULL;
proxy->ethptr = NULL;
}
if (proxy->host.af() == AF_INET6)
ipv6_force_fragmentation(proxy, target);
/* Now for the pcap opening nonsense ...
Snaplen will be the IPv6 minimum MTU of 1280, because an IPv6 packet
may have any number of extension header up to the minimal IPv6 MTU */
if ((proxy->pd = my_pcap_open_live(proxy->host.deviceName(), IP6_MTU_MIN, (o.spoofsource) ? 1 : 0, 50)) == NULL)
fatal("%s", PCAP_OPEN_ERRMSG);
p = (char *) proxy->host.targetipstr();
q = (char *) proxy->host.sourceipstr();
/* libpcap doesn't find the source port in IPv6 if there is an extension header. So we check for this later in the tcp header. */
Snprintf(filter, sizeof(filter), "tcp and src host %s and dst host %s", p, q);
set_pcap_filter(proxy->host.deviceFullName(), proxy->pd, filter);
if (o.debugging)
log_write(LOG_STDOUT, "Packet capture filter (device %s): %s\n", proxy->host.deviceFullName(), filter);
/* Windows nonsense -- I am not sure why this is needed, but I should
get rid of it at sometime */
sequence_base = get_random_u32();
/* Yahoo! It is finally time to send our probes! */
while (probes_sent < NUM_IPID_PROBES) {
if (o.scan_delay)
enforce_scan_delay(NULL);
else if (probes_sent != 0)
usleep(30000);
/* TH_SYN|TH_ACK is what the proxy will really be receiving from
the target, and is more likely to get through firewalls. But
TH_SYN allows us to get a nonzero ACK back so we can associate
a response with the exact request for timing purposes. So I
think I'll use TH_SYN, although it is a tough call. */
/* We can't use decoys 'cause that would screw up the IP IDs */
if (o.af() == AF_INET)
send_tcp_raw(proxy->rawsd, proxy->ethptr,
proxy->host.v4sourceip(), proxy->host.v4hostip(),
o.ttl, false,
o.ipoptions, o.ipoptionslen,
o.magic_port + probes_sent + 1, proxy->probe_port,
sequence_base + probes_sent + 1, ack, 0, TH_SYN | TH_ACK, 0, 0,
(u8 *) TCP_SYN_PROBE_OPTIONS, TCP_SYN_PROBE_OPTIONS_LEN,
NULL, 0);
else if (o.af() == AF_INET6) {
ipv6_packet = build_tcp_raw_ipv6(proxy->host.v6sourceip(), proxy->host.v6hostip(),
0x00, 0x0000,
o.ttl,
o.magic_port + probes_sent + 1, proxy->probe_port,
sequence_base + probes_sent + 1, ack, 0, TH_SYN | TH_ACK, 0, 0,
(u8 *) TCP_SYN_PROBE_OPTIONS, TCP_SYN_PROBE_OPTIONS_LEN,
NULL, 0,
&packetlen);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send IPv6 packet");
free(ipv6_packet);
}
gettimeofday(&probe_send_times[probes_sent], NULL);
probes_sent++;
/* Time to collect any replies */
while (probes_returned < probes_sent && !timedout) {
to_usec = (probes_sent == NUM_IPID_PROBES) ? hardtimeout : 1000;
ip = (struct ip *) readip_pcap(proxy->pd, &bytes, to_usec, &rcvdtime, NULL, true);
gettimeofday(&tmptv, NULL);
if (!ip) {
if (probes_sent < NUM_IPID_PROBES)
break;
if (TIMEVAL_SUBTRACT(tmptv, probe_send_times[probes_sent - 1]) >= hardtimeout) {
timedout = 1;
}
continue;
} else if (TIMEVAL_SUBTRACT(tmptv, probe_send_times[probes_sent - 1]) >= hardtimeout) {
timedout = 1;
}
if (o.af() == AF_INET) {
if (ip->ip_v != 4) {
error("Received a packet with version field != 4");
continue;
}
if (lastipid != 0 && ip->ip_id == lastipid) {
continue; /* probably a duplicate */
}
lastipid = ip->ip_id;
if (bytes < (4 * ip->ip_hl) + 14U)
continue;
if (ip->ip_p == IPPROTO_TCP) {
tcp = ((struct tcp_hdr *) (((char *) ip) + 4 * ip->ip_hl));
/* Checking now for the source port, which we were not able to do in the libpcap filter */
if (ntohs(tcp->th_sport) != proxy->probe_port) {
continue;
}
if (ntohs(tcp->th_dport) < (o.magic_port + 1) || ntohs(tcp->th_dport) - o.magic_port > NUM_IPID_PROBES || ((tcp->th_flags & TH_RST) == 0)) {
if (o.debugging > 1)
