/*
* $Id: nemesis-dns.c,v 1.1.1.1 2003/10/31 21:29:36 jnathan Exp $
*
* THE NEMESIS PROJECT
* Copyright (C) 1999, 2000, 2001 Mark Grimes <mark@stateful.net>
* Copyright (C) 2001 - 2003 Jeff Nathan <jeff@snort.org>
*
* nemesis-dns.c (DNS Packet Injector)
*
*/
#include "nemesis-dns.h"
#include "nemesis.h"
#if defined(WIN32)
#include <pcap.h>
#endif
static ETHERhdr etherhdr;
static IPhdr iphdr;
static TCPhdr tcphdr;
static UDPhdr udphdr;
static DNShdr dnshdr;
static FileData pd, ipod, tcpod;
static int got_payload;
static char *payloadfile = NULL; /* payload file name */
static char *ipoptionsfile = NULL; /* TCP options file name */
static char *tcpoptionsfile = NULL; /* IP options file name */
static char *device = NULL; /* Ethernet device */
#if defined(WIN32)
static char *ifacetmp = NULL;
#endif
static void dns_cmdline(int, char **);
static int dns_exit(int);
static void dns_initdata(void);
static void dns_usage(char *);
static void dns_validatedata(void);
static void dns_verbose(void);
void nemesis_dns(int argc, char **argv)
{
const char *module = "DNS Packet Injection";
nemesis_maketitle(title, module, version);
if (argc > 1 && !strncmp(argv[1], "help", 4))
dns_usage(argv[0]);
if (nemesis_seedrand() < 0)
fprintf(stderr, "ERROR: Unable to seed random number generator.\n");
dns_initdata();
dns_cmdline(argc, argv);
dns_validatedata();
dns_verbose();
if (got_payload)
{
if (state)
{
#if defined(WIN32)
if (builddatafromfile(DNSTCP_LINKBUFFSIZE, &pd,
(const char *)payloadfile,
(const u_int32_t)PAYLOADMODE) < 0)
#else
if (builddatafromfile(((got_link == 1) ? DNSTCP_LINKBUFFSIZE :
DNSTCP_RAWBUFFSIZE), &pd, (const char *)payloadfile,
(const u_int32_t)PAYLOADMODE) < 0)
#endif
dns_exit(1);
}
else
{
#if defined(WIN32)
if (builddatafromfile(DNSUDP_LINKBUFFSIZE, &pd,
(const char *)payloadfile,
(const u_int32_t)PAYLOADMODE) < 0)
#else
if (builddatafromfile(((got_link == 1) ? DNSUDP_LINKBUFFSIZE :
DNSUDP_RAWBUFFSIZE), &pd, (const char *)payloadfile,
(const u_int32_t)PAYLOADMODE) < 0)
#endif
dns_exit(1);
}
}
if (got_ipoptions)
{
if (builddatafromfile(OPTIONSBUFFSIZE, &ipod,
(const char *)ipoptionsfile, (const u_int32_t)OPTIONSMODE) < 0)
dns_exit(1);
}
if (state && got_tcpoptions)
{
if (builddatafromfile(OPTIONSBUFFSIZE, &tcpod,
(const char *)tcpoptionsfile, (const u_int32_t)OPTIONSMODE) < 0)
dns_exit(1);
}
if (builddns(ðerhdr, &iphdr, &tcphdr, &udphdr, &dnshdr, &pd, &ipod,
&tcpod, device) < 0)
{
puts("\nDNS Injection Failure");
dns_exit(1);
}
else
{
puts("\nDNS Packet Injected");
dns_exit(0);
}
}
static void dns_initdata(void)
{
/* defaults */
etherhdr.ether_type = ETHERTYPE_IP; /* Ethernet type IP */
memset(etherhdr.ether_shost, 0, 6); /* Ethernet source address */
memset(etherhdr.ether_dhost, 0xff, 6); /* Ethernet destination address */
memset(&iphdr.ip_src.s_addr, 0, 4); /* IP source address */
memset(&iphdr.ip_dst.s_addr, 0, 4); /* IP destination address */
iphdr.ip_tos = IPTOS_LOWDELAY; /* IP type of service */