error("Received unexpected response packet from %s during initial IP ID zombie testing", inet_ntoa(ip->ip_src));
continue;
}
seq_response_num = probes_returned;
/* The stuff below only works when we send SYN packets instead of
SYN|ACK, but then are slightly less stealthy and have less chance
of sneaking through the firewall. Plus SYN|ACK is what they will
be receiving back from the target */
probes_returned++;
ipids[seq_response_num] = ntohs(ip->ip_id);
probe_returned[seq_response_num] = 1;
adjust_timeouts2(&probe_send_times[seq_response_num], &rcvdtime, &(proxy->host.to));
}
} else if (o.af() == AF_INET6) {
if (ip->ip_v != 6) {
error("Received a packet with version field != 6");
continue;
} else {
ip6 = (struct ip6_hdr *) ip;
newipid = ipv6_get_fragment_id(ip6, bytes);
if (newipid < 0 ) {
/* ok, the idle host does not seem to append the extension header for fragmentation. Let's try this once more,
* maybe the idle host just adjusted its Path MTU. If we keep on having the problem, we quit */
if (!retried_forcing_fragmentation) {
ipv6_force_fragmentation(proxy, target);
retried_forcing_fragmentation = true;
} else
fatal("IPv6 packet without fragmentation header received - issues with the zombie?");
}
/* now that the additional ipv6 stuff is done, we do as for IPv4 */
if (lastipid != 0 && newipid == (int)lastipid) {
continue; /* probably a duplicate */
}
lastipid = newipid;
ip6data = ipv6_get_data(ip6, &packetlen, &ip6hdr);
if (ip6hdr == IPPROTO_TCP && ip6data != NULL) {
tcp = (struct tcp_hdr *) ip6data;
/* Checking now for the source port, which we were not able to do in the libpcap filter */
if (ntohs(tcp->th_sport) != proxy->probe_port) {
continue;
}
}else
{
error("Malformed packet received");
continue;
}
if (ntohs(tcp->th_dport) < (o.magic_port + 1) || ntohs(tcp->th_dport) - o.magic_port > NUM_IPID_PROBES || ((tcp->th_flags & TH_RST) == 0)) {
if (o.debugging > 1)
error("Received unexpected response packet from %s during initial IP ID zombie testing", inet_ntoa(ip->ip_src));
continue;
}
seq_response_num = probes_returned;
/* The stuff below only works when we send SYN packets instead of
SYN|ACK, but then are slightly less stealthy and have less chance
of sneaking through the firewall. Plus SYN|ACK is what they will
be receiving back from the target */
probes_returned++;
ipids[seq_response_num] = newipid;
probe_returned[seq_response_num] = 1;
adjust_timeouts2(&probe_send_times[seq_response_num], &rcvdtime, &(proxy->host.to));
}
}
}
}
/* Yeah! We're done sending/receiving probes ... now lets ensure all of our responses are adjacent in the array */
for (i = 0, probes_returned = 0; i < NUM_IPID_PROBES; i++) {
if (probe_returned[i]) {
if (i > probes_returned)
ipids[probes_returned] = ipids[i];
probes_returned++;
}
}
if (probes_returned == 0)
fatal("Idle scan zombie %s (%s) port %hu cannot be used because it has not returned any of our probes -- perhaps it is down or firewalled.",
proxy->host.HostName(), proxy->host.targetipstr(),
proxy->probe_port);
if (o.af() == AF_INET)
proxy->seqclass = get_ipid_sequence_16(probes_returned, ipids, 0);
else
proxy->seqclass = get_ipid_sequence_32(probes_returned, ipids, 0);
switch (proxy->seqclass) {
case IPID_SEQ_INCR:
case IPID_SEQ_INCR_BY_2:
case IPID_SEQ_BROKEN_INCR:
log_write(LOG_PLAIN, "Idle scan using zombie %s (%s:%hu); Class: %s\n", proxy->host.HostName(), proxy->host.targetipstr(), proxy->probe_port, ipidclass2ascii(proxy->seqclass));
break;
default:
fatal("Idle scan zombie %s (%s) port %hu cannot be used because IP ID sequence class is: %s. Try another proxy.", proxy->host.HostName(), proxy->host.targetipstr(), proxy->probe_port, ipidclass2ascii(proxy->seqclass));
}
proxy->latestid = ipids[probes_returned - 1];
proxy->current_groupsz = MIN(proxy->max_groupsz, 30);
if (probes_returned < NUM_IPID_PROBES) {
/* Yikes! We're already losing packets ... clamp down a bit ... */
if (o.debugging)
error("Idle scan initial zombie qualification test: %d probes sent, only %d returned", NUM_IPID_PROBES, probes_returned);
proxy->current_groupsz = MIN(12, proxy->max_groupsz);
proxy->current_groupsz = MAX(proxy->current_groupsz, proxy->min_groupsz);
proxy->senddelay += 5000;
}
/* OK, through experimentation I have found that some hosts *cough*
Solaris APPEAR to use simple IP ID incrementing, but in reality they
assign a new IP ID base to each host which connects with them. This
is actually a good idea on several fronts, but it totally
frustrates our efforts (which rely on side-channel IP ID info
leaking to different hosts). The good news is that we can easily
detect the problem by sending some spoofed packets "from" the first
target to the zombie and then probing to verify that the proxy IP ID
changed. This will also catch the case where the Nmap user is
behind an egress filter or other measure that prevents this sort of
sp00fery */
/* this behavior gets quite common in IPv6 so now its even more important to check */
if (target->v4hostip() || target->v6hostip()) {
for (probes_sent = 0; probes_sent < 4; probes_sent++) {
if (probes_sent != 0)
usleep(50000);
if (target->v4hostip()) {
send_tcp_raw(proxy->rawsd, proxy->ethptr,
target->v4hostip(), proxy->host.v4hostip(),
o.ttl, false,
o.ipoptions, o.ipoptionslen,
o.magic_port, proxy->probe_port,
sequence_base + probes_sent + 1, ack, 0, TH_SYN | TH_ACK, 0, 0,
(u8 *) TCP_SYN_PROBE_OPTIONS,
TCP_SYN_PROBE_OPTIONS_LEN, NULL, 0);
} else {
ipv6_packet = build_tcp_raw_ipv6(target->v6hostip(), proxy->host.v6hostip(),
0x00, 0x0000,
o.ttl,
o.magic_port, proxy->probe_port,
sequence_base + probes_sent + 1, ack, 0, TH_SYN | TH_ACK, 0, 0,
(u8 *) TCP_SYN_PROBE_OPTIONS,
TCP_SYN_PROBE_OPTIONS_LEN, NULL, 0,
&packetlen);
res = send_ip_packet(proxy->rawsd, proxy->ethptr, &ss, ipv6_packet, packetlen);
if (res == -1)
fatal("Error occurred while trying to send IPv6 packet ");
free(ipv6_packet);
}
}
/* Sleep a little while to give packets time to reach their destination */
usleep(300000);
newipid = ipid_proxy_probe(proxy, NULL, NULL);
if (newipid == -1)
newipid = ipid_proxy_probe(proxy, NULL, NULL); /* OK, we'll give it one more try */
if (newipid < 0)
fatal("Your IP ID Zombie (%s; %s) is behaving strangely -- suddenly cannot obtain IP ID", proxy->host.HostName(), proxy->host.targetipstr());
distance = ipid_distance(proxy->seqclass, proxy->latestid, newipid);
if (distance <= 0) {
fatal("Your IP ID Zombie (%s; %s) is behaving strangely -- suddenly cannot obtain valid IP ID distance.", proxy->host.HostName(), proxy->host.targetipstr());
} else if (distance == 1) {
fatal("Even though your Zombie (%s; %s) appears to be vulnerable to IP ID sequence prediction (class: %s), our attempts have failed. This generally means that either the Zombie uses a separate IP ID base for each host (like Solaris), or because you cannot spoof IP packets (perhaps your ISP has enabled egress filtering to prevent IP spoofing), or maybe the target network recognizes the packet source as bogus and drops them", proxy->host.HostName(), proxy->host.targetipstr(), ipidclass2ascii(proxy->seqclass));
}
if (o.debugging && distance != 5) {
error("WARNING: IP ID spoofing test sent 4 packets and expected a distance of 5, but instead got %d", distance);
}
proxy->latestid = newipid;
}
}