iphdr.ip_id = (u_int16_t)libnet_get_prand(PRu16); /* IP ID */
iphdr.ip_p = IPPROTO_UDP;
iphdr.ip_off = 0; /* IP fragmentation offset */
iphdr.ip_ttl = 255; /* IP TTL */
tcphdr.th_sport = (u_int16_t)libnet_get_prand(PRu16);
/* TCP source port */
tcphdr.th_dport = 53; /* TCP destination port */
tcphdr.th_seq = (u_int32_t)libnet_get_prand(PRu32);
/* randomize sequence number */
tcphdr.th_ack = (u_int32_t)libnet_get_prand(PRu32);
/* randomize ack number */
tcphdr.th_flags = 0; /* TCP flags */
tcphdr.th_win = 4096; /* TCP window size */
udphdr.uh_sport = (u_int16_t)libnet_get_prand(PRu16);
/* UDP source port */
udphdr.uh_dport = 53; /* UDP destination port */
pd.file_mem = NULL;
pd.file_s = 0;
ipod.file_mem = NULL;
ipod.file_s = 0;
tcpod.file_mem = NULL;
tcpod.file_s = 0;
return;
}
static void dns_validatedata(void)
{
struct sockaddr_in sin;
/* validation tests */
if (iphdr.ip_src.s_addr == 0)
iphdr.ip_src.s_addr = (u_int32_t)libnet_get_prand(PRu32);
if (iphdr.ip_dst.s_addr == 0)
iphdr.ip_dst.s_addr = (u_int32_t)libnet_get_prand(PRu32);
/* if the user has supplied a source hardware addess but not a device
* try to select a device automatically
*/
if (memcmp(etherhdr.ether_shost, zero, 6) && !got_link && !device)
{
if (libnet_select_device(&sin, &device, (char *)&errbuf) < 0)
{
fprintf(stderr, "ERROR: Device not specified and unable to "
"automatically select a device.\n");
dns_exit(1);
}
else
{
#ifdef DEBUG
printf("DEBUG: automatically selected device: "
" %s\n", device);
#endif
got_link = 1;
}
}
/* if a device was specified and the user has not specified a source
* hardware address, try to determine the source address automatically
*/
if (got_link)
{
if ((nemesis_check_link(ðerhdr, device)) < 0)
{
fprintf(stderr, "ERROR: cannot retrieve hardware address of %s.\n",
device);
dns_exit(1);
}
}
/* Attempt to send valid packets if the user hasn't decided to craft an
* anomolous packet
*/
if (state && tcphdr.th_flags == 0)
tcphdr.th_flags |= TH_SYN;
return;
}
static void dns_usage(char *arg)
{
nemesis_printtitle((const char *)title);
printf("DNS usage:\n %s [-v (verbose)] [options]\n\n", arg);
printf("DNS options: \n"
" -i <DNS ID>\n"
" -g <DNS flags>\n"
" -q <# of Questions>\n"
" -W <# of Answer RRs>\n"
" -A <# of Authority RRs>\n"
" -r <# of Additional RRs>\n"
" -P <Payload file>\n"
" -k (Enable TCP transport)\n\n");
printf("TCP options (with -k): \n"
" -x <Source port>\n"
" -y <Destination port>\n"
" -f <TCP flags>\n"
" -fS (SYN), -fA (ACK), -fR (RST), -fP (PSH), -fF (FIN),"
" -fU (URG)\n"
" -fE (ECE), -fC (CWR)\n"
" -w <Window size>\n"
" -s <SEQ number>\n"
" -a <ACK number>\n"
" -u <Urgent pointer offset>\n"
" -o <TCP options file>\n\n");
printf("UDP options (without -k): \n"
" -x <Source port>\n"
" -y <Destination port>\n\n");
printf("IP options: \n"
" -S <Source IP address>\n"
" -D <Destination IP address>\n"
" -I <IP ID>\n"
" -T <IP TTL>\n"
" -t <IP TOS>\n"
" -F <IP fragmentation options>\n"
" -F[D],[M],[R],[offset]\n"