/* Adjust timing parameters up or down given that an idlescan found a
count of 'testcount' while the 'realcount' is as given. If the
testcount was correct, timing is made more aggressive, while it is
slowed down in the case of an error */
static void adjust_idle_timing(struct idle_proxy_info *proxy,
Target *target, int testcount,
int realcount) {
static int notidlewarning = 0;
if (o.debugging > 1) {
log_write(LOG_STDOUT, "%s: tested/true %d/%d -- old grpsz/delay: %f/%d ",
__func__, testcount, realcount, proxy->current_groupsz, proxy->senddelay);
} else if (o.debugging && testcount != realcount) {
error("%s: testcount: %d realcount: %d -- old grpsz/delay: %f/%d",
__func__, testcount, realcount, proxy->current_groupsz, proxy->senddelay);
}
if (testcount < realcount) {
/* We must have missed a port -- our probe could have been
dropped, the response to proxy could have been dropped, or we
didn't wait long enough before probing the proxy IP ID. The
third case is covered elsewhere in the scan, so we worry most
about the first two. The solution is to decrease our group
size and add a sending delay */
/* packets could be dropped because too many sent at once */
proxy->current_groupsz = MAX(proxy->min_groupsz, proxy->current_groupsz * 0.8);
proxy->senddelay += 10000;
proxy->senddelay = MIN(proxy->max_senddelay, proxy->senddelay);
/* No group size should be greater than .5s of send delays */
proxy->current_groupsz = MAX(proxy->min_groupsz, MIN(proxy->current_groupsz, 500000 / (proxy->senddelay + 1)));
} else if (testcount > realcount) {
/* Perhaps the proxy host is not really idle ... */
/* I guess all I can do is decrease the group size, so that if the proxy is not really idle, at least we may be able to scan cnunks more quickly in between outside packets */
proxy->current_groupsz = MAX(proxy->min_groupsz, proxy->current_groupsz * 0.8);
if (!notidlewarning && o.verbose) {
notidlewarning = 1;
error("WARNING: idle scan has erroneously detected phantom ports -- is the proxy %s (%s) really idle?", proxy->host.HostName(), proxy->host.targetipstr());
}
} else {
/* W00p We got a perfect match. That means we get a slight increase
in allowed group size and we can lightly decrease the senddelay */
proxy->senddelay = (int) (proxy->senddelay * 0.9);
if (proxy->senddelay < 500)
proxy->senddelay = 0;
proxy->current_groupsz = MIN(proxy->current_groupsz * 1.1, 500000 / (proxy->senddelay + 1));
proxy->current_groupsz = MIN(proxy->max_groupsz, proxy->current_groupsz);
}
if (o.debugging > 1)
log_write(LOG_STDOUT, "-> %f/%d\n", proxy->current_groupsz, proxy->senddelay);
}
/* OK, now this is the hardcore idle scan function which actually does
the testing (most of the other cruft in this file is just
coordination, preparation, etc). This function simply uses the
idle scan technique to try and count the number of open ports in the
given port array. The sent_time and rcv_time are filled in with
the times that the probe packet & response were sent/received.
They can be NULL if you don't want to use them. The purpose is for
timing adjustments if the numbers turn out to be accurate */
static int idlescan_countopen2(struct idle_proxy_info *proxy,
Target *target, u16 *ports, int numports,
struct timeval *sent_time, struct timeval *rcv_time) {
int openports;
int tries;
int proxyprobes_sent = 0; /* diff. from tries 'cause sometimes we
skip tries */
int proxyprobes_rcvd = 0; /* To determine if packets were dr0pped */
int sent, rcvd;
int ipid_dist;
struct timeval start, end, latestchange, now;
struct timeval probe_times[4];
int pr0be;
static u32 seq = 0;
int newipid = 0;
int sleeptime;
int lasttry = 0;