" -O <IP options file>\n\n");
printf("Data Link Options: \n"
#if defined(WIN32)
" -d <Ethernet device number>\n"
#else
" -d <Ethernet device name>\n"
#endif
" -H <Source MAC address>\n"
" -M <Destination MAC address>\n");
#if defined(WIN32)
printf(" -Z (List available network interfaces by number)\n");
#endif
putchar('\n');
dns_exit(1);
}
static void dns_cmdline(int argc, char **argv)
{
int opt, i, flag;
u_int32_t addr_tmp[6];
char *dns_options;
char *p, c;
extern char *optarg;
extern int optind;
#if defined(ENABLE_PCAPOUTPUT)
#if defined(WIN32)
dns_options = "a:A:b:d:D:f:F:g:H:i:I:M:o:O:P:q:r:s:S:t:T:u:w:W:x:y:kvZ?";
#else
dns_options = "a:A:b:d:D:f:F:g:H:i:I:M:o:O:P:q:r:s:S:t:T:u:w:W:x:y:kv?";
#endif
#else
#if defined(WIN32)
dns_options = "a:A:b:d:D:f:F:g:H:i:I:M:o:O:P:q:r:s:S:t:T:u:w:x:y:kvZ?";
#else
dns_options = "a:A:b:d:D:f:F:g:H:i:I:M:o:O:P:q:r:s:S:t:T:u:w:x:y:kv?";
#endif
#endif
while ((opt = getopt(argc, argv, dns_options)) != -1) {
switch (opt)
{
case 'a': /* ACK window */
tcphdr.th_ack = xgetint32(optarg);
break;
case 'A': /* number of authoritative resource records */
dnshdr.num_auth_rr = xgetint16(optarg);
break;
case 'b': /* number of answers */
dnshdr.num_answ_rr = xgetint16(optarg);
break;
case 'd': /* Ethernet device */
#if defined(WIN32)
if (nemesis_getdev(atoi(optarg), &device) < 0)
{
fprintf(stderr, "ERROR: Unable to lookup device: '%d'.\n",
atoi(optarg));
dns_exit(1);
}
#else
if (strlen(optarg) < 256)
{
device = strdup(optarg);
got_link = 1;
}
else
{
fprintf(stderr, "ERROR: device %s > 256 characters.\n",
optarg);
dns_exit(1);
}
#endif
break;
case 'D': /* destination IP address */
if ((nemesis_name_resolve(optarg,
(u_int32_t *)&iphdr.ip_dst.s_addr)) < 0)
{
fprintf(stderr, "ERROR: Invalid destination IP address: "
"\"%s\".\n", optarg);
dns_exit(1);
}
break;
case 'f': /* TCP flags */
p = optarg;
while (*p != '\0')
{
c = *p;
flag = strchr(validtcpflags, c) - validtcpflags;
if (flag < 0 || flag > 7)
{
printf("ERROR: Invalid TCP flag: %c.\n", c);
dns_exit(1);
}
else
{
tcphdr.th_flags |= 1 << flag;
p++;
}
}
break;
case 'F': /* IP fragmentation options */
if (parsefragoptions(&iphdr, optarg) < 0)
dns_exit(1);
break;
case 'g': /* DNS flags */
dnshdr.flags = xgetint16(optarg);
break;
case 'H': /* Ethernet source address */
memset(addr_tmp, 0, sizeof(addr_tmp));
sscanf(optarg, "%02X:%02X:%02X:%02X:%02X:%02X", &addr_tmp[0],
&addr_tmp[1], &addr_tmp[2], &addr_tmp[3], &addr_tmp[4],
&addr_tmp[5]);
for (i = 0; i < 6; i++)
etherhdr.ether_shost[i] = (u_int8_t)addr_tmp[i];
break;
case 'i': /* DNS ID */
dnshdr.id = xgetint16(optarg);
break;
case 'I': /* IP ID */
iphdr.ip_id = xgetint16(optarg);
break;
case 'k': /* use TCP */
iphdr.ip_tos = 0;
iphdr.ip_p = IPPROTO_TCP;
state = 1;
break;
case 'M': /* Ethernet destination address */
memset(addr_tmp, 0, sizeof(addr_tmp));
sscanf(optarg, "%02X:%02X:%02X:%02X:%02X:%02X", &addr_tmp[0],
&addr_tmp[1], &addr_tmp[2], &addr_tmp[3], &addr_tmp[4],
&addr_tmp[5]);
for (i = 0; i < 6; i++)
etherhdr.ether_dhost[i] = (u_int8_t)addr_tmp[i];
break;
case 'o': /* TCP options file */
if (strlen(optarg) < 256)
{
tcpoptionsfile = strdup(optarg);
got_tcpoptions = 1;
}
else
{
fprintf(stderr, "ERROR: TCP options file %s > 256 "
"characters.\n", optarg);
dns_exit(1);
}
break;
case 'O': /* IP options file */
if (strlen(optarg) < 256)
{
ipoptionsfile = strdup(optarg);
got_ipoptions = 1;
}
else
{
fprintf(stderr, "ERROR: IP options file %s > 256 "
"characters.\n", optarg);
dns_exit(1);
}
break;
case 'P': /* payload file */
if (strlen(optarg) < 256)
{
payloadfile = strdup(optarg);
got_payload = 1;
}
else
{
fprintf(stderr, "ERROR: payload file %s > 256 "
"characters.\n", optarg);
dns_exit(1);
}
break;
case 'q': /* number of questions */
dnshdr.num_q = xgetint16(optarg);
break;
case 'r': /* number of additional resource records */
dnshdr.num_addi_rr = xgetint16(optarg);
break;
case 's': /* TCP sequence number */
tcphdr.th_seq = xgetint32(optarg);
break;
case 'S': /* source IP address */
if ((nemesis_name_resolve(optarg,
(u_int32_t *)&iphdr.ip_src.s_addr)) < 0)
{
fprintf(stderr, "ERROR: Invalid source IP address: \"%s\"."
"\n", optarg);
dns_exit(1);
}
break;
case 't': /* IP type of service */
iphdr.ip_tos = xgetint8(optarg);
break;
case 'T': /* IP time to live */
iphdr.ip_ttl = xgetint8(optarg);
break;
case 'u': /* TCP urgent pointer */
tcphdr.th_urp = xgetint16(optarg);
break;
case 'v':
verbose++;
if (verbose == 1)
nemesis_printtitle((const char *)title);
break;
case 'w': /* TCP window size */
tcphdr.th_win = xgetint16(optarg);
break;
case 'x': /* TCP/UDP source port */
tcphdr.th_sport = xgetint16(optarg);
udphdr.uh_sport = xgetint16(optarg);
break;
case 'y': /* TCP/UDP destination port */
tcphdr.th_dport = xgetint16(optarg);
udphdr.uh_dport = xgetint16(optarg);
break;
#if defined(WIN32)
case 'Z':
if ((ifacetmp = pcap_lookupdev(errbuf)) == NULL)
perror(errbuf);
PrintDeviceList(ifacetmp);
dns_exit(1);
#endif
case '?': /* FALLTHROUGH */
default:
dns_usage(argv[0]);
break;
}
}
argc -= optind;
argv += optind;
return;
}
static int dns_exit(int code)
{
if (got_payload)
free(pd.file_mem);
if (got_ipoptions)
free(ipod.file_mem);
if (got_tcpoptions)
free(tcpod.file_mem);
if (device != NULL)
free(device);
if (tcpoptionsfile != NULL)
free(tcpoptionsfile);
if (ipoptionsfile != NULL)
free (ipoptionsfile);
if (payloadfile != NULL);
free(payloadfile);
#if defined(WIN32)
if (ifacetmp != NULL)
free(ifacetmp);
#endif
exit(code);
}
static void dns_verbose(void)
{
if (verbose)
{
if (got_link)
nemesis_printeth(ðerhdr);
nemesis_printip(&iphdr);
if (state)
nemesis_printtcp(&tcphdr);
else
nemesis_printudp(&udphdr);
printf(" [DNS # Questions] %hu\n", dnshdr.num_q);
printf(" [DNS # Answer RRs] %hu\n", dnshdr.num_answ_rr);
printf(" [DNS # Auth RRs] %hu\n", dnshdr.num_auth_rr);
printf(" [DNS # Addtnl RRs] %hu\n\n", dnshdr.num_addi_rr);
}
return;
}
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